TC18C46 TC18C46 TC28C46 TC28C46 TC38C46 TC38C46 CMOS CURRENT MODE

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TC18C46 TC18C46 TC28C46 TC28C46 TC38C46 TC38C46 CMOS CURRENT MODE

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CMOS CURRENT MODE CONTROLLERS
TC18C46 TC18C46 TC28C46 TC28C46 TC38C46 TC38C46
CMOS CURRENT MODE CONTROLLER
Isolated Output Drive Power CMOS Construction Supply Current Typ. Wide Supply Voltage Operation Latch-Up Immunity 500mA Outputs Above Below Rail Input Protection High Output Drive 500mA Peak Current Mode Control Fast Rise/Fall Time 50nsec 1000pF High Frequency Operation 500kHz Hysteresis Guaranteed Programmable Current Limit Shutdown Available Double Ended Soft Start Prop Delay Current Output 350nsec Typ. Prop Delay Shutdown Output 400nsec Typ. TC38C46 Compatible with Unitrode UC3846 Protected ±2kV
GENERAL DESCRIPTION
TC38C46 current mode CMOS control draws only supply current, driven without costly 50-60 transformer. output drive stage capable high drive currents, 300mA typical. TC38C46 compatible with earlier bipolar products that designers easily update older designs. number improvements have been added. This second generation part been designed with isolated drive stage. Unlike cousin, TC170, output stage TC38C46 from separate power supply such secondary winding output transformer. This allows bootstrap start-up power supply.
ORDERING INFORMATION
Part TC18C46MJE TC28C46EOE TC28C46EPE TC38C46COE TC38C46CPE Configuration Non-Inverting Non-Inverting Non-Inverting Non-Inverting Non-Inverting Pkg./Temperature 16-Pin CerDIP 55°C +125°C 16-Pin SOIC (Wide) +85°C 16-Pin Plastic (Narrow) 40°C +85°C 16-Pin SOIC (Wide) +70°C 16-Pin Plastic (Narrow) +70°C
FUNCTIONAL BLOCK DIAGRAM
VREF SYNC CURRENT SENSE INPUT CURRENT SENSE INPUT COMPENSATION ERROR INPUT ERROR INPUT ERROR AMPLIFIER 100µA LIMIT BUFFER AMPLIFIER 350mV LOCK-UP AMPLIFIER TC18C46 TC28C46 TC38C46 3.5k POSITIVE FEEDBACK SHUTDOWN COMPARATOR 350mV CURRENT SENSE AMPLIFIER COMPARATOR .65V LATCH OSCILLATOR UNDER VOLTAGE LOCKOUT VOLT REFERENCE
OUTPUT
OUTPUT GROUND
CURRENT LIMIT SOFT START ADJUST SHUTDOWN
TC38C46 OUTPUTS STATE
TC18/28/28/C46-8 9/23/96
TelCom Semiconductor reserves right make changes circuitry specifications devices.
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
ABSOLUTE MAXIMUM RATINGS*
Output Current, Source Sink (Pins .500mA Analog Inputs (Pins 0.3V +VIN Reference Output Current (Pin Sync Output Current (Pin Error Amplifier Output Current (Pin Soft Start Sink Current (Pin 50mA Oscillator Charging Current (Pin .5mA Supply Voltage .18V Maximum Chip Temperature 150°C Storage Temperature 65°C +150°C Lead Temperature (Soldering, sec) 300°C Package Thermal Resistance CerDIP RJ-A 150°C/W CerDIP RJ-C 55°C/W PDIP RJ-A 125°C/W PDIP RJ-C 45°C/W SOIC RJ-A 250°C/W SOIC RJ-C 75°C/W
*NOTES: voltages with respect Ground, Currents positive into, negative specified terminal. 2.Static-sensitive device. Unused devices must stored conductive material. Protect devices from static discharge static fields. Stresses above those listed under Absolute Maximum Ratings cause permanent damage device. These stress ratings only functional operation device these other conditions above those indicated operational sections specifications implied. Exposure Absolute Maximum Rating Conditions extended periods affect device reliability.
CONFIGURATIONS 16-Pin Plastic (Narrow) 16-Pin CerDIP
CURRENT LIMIT/ SOFT START VREF CURRENT SENSE CURRENT SENSE ERROR ERROR COMP TC18C46MJE TC28C46EPE TC38C46CPE SHDN OUTPUT OUTPUT SYNC CURRENT LIMIT/ SOFT START VREF CURRENT SENSE CURRENT SENSE ERROR ERROR COMP
16-Pin SOIC (Wide)
TC28C46EOE TC38C46COE
SHDN OUTPUT OUTPUT SYNC
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
ELECTRICAL CHARACTERISTICS: unless otherwise stated, these specifications apply 55°C +125°C TC18C46; 40°C +85°C TC28C46; +70°C TC38C46; 16V; 30.1k; 270pF.
TC18C46 TC28C46 Parameter Reference Section
Output Voltage Line Regulation Load Regulation Temp Coefficient Total Output Range Long Term Drift Short Circuit Output Current Output Noise Voltage 25°C, 10mA Over Operating Range, (Note Line, Load, Temperature (Note 125°C, 1000 (Note VREF kHz, 25°C (Note 25°C Over Operating Range (Note 4.97 96.5 -0.5 4.75 5.24 106.5 0.06 ±100 ±100 4.94 96.5 -0.5 4.75 ±0.1 ±0.1 5.26 106.5 0.06 ±0.5 ±0.5 mV/°C µV(rms) %/°C V/µsec
TC38C46 Units
Test Conditions
Oscillator Section
Initial Accuracy Voltage Coefficient Temp Coefficient Clock Ramp Reset Current Ramp Amplitude Sync Output High Level Sync Output Level Sync Input High Level Sync Input Level Sync Input Current
(Note (Note (Note (Note Sync Voltage 5.25V,
Error Section
Input Offset Voltage Input Bias Current Input Offset Current Open Loop Voltage Gain Gain Bandwidth Product CMRR PSRR Output Sink Current Output Source Current High Level Output Volt Level Output Volt Slew Rate
100k 25°C (Note V(EA V(EA+) 4.9V, V(CMPTR) 1.2V V(EA V(EA+) 5.1V, V(CMPTR) 2.5V (CMPTR) GND, (CMPTR) GND,
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
ELECTRICAL CHARACTERISTICS (Cont): Unless otherwise stated, these specifications apply
-55°C +125°C TC18C46; 40°C +85°C TC28C46; +70°C TC38C46; 16V; 30.1k; 270pF. TC18C46 TC28C46 Parameter Current Sense Section
Amplifier Gain Differential Input Signal (VPin 4-VPin Input Offset Voltage CMRR PSRR Input Bias Current Input Offset Current Input Common Mode Range Delay Outputs (Notes (Note (Note 12V, (Note 16V, (Note (Note (Note (Note 25°C, (Note (Shutdown Unlatched) 0.65 ±0.1 0.85 ±100 0.65 ±0.1 0.85 ±100 nsec nsec nsec nsec nsec
TC38C46 Units
Test Conditions
Current Limit Adjust Section
Current Limit Voltage Offset Input Impedance
Shutdown Terminal Section
Threshold Voltage Input Voltage Range Latching Current (IPin Non-Latching Current (IPin1) Pulse Width Delay Outputs (Note (Note (Note (Note (Note
Output Section
Output Level (ON) Output High Level (ON) Output Rise Time Output Fall Time ISINK 20mA ISOURCE 20mA
Undervoltage Lockout Section
Undervoltage Threshold Start Threshold Threshold Hysteresis
Total Standby Current
Supply Current Start-Up Current
NOTES: These parameters, although guaranteed over recommended operating conditions, tested production. Parameter measured trip point latch with VPin VREF, VPin Amplifier gain defined
VPIN VPIN VPIN Current into guaranteed latch circuit shutdown state. Current into guaranteed latch circuit shutdown state.
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
Peak Current Limit Setup
Resistors CURRENT LIMIT input (pin peak current limit (Figure potential easily calculated: VREF input pulse should least 100nsec wide have amplitude least order minimum propagation delay from input output. these parameters met, delay should less than 400nsec 25°C; however, delay time will increase device temperature rises.
Soft Restart From Shutdown
soft restart programmed nonlatched shutdown operation used. capacitor will cause gradual increase potential toward When voltage reaches 0.75V, latch input removed circuit establishes regulated output voltage. soft-start operation forces output drivers initially operate with minimum duty cycle peak currents. Even soft start required, necessary insert capacitor between ground current greater than 140µA. This capacitor will prevent "noise triggering" latch, minimize soft-start effect.
should selected first. shutdown circuit feature latched (VREF 0.35)/R1 <65µA latched currents greater than 140µA. error amplifier output voltage clamped from going above through limit buffer amplifier. Peak current sensed amplified current amplifier which fixed gain IPCL, peak current limit, current that causes comparator noninverting input exceed potential inverting input. Once comparator trip point exceeded, both outputs disabled. IPCL easily calculated: IPCL where: VREF 0.65V (RS)
Soft-Start Power-Up
During power-up, capacitor initiates softstart cycle. input voltage (pin exceeds undervoltage lockout potential (7V), turned OFF, ending undervoltage lockout. Whenever comparator inverting input below 0.65V, both outputs disabled. When undervoltage lockout start threshold exceeded, capacitor begins charge. duty cycle increases until operating output voltage reached. Soft-start operation forces output drivers initially operate with minimum duty cycle peak current.
VREF Internal voltage reference 5.1V Gain current-sense amplifier 0.65V Current limit offset Both driver OUTPUTS (pins (LOW) when peak current limit exceeded. When sensed current goes below IPCL, circuit operates normally.
Current-Sense Amplifier
current-sense amplifier operates fixed gain Maximum differential input voltage (VPIN4 -VPIN3) 1.1V. Common-mode input voltage range Resistive-sensing methods shown Figure Figure 2(A), simple filter limits transient voltage spikes caused external output transistor-collector capacitance. Transformer coupling (Figure offers isolation better power efficiency, cost complexity increase. order minimize propagation delay from input current amplifier output terminals, current ramp should order 1µsec width (min). Typical time delay values 225nsec region 25°C. delay time increases with device temperature that 50°C, delay times increased much 100nsec.
Output Shutdown
outputs turned quickly through SHUTDOWN input (pin 16). signal greater than 360mV forces shutdown comparator output HIGH. latch held set, disabling outputs. also turned VREF/R1 greater than 140µA, positive feedback through amplifier keeps inverting comparator inverting input below 0.65V. remains even after shutdown input signal removed. This because lockup amplifier latched mode driving This state cleared only through power-up cycle. Outputs will disabled whenever potential below 0.65V. shutdown terminal gives fast, direct disable controller output transistors. System protection remote shutdown applications possible.
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
SWITCH CURRENT CURRENT-SENSE AMPLIFIER 100µA ERROR AMPLIFIER LIMIT BUFFER AMPLIFIER 350mV TC18C46 TC28C46 TC38C46 POSITIVE FEEDBACK SHUTDOWN COMPARATOR 350mV 3.5k COMPARATOR FROM UNDERVOLTAGE LOCKOUT LATCH VREF 5.1V
OUTPUT (LOW)
0.65V
LOCK-UP AMPLIFIER
Figure Maximum Peak Output Current
CURRENTSENSE AMPLIFIER
VOUT
CURRENTSENSE AMPLIFIER
*OPTIONAL FILTER
TCx8C46
TCx8C46
Ground Reference
Above-Ground Resistive Sensing
Figure Resistive Sensing
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
3.15 CURRENT- SENSE AMPLIFIER TCX8C46
TCx8C46
MASTER
SYNC
CMPTR
TC4427
Figure Transformer Isolated Current Sense
Under Voltage Lockout
under voltage lockout circuit forces controller outputs (LOW) supply voltage below Threshold hysteresis 0.8V guarantees clean, jitterfree turn-ON turn-OFF points. hysteresis also reduces capacitive filtering requirements controller supply input (pin 15).
VREF SYNC CMPTR
TCx8C46
Circuit Synchronization
Current-mode-controlled power supplies operated parallel with common load. Paralleled converters will equally share load current. Voltage-mode controllers unequally share load current, decreasing system reliability. more these controllers slaved together parallel operation. Circuits operate from master controller internal oscillator with external driver (Figure Devices also slaved external oscillator (Figure Disable internal slave device oscillators grounding Slave controllers derive oscillator from bidirectional synchronization output signal bidirectional that intended both sync output input. This accomplished making output driver "weak." This advantageous that eliminates additional from package does enable device directly drive another device. order make effective driver, buffer required (Figure order sync input, necessary overcome internal driver. This requires pulse with amplitude equal Since must above undervoltage lockout disabled, CMOS opencollector driver should used.
SLAVE
Figure Master/Slave Parallel Operation
EXTERNAL* OSCILLATOR TC4427 TCx8C46 SYNC VREF *PULSE WIDTH OSCILLATOR SYNC TCx8C46 VREF
Figure External Clock Synchronization
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
1/FO
0.5V 3.5V
ICHARGE
3.5V
3.5V
TCHG
SYNC DISCHARGE CURRENT
OUTPUT DEAD TIME (TD)
Figure Oscillator Circuit
Selection Timing Capacitor Resistor
First determine frequency operation desired dead" time", (see Fig.6 graph). need choose Substituting rearranging, (.002 3.5)
Knowing choosing permits calculation current mirror Fig. shows: ICHG ICHG Also,
Where,
Volts TCHG
During discharge (TD), discharge current pulls minus ICHG that keeps trying charge ICHG ,where Volts
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
TYPICAL CHARACTERISTICS
18C46 Dead Time
11000 10000 Dead Time (nsec) 8000 7000 6000 5000 4000 3000 2000 1000 1000 2000 3000 4000 5000 100k Dead Time (nsec) 9000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 1000pF 500pF 100pF 2200pF 4700pF
18C46 Dead Time
18C46 Frequency
FOSC, FOSC, 1000 2000 3000 4000 5000 100k
18C46 Frequency
100pF
500pF 1000pF 2200pF 4700pF
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
DESCRIPTION
Symbol
Description
setting peak current limit threshold sense inputs second function this Soft-Start programming with capacitor between this ground, output reference supply voltage volts. This reference supply minimum 20mA output current. current sense inverting input sensing peak current pass transistor through series current monitor resistor. non-inverting input sensing peak current pass transistor. positive current sense resistor connected here. non-inverting input sensing voltage feedback from output voltage regulation. compensating feedback loop response. input timing capacitor, oscillator frequency conjunction with resistor input. second function setting crossover dead time outputs, pins input timing resistor, oscillator frequency setting (constant) current charge rate capacitor input output oscillator synchronization pulse. output drive phase drive push pull transistor ground return path input output signals. supply power input terminal output drivers. output drive phase drive push pull transistor voltage bias supply input circuits except output drivers input shutdown when 350mV threshold exceeded: both output drives will then terminated.
CURRENT LIMIT, SOFT START
VREF CURRENT SENSE CURRENT SENSE ERROR ERROR COMP
SYNC OUTA OUTB SHUT
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
PACKAGE DIMENSIONS
16-Pin CerDIP
.300 (7.62) .245 (6.22)
.080 (2.03) MAX.
.030 (0.76) MIN.
.780 (19.81) .740 (18.80) .200 (5.08) .160 (4.06) .200 (5.08) .125 (3.18) .040 (1.02) .020 (0.51) .015 (0.38) .008 (0.20)
.320 (8.13) .290 (7.37)
.150 (3.81) MIN.
MIN.
.110 (2.79) .090 (2.29)
.065 (1.65) .045 (1.14)
.400 (10.16) .320 (8.13) .020 (2.51) .016 (0.41)
16-Pin Plastic (Narrow)
.260 (6.60) .240 (6.10)
.770 (19.56) .745 (18.92) .200 (5.08) .140 (3.56) .150 (3.81) .115 (2.92)
.310 (.787) .290 (.737)
.040 (1.02) .020 (0.51)
.015 (0.38) .008 (0.20) .400 (10.16) .310 (7.87)
MIN.
.110 (2.79) .090 (2.29)
.070 (1.78) .045 (1.14)
.022 (0.56) .015 (0.38)
Dimensions: inches (mm)
CMOS CURRENT MODE CONTROLLERS TC18C46 TC28C46 TC38C46
PACKAGE DIMENSIONS (Cont.) 16-Pin SOIC (Wide)
.299 (7.59) .419 (10.65) .290 (7.40) .394 (10.10)
.413 (10.49) .398 (10.10) .104 (2.64) .097 (2.46) .050 (1.27) TYP. .019 (0.48) .014 (0.36) .012 (0.30) .004 (0.10)
MAX. .050 (1.27) .015 (0.40)
.013 (0.33) .009 (0.23)
Dimensions: inches (mm)
Sales Offices
TelCom Semiconductor 1300 Terra Bella Avenue P.O. 7267 Mountain View, 94039-7267 TEL: 650-968-9241 FAX: 650-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TelCom Semiconductor Austin Product Center 9101 Burnet Suite Austin, 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom Semiconductor H.K. Ltd. Chuk Street, Ground Floor Kong, Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957
Printed U.S.A.

TC18C46 TC18C46 TC28C46 TC28C46 TC38C46 TC38C46 CMOS CURRENT MODE

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