TPS2045A TPS2046A TPS2047A TPS2048A TPS2055A TPS2056A TPS2057A TPS2058A - Datasheet Archive

 

TPS2055A, TPS2056A, TPS2057A, TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A ­ SEPTEMBER 2000 ­ REVISED

 

TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 D D D D D D D D D D D 80-m High-Side MOSFET Switch 250 mA Continuous Current Per Channel Independent Thermal and Short-Circuit Protection With Overcurrent Logic Output Operating Range . . . 2.7 V to 5.5 V CMOS- and TTL-Compatible Enable Inputs 2.5-ms Typical Rise Time Undervoltage Lockout 10 µA Maximum Standby Supply Current for Single and Dual (20 µA for Triple and Quad) Bidirectional Switch Ambient Temperature Range, 0°C to 85°C ESD Protection TPS2045A TPS2045A, TPS2055A TPS2055A D PACKAGE (TOP VIEW) GND IN IN EN 1 8 2 7 3 6 4 5 OUT OUT OUT OC TPS2047A TPS2047A, TPS2057A TPS2057A D PACKAGE (TOP VIEW) GNDA IN1 EN1 EN2 GNDB IN2 EN3 NC 1 16 2 15 3 14 4 13 5 12 6 11 7 10 OC1 OUT1 OUT2 OC2 OC3 OUT3 NC NC TPS2046A TPS2046A, TPS2056A TPS2056A D PACKAGE (TOP VIEW) GND IN EN1 EN2 1 8 2 7 3 6 4 5 OC1 OUT1 OUT2 OC2 TPS2048A TPS2048A, TPS2058A TPS2058A D PACKAGE (TOP VIEW) GNDA IN1 EN1 EN2 GNDB IN2 EN3 EN4 1 16 2 15 3 14 4 13 5 12 6 11 7 10 OC1 OUT1 OUT2 OC2 OC3 OUT3 OUT4 OC4 8 9 8 9 The TPS2045A TPS2045A through TPS2048A TPS2048A and TPS2055A TPS2055A through TPS2058A TPS2058A power-distribution All enable inputs are active high for the TPS205xA series. switches are intended for applications where NC ­ No connect heavy capacitive loads and short circuits are likely to be encountered. These devices incorporate 80-m N-channel MOSFET high-side power switches for power-distribution systems that require multiple power switches in a single package. Each switch is controlled by an independent logic enable input. Gate drive is provided by an internal charge pump designed to control the power-switch rise times and fall times to minimize current surges during switching. The charge pump requires no external components and allows operation from supplies as low as 2.7 V. When the output load exceeds the current-limit threshold or a short is present, these devices limit the output current to a safe level by switching into a constant-current mode, pulling the overcurrent (OCx) logic output low. When continuous heavy overloads and short circuits increase the power dissipation in the switch, causing the junction temperature to rise, a thermal protection circuit shuts off the switch to prevent damage. Recovery from a thermal shutdown is automatic once the device has cooled sufficiently. Internal circuitry ensures the switch remains off until valid input voltage is present. These power-distribution switches are designed to current limit at 0.5 A. GENERAL SWITCH CATALOG 33 m, single TPS201xA 0.2 A ­ 2 A TPS202x TPS203x 80 m, single TPS2014 TPS2014 TPS2015 TPS2015 TPS2041 TPS2041 TPS2051 TPS2051 TPS2045 TPS2045 TPS2055 TPS2055 80 m, dual 0.2 A ­ 2 A 0.2 A ­ 2 A 600 mA 1A 500 mA 500 mA 250 mA 250 mA 260 m IN1 OUT IN2 1.3 TPS2042 TPS2042 TPS2052 TPS2052 TPS2046 TPS2046 TPS2056 TPS2056 500 mA 500 mA 250 mA 250 mA TPS2100/1 TPS2100/1 IN1 500 mA IN2 10 mA TPS2102/3/4/5 TPS2102/3/4/5 IN1 500 mA IN2 100 mA 80 m, dual TPS2080 TPS2080 TPS2081 TPS2081 TPS2082 TPS2082 TPS2090 TPS2090 TPS2091 TPS2091 TPS2092 TPS2092 500 mA 500 mA 500 mA 250 mA 250 mA 250 mA 80 m, triple TPS2043 TPS2043 TPS2053 TPS2053 TPS2047 TPS2047 TPS2057 TPS2057 500 mA 500 mA 250 mA 250 mA 80 m, quad TPS2044 TPS2044 TPS2054 TPS2054 TPS2048 TPS2048 TPS2058 TPS2058 500 mA 500 mA 250 mA 250 mA 80 m, quad TPS2085 TPS2085 TPS2086 TPS2086 TPS2087 TPS2087 TPS2095 TPS2095 TPS2096 TPS2096 TPS2097 TPS2097 500 mA 500 mA 500 mA 250 mA 250 mA 250 mA Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 2001, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 1 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 AVAILABLE OPTIONS TA ENABLE RECOMMENDED MAXIMUM CONTINUOUS LOAD CURRENT (A) TYPICAL SHORT-CIRCUIT CURRENT LIMIT AT 25°C (A) PACKAGED DEVICES NUMBER OF SWITCHES Active low Single Active high Active low 0°C to 85°C Active high Active low Dual 0.25 0 25 0.5 05 Triple Active high Active low Active high The D package is available taped and reeled. Add an R suffix to device type (e.g., TPS2045ADR TPS2045ADR) 2 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 Quad SOIC (D) TPS2045AD TPS2045AD TPS2055AD TPS2055AD TPS2046AD TPS2046AD TPS2056AD TPS2056AD TPS2047AD TPS2047AD TPS2057AD TPS2057AD TPS2048AD TPS2048AD TPS2058AD TPS2058AD TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 functional block diagrams TPS2045A TPS2045A Power Switch CS IN OUT Charge Pump EN Current Limit Driver OC UVLO Thermal Sense GND Current sense Active high for TPS205xA series TPS2046A TPS2046A OC1 Thermal Sense GND EN1 Current Limit Driver Charge Pump CS OUT1 UVLO Power Switch CS IN OUT2 Charge Pump Driver Current Limit OC2 EN2 Thermal Sense Current sense Active high for TPS205xA series POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 3 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 functional block diagrams TPS2047A TPS2047A OC1 Thermal Sense GNDA EN1 Current Limit Driver Charge Pump CS OUT1 UVLO Power Switch CS IN1 OUT2 Charge Pump Current Limit Driver OC2 EN2 Thermal Sense Power Switch CS IN2 OUT3 Charge Pump EN3 Driver Current Limit OC3 UVLO Thermal Sense GNDB Current sense Active high for TPS205xA series 4 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 functional block diagrams OC1 TPS2048A TPS2048A Thermal Sense GNDA EN1 Driver Current Limit Charge Pump CS OUT 1 UVLO Power Switch OUT 2 CS IN1 Charge Pump Driver Current Limit OC2 EN2 Thermal Sense OC3 Thermal Sense GNDB EN3 Driver Current Limit Charge Pump CS OUT3 UVLO Power Switch IN2 CS OUT4 Charge Pump Driver Current Limit OC4 EN4 Thermal Sense Current sense Active high for TPS205xA series POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 5 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 Terminal Functions TPS2045A TPS2045A and TPS2055A TPS2055A TERMINAL NAME NO. I/O DESCRIPTION TPS2045A TPS2045A TPS2055A TPS2055A EN 4 ­ I Enable input. Logic low turns on power switch. EN ­ 4 I Enable input. Logic high turns on power switch. GND 1 1 I Ground 2, 3 2, 3 I Input voltage 5 5 O Overcurrent. Open drain output active low 6, 7, 8 6, 7, 8 O Power-switch output IN OC OUT TPS2046A TPS2046A and TPS2056A TPS2056A TERMINAL NAME NO. I/O DESCRIPTION TPS2046A TPS2046A TPS2056A TPS2056A EN1 3 ­ I Enable input. Logic low turns on power switch, IN-OUT1. EN2 4 ­ I Enable input. Logic low turns on power switch, IN-OUT2. EN1 ­ 3 I Enable input. Logic high turns on power switch, IN-OUT1. EN2 ­ 4 I Enable input. Logic high turns on power switch, IN-OUT2. GND 1 1 I Ground IN 2 2 I Input voltage OC1 8 8 O Overcurrent. Open drain output active low, for power switch, IN-OUT1 OC2 5 5 O Overcurrent. Open drain output active low, for power switch, IN-OUT2 OUT1 7 7 O Power-switch output OUT2 6 6 O Power-switch output 6 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 Terminal Functions (Continued) TPS2047A TPS2047A and TPS2057A TPS2057A TERMINAL NAME NO. I/O DESCRIPTION TPS2047A TPS2047A TPS2057A TPS2057A EN1 3 ­ I Enable input, logic low turns on power switch, IN1-OUT1. EN2 4 ­ I Enable input, logic low turns on power switch, IN1-OUT2. EN3 7 ­ I Enable input, logic low turns on power switch, IN2-OUT3. EN1 ­ 3 I Enable input, logic high turns on power switch, IN1-OUT1. EN2 ­ 4 I Enable input, logic high turns on power switch, IN1-OUT2. EN3 ­ 7 I Enable input, logic high turns on power switch, IN2-OUT3. GNDA 1 1 GNDB 5 5 IN1 2 2 I Input voltage I Input voltage Ground for IN1 switch and circuitry. Ground for IN2 switch and circuitry. IN2 6 6 NC 8, 9, 10 8, 9, 10 OC1 16 16 O Overcurrent, open drain output active low, IN1-OUT1 OC2 13 13 O Overcurrent, open drain output active low, IN1-OUT2 OC3 12 12 O Overcurrent, open drain output active low, IN2-OUT3 OUT1 15 15 O Power-switch output, IN1-OUT1 OUT2 14 14 O Power-switch output, IN1-OUT2 OUT3 11 11 O Power-switch output, IN2-OUT3 No connection TPS2048A TPS2048A and TPS2058A TPS2058A TERMINAL NAME I/O NO. DESCRIPTION TPS2048A TPS2048A TPS2058A TPS2058A EN1 3 ­ I Enable input. logic low turns on power switch, IN1-OUT1. EN2 4 ­ I Enable input. Logic low turns on power switch, IN1-OUT2. EN3 7 ­ I Enable input. Logic low turns on power switch, IN2-OUT3. EN4 8 ­ I Enable input. Logic low turns on power switch, IN2-OUT4. EN1 ­ 3 I Enable input. Logic high turns on power switch, IN1-OUT1. EN2 ­ 4 I Enable input. Logic high turns on power switch, IN1-OUT2. EN3 ­ 7 I Enable input. Logic high turns on power switch, IN2-OUT3. EN4 ­ 8 I Enable input. Logic high turns on power switch, IN2-OUT4. GNDA 1 1 Ground for IN1 switch and circuitry. GNDB 5 5 Ground for IN2 switch and circuitry. IN1 2 2 I Input voltage IN2 6 6 I Input voltage OC1 16 16 O Overcurrent. Open drain output active low, IN1-OUT1 OC2 13 13 O Overcurrent. Open drain output active low, IN1-OUT2 OC3 12 12 O Overcurrent. Open drain output active low, IN2-OUT3 OC4 9 9 O Overcurrent. Open drain output active low, IN2-OUT4 OUT1 15 15 O Power-switch output, IN1-OUT1 OUT2 14 14 O Power-switch output, IN1-OUT2 OUT3 11 11 O Power-switch output, IN2-OUT3 OUT4 10 10 O Power-switch output, IN2-OUT4 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 7 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 detailed description power switch The power switch is an N-channel MOSFET with a maximum on-state resistance of 135 m (VI(IN) = 5 V). Configured as a high-side switch, the power switch prevents current flow from OUT to IN and IN to OUT when disabled. The power switch supplies a minimum of 250 mA per switch. charge pump An internal charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of the MOSFET above the source. The charge pump operates from input voltages as low as 2.7 V and requires very little supply current. driver The driver controls the gate voltage of the power switch. To limit large current surges and reduce the associated electromagnetic interference (EMI) produced, the driver incorporates circuitry that controls the rise times and fall times of the output voltage. The rise and fall times are typically in the 2-ms to 4-ms range. enable (ENx, ENx) The logic enable disables the power switch and the bias for the charge pump, driver, and other circuitry to reduce the supply current. The supply current is reduced to less than 10 µA on the single and dual devices (20 µA on the triple and quad devices) when a logic high is present on ENx (TPS204xA) or a logic low is present on ENx (TPS205xA). A logic zero input on ENx or a logic high on ENx restores bias to the drive and control circuits and turns the power on. The enable input is compatible with both TTL and CMOS logic levels. overcurrent (OCx) The OCx open-drain output is asserted (active low) when an overcurrent or overtemperature condition is encountered. The output will remain asserted until the overcurrent or overtemperature condition is removed. current sense A sense FET monitors the current supplied to the load. The sense FET measures current more efficiently than conventional resistance methods. When an overload or short circuit is encountered, the current-sense circuitry sends a control signal to the driver. The driver in turn reduces the gate voltage and drives the power FET into its saturation region, which switches the output into a constant-current mode and holds the current constant while varying the voltage on the load. thermal sense The TPS204xA and TPS205xA implement a dual-threshold thermal trip to allow fully independent operation of the power distribution switches. In an overcurrent or short-circuit condition the junction temperature rises. When the die temperature rises to approximately 140°C, the internal thermal sense circuitry checks to determine which power switch is in an overcurrent condition and turns off that switch, thus isolating the fault without interrupting operation of the adjacent power switch. Hysteresis is built into the thermal sense, and after the device has cooled approximately 20 degrees, the switch turns back on. The switch continues to cycle off and on until the fault is removed. The (OCx) open-drain output is asserted (active low) when overtemperature or overcurrent occurs. undervoltage lockout A voltage sense circuit monitors the input voltage. When the input voltage is below approximately 2 V, a control signal turns off the power switch. Product series designations TPS204x and TPS205x refer to devices presented in this data sheet and not necessarily to other TI devices numbered in this sequence. 8 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 absolute maximum ratings over operating free-air temperature range (unless otherwise noted) Input voltage range, VI(IN) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ­0.3 V to 6 V Output voltage range, VO(OUT) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ­0.3 V to VI(IN) + 0.3 V Input voltage range, VI(ENx) or VI(ENx) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ­0.3 V to 6 V Continuous output current, IO(OUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . internally limited Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table Operating virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 125°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ­65°C to 150°C Lead temperature soldering 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . 260°C Electrostatic discharge (ESD) protection: Human body model MIL-STD-883C MIL-STD-883C . . . . . . . . . . . . . . . . . . . . . 2 kV Machine model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 kV Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTE 1: All voltages are with respect to GND. DISSIPATION RATING TABLE PACKAGE TA 25°C POWER RATING DERATING FACTOR ABOVE TA = 25°C TA = 70°C POWER RATING TA = 85°C POWER RATING D­8 725 mW 5.9 mW/°C 464 mW 377 mW D­16 1123 mW 9 mW/°C 719 mW 584 mW recommended operating conditions MIN MAX 2.7 5.5 V Input voltage, VI(EN) or VI(EN) 0 5.5 V Continuous output current, IO(OUT) (per switch) 0 250 mA Operating virtual junction temperature, TJ 0 125 °C Input voltage, VI(IN) POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 UNIT 9 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 electrical characteristics over recommended operating junction temperature range, VI(IN)= 5.5 V, IO = rated current, VI(EN) = 0 V, VI(EN) = VI(IN) (unless otherwise noted) power switch PARAMETER TEST CONDITIONS TPS204xA MIN TPS205xA TYP MAX MIN TYP MAX VI(IN) = 5 V, IO = 0.25 A tr tf Rise time, output time Fall time, output time 80 100 VI(IN) = 5 V, IO = 0.25 A TJ = 85°C, 90 120 90 120 TJ = 125°C, 100 135 100 135 TJ = 25°C, 90 125 90 125 VI(IN) = 3.3 V, IO = 0.25 A TJ = 85°C, 110 145 110 145 VI(IN) = 3.3 V, IO = 0.25 A Static drain-source on-state resistance, 3.3-V operation 100 VI(IN) = 3.3 V, IO = 0.25 A rDS(on) DS( ) 80 VI(IN) = 5 V, IO = 0.25 A Static drain-source on-state resistance, 5-V operation TJ = 25°C, TJ = 125°C, 120 160 120 160 VI(IN) = 5.5 V, CL = 1 µF, TJ = 25°C, RL=20 2.5 2.5 VI(IN) = 2.7 V, CL = 1 µF, TJ = 25°C, RL=20 3 3 VI(IN) = 5.5 V, CL = 1 µF, VI(IN) = 2.7 V, CL = 1 µF, TJ = 25°C, RL=20 4.4 4.4 TJ = 25°C, RL=20 2.5 UNIT 2.5 m ms ms Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately. enable input ENx or ENx PARAMETER VIH High-level input voltage VIL Low-level Low level input voltage II Input current ton toff TPS204xA Turnon time TPS205xA Turnoff time TEST CONDITIONS 2.7 V VI(IN) 5.5 V TPS204xA MIN TYP TPS205xA MAX 2 MIN TYP MAX 2 UNIT V 4.5 V VI(IN) 5.5 V 0.8 0.8 2.7 V VI(IN) 4.5 V 0.4 0.4 VI(ENx) = 0 V or VI(ENx) = VI(IN) VI(ENx) = VI(IN) or VI(ENx) = 0 V ­0.5 0.5 ­0.5 CL = 100 µF, RL=20 CL = 100 µF, RL=20 0.5 20 20 40 V µA ms 40 current limit PARAMETER IOS Short-circuit output current TEST CONDITIONS VI(IN) = 5 V, OUT connected to GND, Device enabled into short circuit TPS204xA MIN 0.3 TYP 0.5 TPS205xA MAX MIN 0.7 0.3 TYP 0.5 MAX 0.7 UNIT A Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately. 10 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 electrical characteristics over recommended operating junction temperature range, VI(IN)= 5.5 V, IO = rated current, VI(EN) = 0 V, VI(EN) = VI(IN) (unless otherwise noted) (continued) supply current (TPS2045A TPS2045A, TPS2055A TPS2055A) PARAMETER TPS2045A TPS2045A TEST CONDITIONS MIN Leakage current Reverse leakage current VI(EN) = 0 V VI(EN) = VI(IN) Supply current, y , high-level output TJ = 25°C ­40°C TJ 125°C TJ = 25°C ­40°C TJ 125°C OUT connected to ground VI(EN) = VI(IN) ­40°C TJ 125°C VI(EN)= 0 V ­40°C TJ 125°C IN = High g impedance VI(EN) = 0 V VI(EN) = VI(IN) TJ = 25°C MIN TJ = 25°C ­40°C TJ 125°C No Load on OUT No Load on OUT 0.025 MAX TYP MAX 0.025 TJ = 25°C ­40°C TJ 125°C VI(EN) = 0 V Supply current, low-level y , output VI(EN) = VI(IN) TYP TPS2055A TPS2055A 1 UNIT 1 10 µA 10 85 110 100 85 110 µA 100 100 µA 100 0.3 µA 0.3 supply current (TPS2046A TPS2046A, TPS2056A TPS2056A) PARAMETER TPS2046A TPS2046A TEST CONDITIONS MIN Leakage current Reverse leakage current VI(ENx) = 0 V TJ = 25°C ­40°C TJ 125°C VI(ENx) = VI(IN) ­40°C TJ 125°C VI(ENx) = 0 V ­40°C TJ 125°C IN = high g impedance VI(EN) = 0 V VI(EN) = VI(IN) TJ = 25°C No Load on OUT No Load on OUT POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 0.025 MIN TYP MAX 0.025 TJ = 25°C ­40°C TJ 125°C OUT connected to ground TPS2056A TPS2056A MAX TJ = 25°C ­40°C TJ 125°C VI(EN ) = VI(IN) I(ENx) Supply current, y , high-level output TJ = 25°C ­40°C TJ 125°C VI(EN ) = 0 V I(ENx) Supply current, low-level y , output VI(ENx) = VI(IN) TYP 1 UNIT 1 10 µA 10 85 110 100 85 110 µA 100 100 µA 100 0.3 0.3 µA 11 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 electrical characteristics over recommended operating junction temperature range, VI(IN)= 5.5 V, IO = rated current, VI(EN) = 0 V, VI(EN) = VI(IN) (unless otherwise noted) (continued) supply current (TPS2047A TPS2047A, TPS2057A TPS2057A) PARAMETER TPS2047A TPS2047A TEST CONDITIONS MIN VI(ENx) = VI(INx) VI(EN ) = 0 V I(ENx) VI(EN ) = VI(INx) I(IN ) I(ENx) Supply current, y , high-level output MIN TJ = 25°C ­40°C TJ 125°C No load on OUTx Leakage current OUTx connected to ground VI(ENx) = VI(INx) VI(ENx) = 0 V Reverse leakage g current IN = high g impedance VI(ENx) = 0 V VI(ENx) = VI(IN) TYP MAX 0.05 TJ = 25°C ­40°C TJ 125°C No load on OUTx 0.05 MAX TJ = 25°C ­40°C TJ 125°C VI(ENx) = 0 V Supply current, y , low-level output TJ = 25°C ­40°C TJ 125°C TYP TPS2057A TPS2057A 2 UNIT 2 20 µA 20 160 200 200 160 200 µA 200 ­40°C TJ 125°C 200 ­40°C TJ 125°C µA 200 0.3 TJ = 25°C µA 0.3 supply current (TPS2048A TPS2048A, TPS2058A TPS2058A) PARAMETER TPS2048A TPS2048A TEST CONDITIONS MIN Supply current, y , high-level output No Load on OUTx VI(ENx) = 0 V TPS2058A TPS2058A TJ = 25°C ­40°C TJ 125°C MIN TJ = 25°C ­40°C TJ 125°C Leakage current OUTx connected to ground VI(ENx) = VI(INx) VI(ENx) = 0 V Reverse leakage g current IN = high g impedance VI(EN) = 0 V VI(EN) = VI(IN) TYP MAX 0.05 0.05 MAX TJ = 25°C ­40°C TJ 125°C VI(EN ) = VI(INx) I(IN ) I(ENx) No Load on OUTx TJ = 25°C ­40°C TJ 125°C VI(EN ) = 0 V I(ENx) Supply current, y , low-level output VI(ENx) = VI(INx) TYP 2 UNIT 2 20 µA 20 170 220 200 170 220 µA 200 ­40°C TJ 125°C 200 ­40°C TJ 125°C µA 200 0.3 TJ = 25°C µA 0.3 undervoltage lockout PARAMETER TEST CONDITIONS TPS204xA MIN Low-level input voltage Hysteresis TYP MIN 2.5 2 TJ = 25°C TPS205xA MAX 2 100 TYP MAX 2.5 100 UNIT V mV overcurrent OC PARAMETER Sink current Output low voltage Off-state current TEST CONDITIONS VO = 5 V IO = 5 V, MIN VOL(OC) VO = 5 V, TPS204xA VO = 3.3 V POST OFFICE BOX 655303 MAX MIN TYP MAX UNIT 10 Specified by design, not production tested. 12 TYP TPS205xA · DALLAS, TEXAS 75265 10 mA 0.5 0.5 V 1 1 µA TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 PARAMETER MEASUREMENT INFORMATION OUT RL tf tr CL VO(OUT) 90% 90% 10% 10% TEST CIRCUIT 50% VI(EN) 50% toff ton 50% toff ton 90% VO(OUT) 50% VI(EN) 90% VO(OUT) 10% 10% VOLTAGE WAVEFORMS Figure 1. Test Circuit and Voltage Waveforms VI(EN) (5 V/div) VI(EN) (5 V/div) VI(IN) = 5 V TA = 25°C CL = 0.1 µF RL = 20 VO(OUT) (2 V/div) 0 1 2 3 4 5 6 7 8 9 VI(IN) = 5 V TA = 25°C CL = 0.1 µF RL = 20 VO(OUT) (2 V/div) 10 0 2 4 6 8 10 12 14 16 18 20 t ­ Time ­ ms t ­ Time ­ ms Figure 2. Turnon Delay and Rise Time With 0.1-µF Load POST OFFICE BOX 655303 Figure 3. Turnoff Delay and Fall Time With 0.1-µF Load · DALLAS, TEXAS 75265 13 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 PARAMETER MEASUREMENT INFORMATION VI(EN) (5 V/div) VI(EN) (5 V/div) VI(IN) = 5 V TA = 25°C CL = 1 µF RL = 20 VO(OUT) (2 V/div) 0 1 2 3 4 5 6 7 8 VI(IN) = 5 V TA = 25°C CL = 1 µF RL = 20 VO(OUT) (2 V/div) 9 0 10 2 4 6 8 10 12 14 16 18 20 t ­ Time ­ ms t ­ Time ­ ms Figure 4. Turnon Delay and Rise Time With 1-µF Load Figure 5. Turnoff Delay and Fall Time With 1-µF Load VI(IN) = 5 V TA = 25°C RAMP: 1A/10ms VI(ENx) (5 V/div) VO(OUT) (2 V/div) VI(IN) = 5 V TA = 25°C IO(OUTx) (0.2 A/div) 0 1 2 3 4 5 6 7 8 9 IO(OUT) (0.2 A/div) 10 0 10 Figure 6. TPS2055A TPS2055A, Short-Circuit Current, Device Enabled Into Short 14 20 30 40 50 60 70 80 90 100 t ­ Time ­ ms t ­ Time ­ ms POST OFFICE BOX 655303 Figure 7. TPS2055A TPS2055A, Threshold Trip Current With Ramped Load on Enabled Device · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 PARAMETER MEASUREMENT INFORMATION VI(IN) = 5 V TA = 25°C RAMP: 1A/100 ms VI(EN) (5 V/div) VO(OC) (5 V/div) 220 µF 100 µF 47 µF IO(OUT) (0.2 A/div) VI(IN) = 5 V TA = 25°C RL = 20 IO(OUT) (0.2 A/div) 0 20 40 60 80 100 120 140 160 180 200 0 2 4 t ­ Time ­ ms 6 8 10 12 14 16 18 20 t ­ Time ­ ms Figure 9. Inrush Current With 47-µF, 100-µF and 220-µF Load Capacitance Figure 8. OC Response With Ramped Load on Enabled Device VI(IN) = 5 V TA = 25°C VI(IN) = 5 V TA = 25°C VO(OC) (5 V/div) VO(OC) (5 V/div) IO(OUT) (0.5 A/div) IO(OUT) (1 A/div) 0 200 400 600 800 1000 0 200 400 600 800 1000 t ­ Time ­ µs t ­ Time ­ µs Figure 10. 4- Load Connected to Enabled Device POST OFFICE BOX 655303 Figure 11. 1- Load Connected to Enabled Device · DALLAS, TEXAS 75265 15 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 TYPICAL CHARACTERISTICS TURNON DELAY TIME vs INPUT VOLTAGE TURNOFF DELAY TIME vs INPUT VOLTAGE 3.9 10 CL = 1 µF RL = 20 TA = 25°C Turnon Delay Time ­ ms Turnon Delay Time ­ ms 3.6 CL = 1 µF RL = 20 TA = 25°C 3.3 3 8 6 4 2.7 2.4 2.5 3 3.5 4 4.5 5 5.5 2 2.5 6 3 3.5 4 4.5 5 VI ­ Input Voltage ­ V VI ­ Input Voltage ­ V Figure 12 FALL TIME vs INPUT VOLTAGE 2.7 1.9 CL = 1 µF RL = 20 TA = 25°C 1.8 CL = 1 µF RL = 20 TA = 25°C 2.5 f t ­ Fall Time ­ ms r t ­ Rise Time ­ ms 6 Figure 13 RISE TIME vs INPUT VOLTAGE 2.6 5.5 2.4 2.3 1.7 1.6 1.5 2.2 1.4 2.1 2 2.5 3 3.5 4 4.5 5 5.5 6 1.3 2.5 3 VI ­ Input Voltage ­ V Figure 14 16 3.5 4 4.5 5 VI ­ Input Voltage ­ V Figure 15 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 5.5 6 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 TYPICAL CHARACTERISTICS SUPPLY CURRENT, OUTPUT ENABLED vs JUNCTION TEMPERATURE SUPPLY CURRENT, OUTPUT DISABLED vs JUNCTION TEMPERATURE 160 I I(IN) ­ Supply Current, Output Disabled ­ nA I I(IN) ­ Supply Current, Output Enabled ­ µ A 100 90 VI(IN) = 5.5 V VI(IN) = 5 V 80 VI(IN) = 4.5 V 70 VI(IN) = 2.7 V 60 VI(IN) = 3.3 V 50 40 ­40 0 25 85 TJ ­ Junction Temperature ­ °C 140 VI(IN) = 5.5 V 120 VI(IN) = 5 V 100 VI(IN) = 4.5 V 80 VI(IN) = 3.3 V 60 VI(IN) = 2.7 V 40 20 0 ­40 125 0 25 STATIC DRAIN-SOURCE ON-STATE RESISTANCE vs JUNCTION TEMPERATURE 160 VI(IN) = 2.7 V VI(IN) = 3.3 V 120 VI(IN) = 3 V 100 80 VI(IN) = 5 V 60 VI(IN) = 4.5 V 40 20 0 0 25 125 Figure 17 85 INPUT-TO-OUTPUT VOLTAGE vs LOAD CURRENT VI(IN) ­ VO(OUT) ­ Input-to-Output Voltage ­ mV r DS(on) ­ Static Drain-Source On-State Resistance ­ m Figure 16 140 85 TJ ­ Junction Temperature ­ °C 125 70 TA = 25°C VI(IN) = 2.7 V 60 VI(IN) = 4.5 V 50 VI(IN) = 3.3 V 40 VI(IN) = 5 V 30 20 10 0 100 TJ ­ Junction Temperature ­ °C 200 300 400 500 IL ­ Load Current ­ A Figure 18 Figure 19 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 17 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 TYPICAL CHARACTERISTICS SHORT-CIRCUIT OUTPUT CURRENT vs JUNCTION TEMPERATURE THRESHOLD TRIP CURRENT vs INPUT VOLTAGE 0.67 TA = 25°C Load Ramp = 1 A/10 ms 490 VI(IN) = 2.7 V 480 0.65 VI(IN) = 3.3 V Threshold Trip Current ­ A I OS ­ Short-Circuit Output Current ­ mA 500 470 460 VI(IN) = 5 .5V 450 VI(IN) = 4 .5V VI(IN) = 5V 440 430 420 0.63 0.61 0.59 410 400 ­40 0 25 85 TJ ­ Junction Temperature ­ °C 0.57 2.5 125 3 3.5 4 4.5 5 VI ­ Input Voltage ­ V Figure 20 5.5 6 Figure 21 UNDERVOLTAGE LOCKOUT vs JUNCTION TEMPERATURE CURRENT-LIMIT RESPONSE vs PEAK CURRENT 2.36 300 Start Threshold 250 2.32 Current-Limit Response ­µ s UVLO ­ Undervoltage Lockout ­ V 2.34 2.3 2.28 2.26 2.24 Stop Threshold 2.22 2.2 200 150 100 50 2.18 2.16 ­40 0 0 25 85 TJ ­ Junction Temperature ­ °C 125 0 Figure 22 18 2 4 6 Peak Current ­ A Figure 23 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 8 10 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 APPLICATION INFORMATION TPS2045A TPS2045A 2,3 Power Supply 2.7 V to 5.5 V IN 0.1 µF OUT 6,7,8 Load 0.1 µF 5 4 22 µF OC EN GND 1 Figure 24. Typical Application (Example, TPS2045A TPS2045A) power-supply considerations A 0.01-µF to 0.1-µF ceramic bypass capacitor between INx and GND, close to the device, is recommended. Placing a high-value electrolytic capacitor on the output pin(s) is recommended when the output load is heavy. This precaution reduces power-supply transients that may cause ringing on the input. Additionally, bypassing the output with a 0.01-µF to 0.1-µF ceramic capacitor improves the immunity of the device to short-circuit transients. overcurrent A sense FET is employed to check for overcurrent conditions. Unlike current-sense resistors, sense FETs do not increase the series resistance of the current path. When an overcurrent condition is detected, the device maintains a constant output current and reduces the output voltage accordingly. Complete shutdown occurs only if the fault is present long enough to activate thermal limiting. Three possible overload conditions can occur. In the first condition, the output has been shorted before the device is enabled or before VI(IN) has been applied (see Figure 6). The TPS204xA and TPS205xA sense the short and immediately switch into a constant-current output. In the second condition, a short or an overload occurs while the device is enabled. At the instant the overload occurs, very high currents may flow for a short time before the current-limit circuit can react. After the current-limit circuit has tripped (reached the overcurrent trip threshold) the device switches into constant-current mode. In the third condition, the load has been gradually increased beyond the recommended operating current. The current is permitted to rise until the current-limit threshold is reached or until the thermal limit of the device is exceeded (see Figure 7). The TPS204xA and TPS205xA are capable of delivering current up to the current-limit threshold without damaging the device. Once the threshold has been reached, the device switches into its constant-current mode. OC response The OC open-drain output is asserted (active low) when an overcurrent or overtemperature condition is encountered. The output will remain asserted until the overcurrent or overtemperature condition is removed. Connecting a heavy capacitive load to an enabled device can cause momentary false overcurrent reporting from the inrush current flowing through the device, charging the downstream capacitor. The TPS204xA and TPS205xA family of devices are designed to reduce false overcurrent reporting. An internal overcurrent transient filter eliminates the need for external components to remove unwanted pulses. Using low-ESR electrolytic capacitors on the output lowers the inrush current flow through the device during hot-plug events by providing a low-impedance energy source, also reducing erroneous overcurrent reporting. POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 19 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 APPLICATION INFORMATION TPS2045A TPS2045A GND OUT IN OUT IN V+ OUT EN Rpullup OC Figure 25. Typical Circuit for OC Pin (Example, TPS2045A TPS2045A) power dissipation and junction temperature The low on-resistance on the n-channel MOSFET allows small surface-mount packages, such as SOIC, to pass large currents. The thermal resistances of these packages are high compared to those of power packages; it is good design practice to check power dissipation and junction temperature. Begin by determining the rDS(on) of the N-channel MOSFET relative to the input voltage and operating temperature. As an initial estimate, use the highest operating ambient temperature of interest and read rDS(on) from Figure 18. Using this value, the power dissipation per switch can be calculated by: P D + rDS(on) I2 Depending on which device is being used, multiply this number by the number of switches being used. This step will render the total power dissipation from the N-channel MOSFETs. Finally, calculate the junction temperature: T J Where: + PD R qJA ) TA TA = Ambient temperature °C RJA = Thermal resistance SOIC = 172°C/W (for 8 pin), 111°C/W (for 16 pin) PD = Total power dissipation based on number of switches being used. Compare the calculated junction temperature with the initial estimate. If they do not agree within a few degrees, repeat the calculation, using the calculated value as the new estimate. Two or three iterations are generally sufficient to get a reasonable answer. thermal protection Thermal protection prevents damage to the IC when heavy-overload or short-circuit faults are present for extended periods of time. The faults force the TPS204xA and TPS205xA into constant-current mode, which causes the voltage across the high-side switch to increase; under short-circuit conditions, the voltage across the switch is equal to the input voltage. The increased dissipation causes the junction temperature to rise to high levels. The protection circuit senses the junction temperature of the switch and shuts it off. Hysteresis is built into the thermal sense circuit, and after the device has cooled approximately 20 degrees, the switch turns back on. The switch continues to cycle in this manner until the load fault or input power is removed. The TPS204xA and TPS205xA implement a dual thermal trip to allow fully independent operation of the power distribution switches. In an overcurrent or short-circuit condition the junction temperature will rise. Once the die temperature rises to approximately 140°C, the internal thermal sense circuitry checks which power switch is in an overcurrent condition and turns that power switch off, thus isolating the fault without interrupting operation of the adjacent power switch. Should the die temperature exceed the first thermal trip point of 140°C and reach 160°C, both switches turn off. The OC open-drain output is asserted (active low) when overtemperature or overcurrent occurs. 20 POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 APPLICATION INFORMATION undervoltage lockout (UVLO) An undervoltage lockout ensures that the power switch is in the off state at power up. Whenever the input voltage falls below approximately 2 V, the power switch will be quickly turned off. This facilitates the design of hot-insertion systems where it is not possible to turn off the power switch before input power is removed. The UVLO will also keep the switch from being turned on until the power supply has reached at least 2 V, even if the switch is enabled. Upon reinsertion, the power switch will be turned on, with a controlled rise time to reduce EMI and voltage overshoots. universal serial bus (USB) applications The universal serial bus (USB) interface is a 12-Mb/s, or 1.5-Mb/s, multiplexed serial bus designed for low-to-medium bandwidth PC peripherals (e.g., keyboards, printers, scanners, and mice). The four-wire USB interface is conceived for dynamic attach-detach (hot plug-unplug) of peripherals. Two lines are provided for differential data, and two lines are provided for 5-V power distribution. USB data is a 3.3-V level signal, but power is distributed at 5 V to allow for voltage drops in cases where power is distributed through more than one hub across long cables. Each function must provide its own regulated 3.3 V from the 5-V input or its own internal power supply. The USB specification defines the following five classes of devices, each differentiated by power-consumption requirements: D D D D D Hosts/self-powered hubs (SPH) Bus-powered hubs (BPH) Low-power, bus-powered functions High-power, bus-powered functions Self-powered functions Self-powered and bus-powered hubs distribute data and power to downstream functions. The TPS204xA and TPS205xA can provide power-distribution solutions for many of these classes of devices. host/self-powered and bus-powered hubs Hosts and self-powered hubs have a local power supply that powers the embedded functions and the downstream ports. This power supply must provide from 5.25 V to 4.75 V to the board side of the downstream connection under full-load and no-load conditions. Hosts and SPHs are required to have current-limit protection and must report overcurrent conditions to the USB controller. Typical SPHs are desktop PCs, monitors, printers, and stand-alone hubs. Bus-powered hubs obtain all power from upstream ports and often contain an embedded function. The hubs are required to power up with less than one unit load. The BPH usually has one embedded function, and power is always available to the controller of the hub. If the embedded function and hub require more than 100 mA on power up, the power to the embedded function may need to be kept off until enumeration is completed. This can be accomplished by removing power or by shutting off the clock to the embedded function. Power switching the embedded function is not necessary if the aggregate power draw for the function and controller is less than one unit load. The total current drawn by the bus-powered device is the sum of the current to the controller, the embedded function, and the downstream ports, and it is limited to 500 mA from an upstream port. POST OFFICE BOX 655303 · DALLAS, TEXAS 75265 21 TPS2045A TPS2045A, TPS2046A TPS2046A, TPS2047A TPS2047A, TPS2048A TPS2048A TPS2055A TPS2055A, TPS2056A TPS2056A, TPS2057A TPS2057A, TPS2058A TPS2058A CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES SLVS251A SLVS251A ­ SEPTEMBER 2000 ­ REVISED FEBRUARY 2001 APPLICATION INFORMATION low-power bus-powered functions and high-power bus-powered functions Both low-power and high-power bus-powered functions obtain all power from upstream ports; low-power functions always draw less than 100 mA (see Figure 26); high-power functions must draw less than 100 mA at power up and can draw up to 500 mA after enumeration. If the load of the function is more than the parallel combination of 44 and 10 µF at power up, the device must implement inrush current limiting. Power Supply D+ 3.3 V TPS2045A TPS2045A D­ VBUS GND 2,3 10 µF 0.1 µF IN OUT 6, 7, 8 0.1 µF 5 USB Control 4 10 µF Internal Function OC EN GND 1 Figure 26. Low-Power Bus-Powered Function (Example, TPS2045A TPS2045A) USB power-distribution requirements USB can be implemented in several ways, and, regardless of the type of USB device being developed, several power-distribution features must be implemented. D Hosts/self-powered hubs must: ­ ­ D Current-limit downstream ports Report overcurrent conditions on USB VBUS Bus-powered hubs must: ­ ­ Power up at