LTC2924

LTC2924 Quad Power Supply Sequencer ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Fully Sequence and Monitor Four Supplies – Six with Minimal External Circuitry Cascadable for Additional Supplies Power Off in Reverse Order or Simultaneously Charge Pump Drives External MOSFETs Drives Power Supply Shutdown Pins with No External Pull-Up Resistors 10µA Output Current Allows Soft-Starting of Supplies Done Indicator for Both Power On and Power Off Adjustable Time Delay Between Power Supplies Power Good Timer Power Supply Voltage Monitoring and Power Sequence Error Detection and Reporting Available in a 16-Lead Narrow SSOP Package The LTC®2924 is a power supply sequencer designed for use with external N-channel MOSFETs or power supplies with shutdown pins. Four power supplies can be fully sequenced by a single LTC2924 and up to five supplies can be sequenced to a sixth master supply. The LTC2924 requires a minimum of external components, using only two feedback resistors per sequenced power supply and a single resistor to set hysteresis. An internally regulated charge pump provides gate drive voltages for external logic and sub-logic-level MOSFETs. Adding a single capacitor enables an adjustable time delay between power supplies during both Power On and Power Off sequencing. A second capacitor can be added to enable a power good timer for detecting the failure of any power supply to turn on within the selected time. Errors in power supply sequencing and the control input are detected and reported at the FAULT output. The LTC2924 features precision input comparators which can provide 1% accuracy in monitoring power supply voltages. Multiple LTC2924s may be easily cascaded to sequence a virtually unlimited number of power supplies. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. APPLICATIO S ■ ■ Sequenced Power Supplies for ASICs with Multiple I/O and Core Voltages Latch-Up Prevention in Systems with Multiple Power Supplies 3.3V SHDN 1V Q2 5V 5V SHDN 3V Q1 VCC OUT1 IN1 IN2 IN3 IN4 5V EARLY 10k SYSTEM CONTROLLER 10k 150nF 150nF U TYPICAL APPLICATIO VON = 2.64V VOFF = 1.98V VON = 0.93V VOFF = 0.915V VON = 3.97V VOFF = 2.97V VON = 2.79V VOFF = 2.73V 6.04k 100k 1.62k 66.5k 2V/DIV 5V/DIV 2V/DIV 5V/DIV 10ms/DIV 2924 TA01b 0.1µF OUT2 OUT3 OUT4 ON LTC2924 DONE FAULT TMR PGT 2V/DIV 1.69k 18.2k 3.09k 20k 5V/DIV HYS/CFG GND 49.9k Q1-Q4: IRL3714S ALL RESISTORS 1% 2V/DIV 5V/DIV 2924 TA01a U Power-Up Sequence 5V 3.3V 3V 1V DONE TMR ON FEATURES DESCRIPTIO U Power-Down Sequence 5V 3.3V 3V 1V DONE TMR ON 10ms/DIV 2924 TA01c 2924fa 1 LTC2924 (Note 1) Supply Voltage (VCC) ................................ –0.3V to 6.5V Input Voltages ON, IN1-IN4 ............................... – 0.3V to VCC + 0.3V PGT, TMR, HYS/CFG .................. – 0.3V to VCC + 0.3V Open-Drain Output Voltages FAULT, DONE .............................. –0.3V to VCC + 0.3V Output Voltages (OUT1 - OUT4) (Note 5).............. –0.3V to VCC + 4.5V Operating Temperature Range LTC2924C ................................................ 0°C to 70°C LTC2924I ............................................ –40°C to 85°C Storage Temperature Range................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C TOP VIEW IN1 IN2 IN3 IN4 OUT1 OUT2 OUT3 OUT4 1 2 3 4 5 6 7 8 16 ON 15 HYS/CFG 14 TMR 13 GND 12 PGT 11 VCC 10 DONE 9 FAULT ORDER PART NUMBER LTC2924CGN LTC2924IGN GN PART MARKING 2924 2924I GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 130°C/W Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 3V to 6V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS Supply VCC Input Supply Range ICC Input Supply Current ON Threshold VON(TH) ON, Low to High Threshold VOFF(TH) ON, High to Low Threshold IN1-IN4 Threshold VON(TH) IN1-IN4 Low to High Threshold VOFF(TH) IN1-IN4 High to Low Threshold ON, IN1-IN4 Characteristics VFAULT ON, IN1-IN4 High Speed Low Fault Threshold ION(HYS) ON, IN1-IN4 Hysteresis Current Range VON ≥ VON(TH) (Note 2) ION(ERROR) ON, IN1-IN4 Hysteresis Current Error 1 – (ION(HYS)/(0.5/RHYS)), VON(TH) = 1V 0.5µA ≤ ION < 25µA 25µA ≤ ION ≤ 50µA ILEAK ON, IN1-IN4 Leakage (Below Threshold) VON(TH) = 0.5V VON(HYS) ON, IN1-IN4 Minimum Hysteresis Voltage IHYS • RIN (Note 6) OUT1-OUT4 Characteristics VOUT(EN) OUT1-OUT4 Gate Drive Voltage IOUT(EN) OUT1-OUT4 On Current ROUT(OFF) OUT1-OUT4 Off Resistance to GND HYS Characteristics RHYS HYS Current Programming Resistor Range VHYS HYS Programming Voltage IOUTn = 0 OUTn On, VOUT = (VCC + 4V) OUTn Off, IOUT = 2mA (Notes 2, 3) RHYS Tied to GND RHYS Tied to VCC MIN ● ● ● ● ● ● ● ● ● ● ● ● TYP MAX 6 3 0.6121 0.6135 0.6142 0.6148 0.48 50 ±22 ±10 ±100 UNITS V mA V V V V V µA % % nA mV V µA Ω Ω V V 2924fa 3 1.5 0.6000 0.6014 0.6020 0.6026 0.33 0.5 0.6060 0.6074 0.6081 0.6087 0.4 2 4 VCC + 4.5 8.6 ● ● 10 VCC + 6 11.2 240 1M 10k 0.5 VCC – 0.5 2 U W U U WW W ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO LTC2924 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER TMR Characteristics ITMR Timer Pin Output Current VTH(HI) Timer High Voltage Threshold PGT Characteristics IPGT Power Good Timer Pin Output Current VPGT Power Good Timer Fault Detected Voltage Threshold DONE Characteristics DONE Pin Pull-Down Resistance to GND RD(LO) DONE Pin Off Leakage Current ID(HI) FAULT Characteristics   RFAULT (LO) FAULT Pin Pull-Down Resistance to GND IFAULT(HI) VFAULT(HI) VFAULT(LO) RF(EXT) tFAULT tFAULT(MIN) FAULT Pin Off Leakage Current The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 3V to 6V, unless otherwise noted. CONDITIONS Timer On, VTMR ≤ 0.9V VCC = 5V Power Good Timer On, VPGT ≤ 0.9V VCC = 5V ● MIN 4 0.93 4 0.93 TYP 5 1 5 1 MAX 6 1.07 6 1.07 UNITS µA V µA V ● DONE = Low, I = 2mA  DONE = High FAULT Being Pulled Low Internally, I = 2mA FAULT High ● ● ● ● ● ● ● ● 100 15 400 2 1.6 0.6 10 1 1 Ω µA Ω µA V V kΩ µs µs Voltage Above Which an Externally Generated FAULT Condition Will Not be Detected Voltage Below Which an Externally Generated FAULT Condition Will be Detected External Pull-Up Resistance Externally Commanded FAULT Below VFAULT(LO) to OUT1-OUT4 Pull-Down On Delay Externally Commanded FAULT Minimum Time (Note 4) Below VFAULT(LO) Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Hysteresis current must be 500nA minimum. Hysteresis current may exceed 50µA, but accuracy is not guaranteed. Note 3: HYS/CFG pin must be pulled to GND or VCC with an external resistor. See Applications Information for details. Note 4: Determined by design, not production tested. External circuits pulling down on the FAULT pin must maintain the signal below VFAULT(LO) for ≥1µs. Note 5: Internal circuits may drive the OUTn pins higher than the Absolute Maximum Ratings. Note 6: RIN is the parallel combination of the two resistors forming the resistive divider connected to the ON and IN1-IN4 pins. TYPICAL PERFOR A CE CHARACTERISTICS 2.3 2.1 1.9 VOUT (V) ICC (mA) 1.7 1.5 1.3 1.1 0.9 3 3.5 4 ON LOW ON HIGH ICC vs VCC IOUT1-4 = –10µA RHYS = 51k 6 4 2 VOUT (V) 4.5 VCC (V) 5 UW 5.5 14 12 10 8 VOUT(EN) vs IOUT VCC = 6V 12 11 VOUT(EN) vs VCC IOUT1-4 < 1µA VCC = 3V 10 9 8 ONE OUTPUT DRIVING CURRENT 0 2 4 6 IOUT (µA) 8 10 12 2924 G02 6 2924 G01 0 7 2 3 4 VCC (V) 5 6 2924 G03 2924fa 3 LTC2924 TYPICAL PERFOR A CE CHARACTERISTICS 55 50 RFAULT AT 2mA (Ω) 5 VCC (V) 2924 G04 RDONE vs VCC RDONE AT 2mA (Ω) 45 40 35 30 3 45 40 35 ISAT (mA) 30 25 20 15 OUTn (Off) ISAT vs Temperature VOUT = 5V VCC = 6V ISAT (mA) 10 20 40 60 –60 –40 –20 0 TEMPERATURE (°C) 4 UW 4 200 180 160 140 120 100 80 RFAULT vs VCC 6 3 4 VCC (V) 5 6 2924 G05 35 OUTn (Off) ISAT vs VCC VOUT = 5V 30 25 20 VCC = 3V 15 10 2.5 80 100 3 3.5 4 4.5 VCC (V) 5 5.5 6 6.5 2924 G06 2924 G07 2924fa LTC2924 PI FU CTIO S IN1-IN4 (Pins 1, 2, 3, 4): Sequenced Power Supply Monitor Input. Connect this pin to an external resistive divider between each sequenced power supply and GND. During Power On sequencing, 0.61V (typ) at this pin indicates that the sequenced power supply (enabled with each of the OUT1-OUT4 pins) has reached the desired Power On sequence voltage. A hysteresis current (programmed by the HYS pin) is sourced out of each of the IN1-IN4 pins after the 0.61V threshold is detected. During the Power Off sequence, 0.61V at this pin indicates that the sequenced power supply has reached the desired Power Off voltage. The hysteresis current is removed after the 0.61V threshold is detected. OUT1-OUT4 (Pins 5, 6, 7, 8): Sequenced Power Supply Enable. Connect this pin to the shutdown pin or an external series N-channel MOSFET gate for each power supply being sequenced. (A low at this pin means the sequenced power supply is commanded to turn off.) When disabled, each output is connected to GND with a resistance of