MIC2596/2597 Dual Channel Negative Voltage Swap Controllers

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MIC2596/2597 Dual Channel Negative Voltage Swap Controllers

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MIC2596/2597
MIC2596/2597
Dual Channel Negative Voltage Swap Controllers
Final Information
General Description
MIC2596 MIC2597 dual channel negative voltage swap controllers designed facilitate safe board insertion into removal from live backplanes. minimize external components, each channel MIC2596/MIC2597 integrated high voltage power MOSFET. Built-in current sensing each channel provides inrush current limiting, regulating channel's output current usersettable maximum. Current sensing also provides programmable overcurrent open-load detection. channel will turned experiences overload no-load conditions lasting longer than programmable intervals. Foldback current limiting holds power dissipation internal MOSFETs safe levels during overloads, very fast shutdown response faults ensures protection both system power supplies load. MIC2596 will automatically attempt restart into overcurrent fault until fault cleared, while MIC2597 will latch output state until reset external action. logic-compatible signal provided each channel indicate overcurrent undercurrent fault conditions.
Features
Allows safe hot-swap -48V systems Operates -70V Programmable inrush current limiting thermally isolated channels Overcurrent fault sensing protection Nuisance trip prevention circuitry Open-load detection Logic compatible Enable Fault signals Separate analog logic ground pins support large system ground differentials (±8V)
Applications
Central Office Switching -48V Power Distribution
Typical Application
VDDA +3.3V FAULT#_CH1 FAULT#_CH2 CONTROLLER ON/OFF_CH1 ON/OFF_CH2
VCLAMP
OUT1 ILIMIT
VOUT1
FAULT#1 FAULT#2 VDDL CTIMER1 CTIMER2 MIC2596
CGATE1
OUT2 CGATE2
VOUT2
ILIMIT2
COL1 COL2
-48V
System-Controlled Swap
Micrel, Inc. 1849 Fortune Drive Jose, 95131 (408) 944-0800 (408) 944-0970 http://www.micrel.com
April 2001
MIC2596/2597
MIC2596/2597
Ordering Information
Part Number MIC2596-1BTS MIC2596-2BTS MIC2597-1BTS MIC2597-2BTS MIC2596-1BTSE MIC2596-2BTSE MIC2597-1BTSE MIC2597-2BTSE Signal Active-High Active-Low Active-High Active-Low Active-High Active-Low Active-High Active-Low Circuit Breaker Function Auto-Retry Auto-Retry Latched Latched Auto-Retry Auto-Retry Latched Latched Package TSSOP TSSOP TSSOP TSSOP Exposed TSSOP Exposed TSSOP Exposed TSSOP Exposed TSSOP
MIC2596/2597
April 2001
MIC2596/2597
Configuration
ILIMIT1 CTIMER1 COL1 VCLAMP VDD/VDDA* COL2 CTIMER2 ILIMIT2 FAULT#1 OUT1 CGATE1 VDDL* CGATE2 OUT2 FAULT#2
20-Pin TSSOP
Descriptions
Number Name FAULT1#/FAULT2# ON1/ON2 Function Fault Status Output, Active-low Asserted when circuit breaker trips upon overcurrent, open-load thermal shutdown conditions. Enable Input Active-high (MIC259x-1) active-low (MIC259x-2). When asserted will initiate start cycle activating GATE output. Toggling will also reset circuit breaker MIC2597. Current Limit Response Timer. capacitor connected this defines period time tFLT which overcurrent event must last signal fault condition turn output off. Negative Supply Voltage Input. Current Limit Set. current limit threshold connecting resistor between this VEE. When current limit threshold channel exceeded tFLT circuit breaker that channel tripped respective output immediately shut off. Switch Outputs. Connect load. Positive Supply Input. Normally connected power ground reference negative supply (-48V) systems. VDDA IC's "analog ground," used internal biasing relative -VEE. FAULT# Clamp Voltage. small bias current into this (usually supplied controlling logic's supply voltage) powers internal circuitry which establishes active voltage FAULT# signals. normal circuit configurations, low-level output voltage will clamped VDDL. Open-Load Detect Timer When load current falls below full scale current limit capacitor connected COL1/COL2 begins change. When voltage across COL1/COL2 rises above 1.32V output immediately shut off. When deasserted when load current above full scale current limit then this held VEE. Tying this will disable this function. Noise filtering capacitors gates main output MOSFETs. Typically range 1000pF 4700pF. VDDL provides ground reference logic-compatible FAULT# signals, while accommodating volts ground differential between controlling logic power ground (VDDA) MIC2596/2597. differential voltage capability required between VDDA VDDL, these pins should tied together part. Connect.
CTIMER1/CTIMER2
ILIMIT1/ILIMIT2
OUT1/OUT2 VDDA
VCLAMP
COL1/COL2
17,14
CGATE1/CGATE2 VDDL
April 2001
MIC2596/2597
MIC2596/2597
Absolute Maximum Ratings
(All voltages referred VEE) (Note Supply Voltage (VDDA VEE) -0.3V Supply Voltage (VDDL VEE) -0.3V VCLAMP (Note -0.3V 5.5V FAULT# pins (Note -0.3V 5.5V Junction Temperature Internally Limited (Human Body Model) [tbd] (Machine Model) [tbd]
Operating Ratings
Supply Voltage (VDDA VEE) Supply Voltage (VDDL VEE) VCLAMP (relative VDDL) 2.5V 5.25V Ambient Temperature -40°C +85°C TSSOP Package: 90°C/W Exposed Package (Note 38°C/W Continuous Junction Temperature 125°C Maximum
Electrical Characteristics
VDDA VDDL 40V, VCLAMP 3.3V, RLIMIT1 RLIMIT2 25°C unless otherwise noted. Symbol UVLO Parameter Supply Current Undervoltage Lockout threshold Undervoltage Lockout hysteresis ICLAMP RDSON IOFF CLAMP supply current FAULT#[1/2] output voltage (Note On-Resistance (Each Switch) On-Resistance (Each Switch) Current Limit Factor (Notes Off-state Output leakage current Off-state Output leakage current ITIMER IOLDTH Overcurrent Timer pull-down current Overcurrent Timer charge current Open Load Detect threshold (percent full-scale output current) (Notes IOLDHYS VTHHI VTHLO Open Load Detect hysteresis (percent full-scale output current) Overload Timer Capacitor high-going threshold voltage Overload Timer -going threshold voltage auto-restart (MIC2596) (Note CGATE Capacitor charge current Open Load Detect Timer high-going threshold voltage Open-Load Detect Timer capacitor charge current Output voltage foldback threshold Upper threshold Lower threshold Foldback output current limit VOUT VFBU, full scale current limit During turn-on 1.12 1.12 0.21 IOUT decreasing IOUT increasing Condition VDDA VDDL 70V, Both outputs -40°C 85°C rising falling FAULT#1 FAULT#2 high VCLAMP 5.25V 250µA 25°C 85°C RLIMIT1 RLIMIT2 Switch off, 25°C VOUT VDDA VDDL Switch off, 85°C VOUT VDDA VDDL 1.32 0.24 1.52 0.27 1700 -0.3 11.5 -0.35 -0.18 2000 2300 -103 12.5 Units
IGATE VCOL ICOL VFBU VFBL IFOLDBACK
1.32 1.52
MIC2596/2597
April 2001
MIC2596/2597
Symbol TPROTECT Parameter threshold Voltage input current High threshold voltage Thermal self-protection points Condition -40°C VCLAMP -40°C 85°C increasing (turn-off) decreasing (turn-on) Parameters tOFF tOFF(UVLO)
Notes: Note Note Note Note Note Note
Units
Turn-on time Turn-off time Rise-time Fall-time Current limit response time Undervoltage OUT1/OUT2 response time
1µF, CGATE 1µF, CGATE 1µF, CGATE 1µF, CGATE CGATE 1µF, CGATE
[tbd] [tbd] [tbd] [tbd] [tbd]
Absolute Maximum Ratings those ratings beyond which part permanently damaged. Functionality guaranteed when part operated Absolute Maximum Ratings. Relative VDDL. exposed package must connected part, electrically isolated. current limit threshold defined current limit factor divided RLIMIT, resistor connected ILIMIT1/ILIMIT2 pins. Open Load Detect guaranteed function programmed maximum output currents <[tbd]mA Final production value TBD.
Timing Diagrams
Device Under Test VOUT VOUT
ON/OFF
tOFF MIC2596-1 MIC2597-1
ON/OFF
tOFF MIC2596-2 MIC2597-2
VOUT
VOUT
April 2001
MIC2596/2597
MIC2596/2597
Functional Diagram
CONTROLLER GROUND
VDDL
VDDA
SYSTEM CONTROLLER 3.3V Supply Control Signals Status Signals
Rpullup1 Rpullup2
MIC2696 MIC2597 VCLAMP ON1/ON2 FAULT#1/FAULT#2 VOUT1 VOUT2
Figure VDDA VDDL Mitigate Ground Noise Effects
Functional Description
Swap Insertion When circuit boards inserted into systems with live power supplies, high inrush currents result charging bulk capacitance that resides across circuit board's supply pins. This inrush current, although transient nature, significant amplitude. Such current spikes cause supply voltages regulation, resulting system crashes. Additionally, high rates di/dt permanent damage electronic components and/or assemblies. MIC2596 family parts designed address these issues limiting inrush current which board other load draw during hot-swap event. addition this inrush current control, MIC2596/MIC2597 provide output current limiting supervisory functions ensure robust protection both host system circuit board. VDDA VDDL some systems, considerable ground differentials occur between physical plant monitor actual power control circuitry. example this would system spanning several racks equipment, with centralized watching over hot-swap functions. order alleviate need optical isolators similar devices when hot-swap parts used such system, MIC2596/MIC2597 have separate grounds their on-chip power-related functions their digital interface pins (ON1, ON2, FAULT1#, FAULT2#). unique architecture these parts allows voltage differentials volts exist between VDDA (the MIC2596/2597 "analog" ground) VDDL (the "logic" ground), without disturbing device performance. distributed systems, VDDA should connected local return power which MIC2596/MIC2597 controlling, while VDDL should separately connected monitor control logic's ground. Figure capability tolerate voltage differentials between VDDA VDDL required, grounds should tied together chip. Start-Up Cycle Referring Typical Applications Circuit, when channel's asserted respective MIC2596/MIC2597 output enabled. minimize inrush current transients output current regulated ensure that does exceed value programmed resistor R1(R2) connected ILIMIT pin. Circuit Breaker Function MIC2596 MIC2597 electronic circuit breakers protect loads, connectors, power supplies, other system components against faults such short circuits. circuit breaker function trips upon overcurrent, open-load thermal shutdown conditions. FAULT# output asserted (taken low) when circuit breaker tripped. timer capacitor (C3) normally pulled small current source. However, whenever current limit threshold exceeded charged much stronger current source. overcurrent condition exists long enough time allow voltage CTIMER cross April 2001
MIC2596/2597
threshold VTHHI circuit beaker tripped output immediately turned off. This time-out period tFLT prevents circuit breaker from erroneously tripping inrush currents during start-up other transient currents caused normal system operation. MIC2596 circuit breaker automatic-reset function. After circuit breaker trips start-up cycle initiated. fault still exists (C3) will again charge VTHHI trip circuit breaker. will then discharged, when voltage across goes below VTHLO another start cycle initiated. This will continue until fault removed channel turned off. MIC2597 circuit breaker only reset either toggling cycling input power. MIC2597 will enabled start only voltage across CTIMER below VTHLO. Foldback Current Limiting During short circuits excessive loads MIC2596 MIC2597 employ foldback current limiting. When differential from VOUT reaches -13V, output current starts fold back. When (VEE VOUT) reaches -31V, output current will limited approximately full scale value. Figure illustrates foldback function.
100%
IOUT (%of ILIM)
VOUT
Figure Foldback Characteristics Fault Status Indication MIC2596 MIC2597 will assert FAULT# output whenever their circuit breaker function activated overcurrent condition. fault will also indicated openload thermal shutdown condition detected. Figure shows FAULT# timing scenarios.
tFLT ILIMIT ILOAD IOLDTH
tFLT
tFLTOL FAULT#
(MIC2597A-1)
Figure MIC2597 Fault Timing
April 2001
MIC2596/2597
MIC2596/2597
example, maximum current from channel MIC2596 0.15A, nominal value RLIMIT that channel would 2000)/0.15A 13.3k. usually necessary, however, allow device tolerances: using 13.3k resistor minimum Data Sheet value Current Limit Factor could restrict part delivering only 127mA. Therefore, necessary RLIMIT find RLIMIT's minimum value: 1700/0.15A 11.3k. This revised value should then tested against other extreme IC's Data Sheet tolerance. 11.3k could program steady-state current high 203mA maximum. system must designed accommodate this maximum current, RLIMIT made adjustable over range necessary maintain precise 150mA current limit (11.3k 15.3k). order minimize error budget issues, tolerance resistor RLIMIT generally recommended. CTIMER capacitor from CTIMER sets length time which overcurrent fault allowed exist channel before channel goes into shutdown. CTIMER normally pulled down small current (1.9µA nominal). During overcurrent condition, pulldown current replaced charging current 72µA nominal. output will disabled once voltage CTIMER becomes 1.32V greater than VEE. Given these numbers, it's easy program time MIC2597 will tolerate output overload before "tripping" shutting output off, using formula CTIMER example, it's desired allow 50msec load capacitance charge before MIC2597 declares "fault," then CTIMER 1.32V) 2.7µF. MIC2596, there slight modification above formula, MIC2596's auto-retry feature. When overcurrent condition occurs, CTIMER will with MIC2597) charge 72µA rate towards 1.32V. Once that threshold reached, output will turned off. However, instead being latched with MIC2597, will turn again when voltage across CTIMER discharged back 0.24V 1.9µA internal pulldown. first fault timeout period following power-on will therefore 72µA), following retry intervals will duration Rearranging, get: CTIMER /1.06V). Again using 50msec example desired fault timeout, this gives CTIMER 3.4µF. this case, 3.3µF would good choice CTIMER. maximum voltage which CTIMER will charge less than 4.7V voltage rating capacitor provides ample safety margin. Note that, MIC2596, ratio CTIMER charge discharge currents always 38:1. This means that overload fault condition, part will attempt restart load with duty cycle approximately 2.5%, which enough protect system, high enough prevent undue restart delays.
Application Information
Thermal Shutdown Power Dissipation Thermal shutdown protection employed protect internal power MOSFETs from damage. Whenever junction temperature channel current limit exceeds 145°C output immediately shut without affecting other channel. channel will automatically turn again when falls below 135°C. junction temperature related internal power dissipation MIC2596 (MIC2597). equation junction temperature [(JA where: junction temperature, total power dissipation part, ambient temperature. determined adding power dissipated each MOSFET power dissipated internal circuitry (PCHIP). equation thus: PCHIP PFET1 PFET2 (VEE IEE) [(I12) RDS(ON)1] [(I22) RDS(ON)2] where continuous output currents channels example, compute maximum continuous output current channel TSSOP package -48V, 70°C, TJ(CONTINUOUS) 125°C: R(J-A) 90°C/W PD(MAX) (125°C 70°C)/(90°C/W) 0.611W 0.611W (-48V -5mA) IMAX2 2.5) 0.371W IMAX2 0.371W/(2 2.5) IMAX2 0.0742 IMAX 272mA channel Similarly, package, 85°C TJ(CONTINUOUS) 125°C: R(J-A) 38°C/W PD(MAX) (125°C 85°C)/(38°C/W) 1.05W 1.05 (-48V -5mA) IMAX2 2.5) 0.81W IMAX2 0.81W/(2 2.5) IMAX2 0.162 IMAX 402mA channel Note that each case assumption been made that load currents will same both channels. External Components small number passive components used each channel MIC2596/MIC2597 program such values maximum output current short circuit "trip" interval. Calculating values these parts straightforward exercise, once nomenclature effect each such part understood. This section addresses each programmable showing sample calculation that pin. RLIMIT resistor from ILIMIT sets maximum operating current channel. formula calculating this resistance RLIMIT(NOMINAL) MIC2596/2597
April 2001
MIC2596/2597
special functions MIC2596 family parts ability detect only overload faults, also undercurrent (open-load) faults. time which channel's output must load below minimum current level (which preset percentage ILIMIT Data Sheet Electrical Tables) COL. When undercurrent condition detected, charged from relative towards threshold voltage 1.32V above current 17µA (nominal). This gives formula example, no-load detection period 75msec desired, found 0.97µF. closest standard value. Once output current goes above minimum load current, discharged VEE. maximum voltage which will charge less than 4.7V voltage rating capacitor provides ample safety margin. important note that neither MIC2596 MIC2597 will attempt "auto-retry" upon detecting openload condition. either these parts shuts both
output following such condition, affected output(s) only turned again turning channel(s) then back cycling power open load detection capability needed given channel, defeated tying that channel VEE. CGATE This direct connection gate each channel's internal power MOSFET. Typically, used connect capacitor range 1000pF 4700pF between MOSFET gate VEE, augment noise immunity channel. This especially helps with regard dv/dt appearing channel's output, which could otherwise couple through drain-gate capacitance MOSFET's input. internal MOSFET N-channel device negative channel's power path, negative terminal CGATE should connect VEE, positive terminal IC's CGATE pin. voltage rating well suited approximately which will appear CGATE when internal MOSFET fully enhanced.
VDDA
VCLAMP
OUT1 ILIMIT
VOUT1
FAULT#1 FAULT#2 VDDL CTIMER1 CTIMER2 MIC2596-2
CGATE1
OUT2 CGATE2
VOUT2
ILIMIT2
COL1 COL2
-48V
Stand Alone Swap Application
April 2001
MIC2596/2597
MIC2596/2597
Package Information
5.40 (0.213) 5.20 (0.205) 7.90 (0.311) 7.65 (0.301)
DIMENSIONS: (INCH)
0.875 (0.034) 7.33 (0.289) 7.07 (0.278) 2.00 (0.079) 1.73 (0.068)
0.22 (0.009) 0.13 (0.005)
0.38 (0.015) 0.25 (0.010)
0.21 (0.008) 0.05 (0.002) 0.65 (0.0260) COPLANARITY: 0.10 (0.004)
1.25 (0.049) 0.95 (0.037) 0.55 (0.022)
20-Pin TSSOP (TS)
5.40 (0.213) 5.20 (0.205) 7.90 (0.311) 7.65 (0.301)
DIMENSIONS: (INCH)
0.875 (0.034) 7.33 (0.289) 7.07 (0.278) 2.00 (0.079) 1.73 (0.068)
0.22 (0.009) 0.13 (0.005)
0.38 (0.015) 0.25 (0.010)
0.21 (0.008) 0.05 (0.002) 0.65 (0.0260) COPLANARITY: 0.10 (0.004)
1.25 (0.049) 0.95 (0.037) 0.55 (0.022)
Exposed Bottom View
20-Pin Exposed TSSOP (TSE)
MIC2596/2597
April 2001
MIC2596/2597
April 2001
MIC2596/2597
MIC2596/2597
MICREL INC. 1849 FORTUNE DRIVE JOSE, 95131
(408) 944-0800 (408) 944-0970 http://www.micrel.com
This information believed accurate reliable, however responsibility assumed Micrel infringement patents other rights third parties resulting from use. license granted implication otherwise under patent patent right Micrel Inc. 2001 Micrel Incorporated
MIC2596/2597
April 2001

MIC2596/2597 Dual Channel Negative Voltage Swap Controllers

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