ISL6146AFUZ-T7A

DATASHEET ISL6146 FN7667 Rev 5.00 Aug 17, 2015 Low Voltage OR-ing FET Controller The ISL6146 represents a family of OR-ing MOSFET controllers capable of OR-ing voltages from 1V to 18V. Together with suitably sized N-channel power MOSFETs, the ISL6146 increases power distribution efficiency when replacing a power OR-ing diode in high current applications. It provides gate drive voltage for the MOSFET(s) with a fully integrated charge pump. The ISL6146 allows users to adjust with external resistor(s) the VOUT - VIN trip point, which adjusts the control sensitivity to system power supply noise. An open drain FAULT pin will indicate if a conditional or FET fault has occurred. The ISL6146A and ISL6146B are optimized for very low voltage operation, down to 1V with an additional independent bias of 3V or greater. The ISL6146C provides a voltage compliant mode of operation down to 3V with programmable undervoltage lock out and overvoltage protection threshold levels. The ISL6146D and ISL6146E are like the ISL6146A and ISL6146B respectively, but do not have conduction state reporting via the fault output. TABLE 1. KEY DIFFERENCES BETWEEN PARTS IN FAMILY PART NUMBER Features • OR-ing down to 1V and up to 20V with ISL6146A, ISL6146B, ISL6146D and ISL6146E • Programmable voltage compliant operation with ISL6146C • VIN hot swap transient protection rating to +24V • High speed comparator provides fast 570mV 2. GATE - VIN < 220mV (A, B, C only) Q-PUMP BIAS + VIN VDS FORWARD REGULATOR + - GATE 19mV VOUT REVERSE DETECTION 57mV COMPARATOR + + - ENABLE EN ENABLE * 4A + + UVLO EN/EN 8mA ADJ FLT 3. TEMP > +150°C 4. VBIAS < POR (ISL6146A/B/D/E) 5. VIN OR VOUT < POR (ISL6146C) 6. VIN < VOUT 7. Gate to Drain and Gate to Source Shorts HIGH SPEED COMPARATOR + - OVP VREF + ISL6146A/B/D/E * Connected to BIAS on ISL6146A/B/D/E + - VREF Connected to VOUT on ISL6146C ISL6146C Pin Configuration ISL6146A, ISL6146B, ISL6146D, ISL6146E GATE 1 8 VOUT VIN 2 7 ADJ BIAS 3 6 FAULT 4 5 GND EN ISL6146A/D EN ISL6146B/E ISL6146 (8 LD MSOP/DFN) TOP VIEW ISL6146C GATE 1 8 VOUT VIN 2 7 ADJ UVLO 3 6 FAULT OVP 4 5 GND EPAD on DFN only, connect to GND Pin Descriptions MSOP/ DFN SYMBOL DESCRIPTION 1 GATE Gate Drive output to the external N-Channel MOSFET generated by the IC internal charge pump. Gate turn-on time is typically 0.57V when ON. c. FET G-D or G-S or D-S shorts. d. VIN < PORL2H e. VIN < VOUT f. Over-Temperature Range: 0 to VOUT 7 ADJ Resistor programmable VIN - VOUT Voltage Threshold (Vth) of the High Speed Comparator. This pin is either directly connected to VOUT or can be connected through a 5kΩ to 100kΩ resistor to GND. Allows for adjusting the voltage difference threshold to prevent unintended turn-off of the pass FET due to normal system voltage fluctuations. Range: 0.4 to VOUT 8 VOUT The second sensing node for external FET control and connected to the Load side (OR-ing MOSFET Drain). This is the common connection point for multiple paralleled supplies. VOUT is compared to VIN to determine when the OR-ing FET has to be turned off. Range: 0V to 24V PAD Thermal Pad Connect to GND FN7667 Rev 5.00 Aug 17, 2015 Page 4 of 28 ISL6146 Ordering Information PART NUMBER (Notes 1, 2, 3) PART MARKING TEMP RANGE (°C) PACKAGE (Pb-free) PKG. DWG. # ISL6146AFUZ 6146A -40 to +125 8 Ld MSOP M8.118 ISL6146AFRZ 46AF -40 to +125 8 Ld 3x3 DFN L8.3x3J ISL6146BFUZ 6146B -40 to +125 8 Ld MSOP M8.118 ISL6146BFRZ 46BF -40 to +125 8 Ld 3x3 DFN L8.3x3J ISL6146CFUZ 6146C -40 to +125 8 Ld MSOP M8.118 ISL6146CFRZ 46CF -40 to +125 8 Ld 3x3 DFN L8.3x3J ISL6146DFUZ 6146D -40 to +125 8 Ld MSOP M8.118 ISL6146DFRZ 46DF -40 to +125 8 Ld 3x3 DFN L8.3x3J ISL6146EFUZ 6146E -40 to +125 8 Ld MSOP M8.118 ISL6146EFRZ 46EF -40 to +125 8 Ld 3x3 DFN L8.3x3J ISL6146AEVAL1Z ISL6146A Evaluation Board (If desired with ISL6146D, please contact support) ISL6146BEVAL1Z ISL6146B Evaluation Board (If desired with ISL6146E, please contact support) ISL6146CEVAL1Z ISL6146C Evaluation Board ISL6146DEVAL1Z 1 pair of ISL6146D Mini Development Boards (If desired with ISL6146A, please contact support) ISL6146EEVAL1Z 1 pair of ISL6146E Mini Development Boards (If desired with ISL6146B, please contact support) NOTES: 1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications. 2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 3. For Moisture Sensitivity Level (MSL), please see device information page for ISL6146. For more information on MSL please see techbrief TB363. FN7667 Rev 5.00 Aug 17, 2015 Page 5 of 28 ISL6146 Absolute Maximum Ratings Thermal Information BIAS, VIN, VOUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +24V GATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 40V EN, EN, UVLO, OVP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +24V ADJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VOUT FAULT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VOUT ESD Rating Human Body Model (Tested per JESD22-A114E) . . . . . . . . . . . . . . .2.5kV Machine Model (Tested per JESD22-A115-A) . . . . . . . . . . . . . . . . . 250V Latch-up (Tested per JESD-78B; Class 2, Level A) . . . . . . . . . . . . . . 100mA Thermal Resistance (Typical) JA (°C/W) JC (°C/W) MSOP Package (Notes 4, 7) . . . . . . . . . . . . 140 41 DFN Package (Notes 5, 6) . . . . . . . . . . . . . . 46 5 Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . .+150°C Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C Pb-free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493 Recommended Operating Conditions Bias Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . +3V to +20V OR’d Supply Voltage Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . +1V to BIAS Temperature Range (TA) . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +125°C CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and result in failures not covered by warranty. NOTES: 4. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details. 5. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech Brief TB379. 6. For JC, the “case temp” location is the center of the exposed metal pad on the package underside. 7. For JC, the “case temp” location is taken at the package top center Electrical Specifications temperature range, -40°C to +125°C. SYMBOL VCC = BIAS = 12V, unless otherwise stated. TA = +25°C to +85°C. Boldface limits apply across the operating PARAMETERS TEST CONDITIONS MIN (Note 8) TYP MAX (Note 8) UNITS 1.9 2.5 2.95 V BIAS PORL2H POR Rising PORHYS POR Hysteresis BIAS Rising, GATE Rising 189 mV IBIAS_en_18 ISL6146A/B/D/E BIAS Current BIAS, VIN = 18V, ADJ, VOUT = 16.98V, enabled 3.6 5 mA IVIN_en_18 ISL6146A/B/D/E VIN Current BIAS, VIN = 18V, ADJ, VOUT = 16.98V, enabled 25 40 µA IVIN_en_18 ISL6146C VIN Current VIN = 18V, ADJ, VOUT = 16.98V, enabled 3 4.5 mA IVOUT_en_18 ISL6146A/B/D/E VOUT Current BIAS, VIN = 18V, VOUT = 16.98V, enabled 14 20 µA VOUT_en_18 ISL6146C VOUT Current VIN = 18V, VOUT = 16.98V, enabled 400 500 µA IBIAS_den_18 ISL6146A/B/D/E BIAS Current BIAS, VIN = 18V, ADJ, VOUT = 16.98V, disabled 1.7 3 mA IVIN_den_18 ISL6146A/B/D/E VIN Current BIAS, VIN = 18V, ADJ, VOUT = 16.98V, disabled 27 37 µA IVIN_den_18 ISL6146C VIN Current VIN = 18V, ADJ, VOUT = 16.98V, disabled 1.3 1.5 mA IVOUT_den_18 ISL6146A/B/D/E VOUT Current BIAS, VIN = 18V, VOUT = 16.98V, disabled 14 20 µA IVOUT_den_18 ISL6146C VOUT Current VIN = 18V, VOUT = 16.98V, disabled 385 500 µA BIAS to GATE Delay BIAS > PORL2H to GATE Rising 150 210 µs VGH_3 Charge Pump Voltage VIN, BIAS = 3V VIN - VOUT > VFWD_VR VIN + 5V VIN + 7V VIN + 10.5V V VGH_12 Charge Pump Voltage VIN, BIAS = 12V VIN - VOUT > VFWD_VR VIN + 9V VIN + 10V VIN + 17.5V V VGH_18 Charge Pump Voltage VIN, BIAS = 18V VIN - VOUT > VFWD_VR VIN + 9V VGL Low Voltage Level VIN - VOUT < 0V IPDL Low Pull-Down Current VIN = 12V, VOUT = 12.2V ADJ = 11V IPDH High Pull-Down Current VIN falling from 12V to 10V in 2µs ttoff Fast Turn-off Time VIN = VBIAS = 12V, VGATE = 18V to 10V, CGATE = 57nF tBIAS2GTE GATE FN7667 Rev 5.00 Aug 17, 2015 VIN +10V VIN + 18V V 0 0.1 V 5 8.4 13 mA 3.5 6.5 65 A 130 ns Page 6 of 28 ISL6146 Electrical Specifications VCC = BIAS = 12V, unless otherwise stated. TA = +25°C to +85°C. Boldface limits apply across the operating temperature range, -40°C to +125°C. (Continued) SYMBOL PARAMETERS TEST CONDITIONS MIN (Note 8) TYP MAX (Note 8) UNITS 80 µs ttoffs Slow Turn-off Time VIN = VBIAS = 12V, VGATE = 18V to 10V, CGATE = 57nF 58 ION Turn-on Current BIAS = 12V, VG = 0V 1 mA BIAS = 12V, VG = 20V 0.15 mA VVG_FLTr GATE to VIN Rising Fault Voltage GATE > VIN, enabled, FLT output is high. (Does not apply to ISL6146D and ISL6146E) 320 440 560 mV VVG_FLTf GATE to VIN Falling Fault Voltage GATE > VIN, enabled, FLT output is low. (Does not apply to ISL6146D and ISL6146E) 140 220 300 mV CONTROL AND REGULATION I/O VRr Reverse Voltage Detection Rising VOUT Threshold VOUT rising 35 57 79 mV VRf Reverse Voltage Detection Falling VOUT Threshold VOUT falling 10 30 51 mV tRs Reverse Voltage Detection Response Time VFWD_VR Amplifier Forward Voltage Regulation VOS_HS VTH(HS5k) VTH(HS100k) tHSpd 10 ISL6146 controls voltage across FET VDS to VFWD_VR during static forward operation at loads resulting in Id*rDS(ON) < VFWD_VR HS Comparator Input Offset Voltage ADJ Adjust Threshold with 5k to GND RADJ = 5kΩ to GND ADJ Adjust Threshold with 100k to GND RADJ = 100kΩ to GND HS Comparator Response Time 11 19 28 mV -14 0.7 14 mV 0.57 0.8 1.1 V 10 40 95 mV VOUT > VIN, 1ns transition, 5V differential VFWD_FLT VIN to VOUT Forward Fault Voltage VIN > VOUT, GATE is fully on, FLT output is low VFWD_FLT_HYS VIN to VOUT Forward Fault Voltage Hysteresis VIN > VOUT, GATE is fully on, FLT output is high IFLT_SINK FAULT Sink Current BIAS = 18V FAULT = 0.5V, VIN < VOUT, VGATE = VGL IFLT_LEAK FAULT Leakage Current FAULT = “VFLT_H”, VIN > VOUT, VGATE = VIN + VGQP tFLT_L2H FAULT Low to High Delay tFLT_H2L FAULT High to Low Delay µs 170 330 450 ns 570 mV 44 mV 9 mA FAULT OUTPUT 5 0.04 10 µA GATE = VGQP to FAULT output is high 10 23 µs GATE = VIN to FAULT output is low 1.7 3 µs 606 631 mV ENABLE UVLO/OVP/ADJ INPUTS VthRa VthR_hysa VthFb VthF_hysb VthFc VthF_hysc VthRc ISL6146A/D EN Rising Vth 580 ISL6146A/D EN Vth Hysteresis ISL6146B/E EN Falling Vth -90 580 ISL6146B/E EN Vth Hysteresis ISL6146C OVP Falling Vth 631 +90 580 ISL6146C OVP Vth Hysteresis ISL6146C UVLO Rising Vth 606 mV 606 mV 631 +90 580 606 mV mV mV 631 mV VthR_hysc ISL6146C UVLO Vth Hysteresis -90 tEN2GTER EN/UVLO Rising to GATE Rising Delay 10 12 µs EN/OVP Falling to GATE Rising Delay 9 12 µs FN7667 Rev 5.00 Aug 17, 2015 mV Page 7 of 28 ISL6146 Electrical Specifications VCC = BIAS = 12V, unless otherwise stated. TA = +25°C to +85°C. Boldface limits apply across the operating temperature range, -40°C to +125°C. (Continued) tEN2GTEF MIN (Note 8) TYP MAX (Note 8) UNITS EN/UVLO Falling to GATE Falling Delay 2 4 µs EN/OVP Rising to GATE Falling Delay 2 4 µs SYMBOL PARAMETERS TEST CONDITIONS Ren_h ENABLE Pull-down Resistor ISL6146A, ISL6146D 2 MΩ Ren_l ENABLE Pull-up Resistor ISL6146B, ISL6146E 2 MΩ Vadj ADJ Pin Voltage RADJ 5kΩ to 100kΩ 0.4 V Radj ADJ Pull-up Resistor Internal ADJ pull-up resistor to VOUT 3.85 MΩ OTS Over-temperature Sense Fault signals in operation 140 °C 20 °C 125 °C OTSHYS HTS Over-temperature Sense Hysteresis High Temperature Sense Fault signals upon enabling NOTE: 8. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design. FN7667 Rev 5.00 Aug 17, 2015 Page 8 of 28 ISL6146 Typical Performance Curves 4.0 3.0 2.0 18V DISABLED 12V DISABLED 3V DISABLED 35 -40 25 85 TEMPERATURE (°C) 3V ENABLED 25 20 18V DISABLED 12V DISABLED 3V DISABLED VOUT CURRENT 10 125 FIGURE 3. ISL6146A/B/D/E BIAS AND ISL6146C VIN CURRENT vs TEMPERATURE -40 25 85 TEMPERATURE (°C) 125 FIGURE 4. ISL6146A/B/C/D/E VIN AND VOUT CURRENT vs TEMPERATURE 35 2.60 BIAS = 18V 2.55 30 2.50 BIAS = 12V 25 POR Vth RISING 2.45 VPOR Vth (V) HARD ON GATE VOLTAGE (V) 12V ENABLED 30 15 1.5 1.0 18V ENABLED VIN CURRENT VIN/VOUT CURRENT (mA) IBIAS/IVIN CURRENT (mA) 3.5 2.5 40 18V ENABLED 12V ENABLED 3V ENABLED 20 15 BIAS = 3V 10 2.40 2.35 2.30 2.25 POR Vth FALLING 2.20 2.15 5 2.10 0 -40 25 85 2.05 125 -40 85 125 FIGURE 6. POR Vth RISING AND FALLING VOLTAGE FIGURE 5. GATE VOLTAGE vs TEMPERATURE 0.74 0.70 0.72 0.65 EN DEASSERT RISING Vth 0.70 EN ASSERT RISING Vth 0.68 0.55 EN Vth (V) 0.60 EN Vth (V) 25 TEMPERATURE (°C) TEMPERATURE (°C) EN DEASSERT FALLING Vth 0.50 0.66 0.64 0.62 0.60 EN ASSERT FALLING Vth 0.58 0.45 0.56 0.40 -40 25 85 TEMPERATURE (°C) FIGURE 7. ISL6146A/D EN Vth vs TEMPERATURE FN7667 Rev 5.00 Aug 17, 2015 125 0.54 -40 25 85 125 TEMPERATURE (°C) FIGURE 8. ISL6146B/E EN Vth vs TEMPERATURE Page 9 of 28 ISL6146 Typical Performance Curves (Continued) 750 1.3 VG = 0V OVP RISING GATE TURN-ON CURRENT (mA) OVP AND UVLO Vth (mV) 700 650 600 UVLO RISING AND OVP FALLING 550 500 450 UVLO FALLING -40 25 85 TEMPERATURE (°C) 1.1 0.9 0.7 0.5 0.3 0.1 125 7.0 10 6.5 9 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 -40 25 85 TEMPERATURE (°C) 7 6 5 4 3 2 1 0 125 -40 25 85 TEMPERATURE (°C) 125 FIGURE 12. GATE SLOW TURN-OFF CURRENT 56.0 45 55.5 40 55.0 RESPONSE TIME (µs) REVERSE DETECTION VOLTAGE (mV) 125 8 FIGURE 11. GATE HARD TURN-OFF CURRENT 54.5 54.0 53.5 53.0 35 30 25 20 52.5 52.0 25 85 TEMPERATURE (°C) FIGURE 10. GATE TURN-ON CURRENT VIN = 12V GATE PULL-DOWN CURRENT (mA) GATE PULL-DOWN CURRENT (A) FIGURE 9. ISL6146C UVLO/OVP Vth vs TEMPERATURE -40 -40 25 85 TEMPERATURE (°C) 125 FIGURE 13. INCREASING REVERSE VOLTAGE DETECTION Vth FN7667 Rev 5.00 Aug 17, 2015 15 -40 25 85 TEMPERATURE (°C) 125 FIGURE 14. REVERSE VOLTAGE RESPONSE TIME Page 10 of 28 ISL6146 Typical Performance Curves (Continued) 3 300 280 260 RESPONSE TIME (ns) OFFSET VOLTAGE (mV) 2 1 0 -1 240 220 200 180 160 140 -2 120 -3 -40 25 85 TEMPERATURE (°C) 100 125 FIGURE 15. HIGH SPEED COMPARATOR OFFSET VOLTAGE 700 1.000 600 0.999 RELATIVE % HS COMP ADJUST VTH (mV) 1.001 RADJ TO GND = 5kΩ 500 400 300 200 0.998 0.997 0.996 0.995 100 RADJ TO GND = 100kΩ -40 25 85 TEMPERATURE (°C) 0.994 125 FIGURE 17. HS COMPARATOR ADJUSTABLE Vth 0.993 3 12 BIAS VOLTAGE (V) 18 FIGURE 18. EN/EN/OVP/UVLO Vth DELTA vs BIAS VOLTAGE NORMALIZED TO BIAS = 12V 21.0 465 20.8 460 20.6 VIN - VOUT FAULT VTH (mV) VIN TO VOUT FWD VOLTAGE REG (mV) 125 1.002 800 20.4 20.2 20.0 19.8 19.6 19.4 455 450 445 440 435 430 425 19.2 19.0 25 85 TEMPERATURE (°C) FIGURE 16. HIGH SPEED COMPARATOR RESPONSE TIME 900 0 -40 -40 25 85 TEMPERATURE (°C) FIGURE 19. FORWARD VOLTAGE REGULATION FN7667 Rev 5.00 Aug 17, 2015 125 420 -40 25 85 TEMPERATURE (°C) 125 FIGURE 20. VIN TO VOUT FORWARD FAULT VOLTAGE Page 11 of 28 ISL6146 Typical Performance Curves (Continued) GATE 2 GATE1 GATE 2 GATE1 IIN2 IIN1 IIN1 IIN2 FIGURE 21. ISL6146C SLOW RAMP CONNECT 12V OR-ing GATE1 GATE 2 FIGURE 22. ISL6146C SLOW RAMP DISCONNECT 12V OR-ing GATE 2 GATE1 IIN2 IIN1 IIN2 IIN1 FIGURE 23. ISL6146C HOT SWAP CONNECT 12V OR-ing FIGURE 24. ISL6146C HOT DISCONNECT 12V OR-ing GATE EN/UVLO FIGURE 25. ISL6146A/D EN/ISL6146C UVLO TO GATE ON DELAY FN7667 Rev 5.00 Aug 17, 2015 GATE EN/UVLO FIGURE 26. ISL6146A/D EN/ISL6146C UVLO TO GATE OFF DELAY Page 12 of 28 ISL6146 Typical Performance Curves (Continued) GATE GATE EN EN FIGURE 27. ISL6146B/E EN TO GATE ON DELAY FIGURE 28. ISL6146B/E EN TO GATE OFF DELAY GATE OVP OVP GATE FIGURE 29. ISL6146C OVP TO GATE ON DELAY VIN RISING THROUGH BOTH THE PROGRAMMED UVLO AND OVP LEVELS. GATE TURNS-ON AS VIN EXCEEDS 10V THEN TURNS-OFF AS VIN EXCEEDS 15V FIGURE 30. ISL6146C OVP TO GATE OFF DELAY VIN FALLING THROUGH BOTH THE PROGRAMMED OVP AND UVLO LEVELS. GATE TURNS-ON AS VIN > 13V THEN TURNS-OFF AS VIN > 8.3V VIN GATE FIGURE 31. ISL6146C RISING VIN, UVLO AND OVP FUNCTION FN7667 Rev 5.00 Aug 17, 2015 GATE VIN FIGURE 32. ISL6146C FALLING, VIN OVP AND UVLO FUNCTION Page 13 of 28 ISL6146 Typical Performance Curves (Continued) VIN RISING TO VFWD_FLT 35 40 30 35 25 % OF DISTRIBUTION % OF DISTRIBUTION FIGURE 39. VIN HOT SWAPPED TO GATE WITH BIAS = 12V NO LOAD 20 15 10 25 20 15 10 5 0 30 5 -1 0 1 2 3 4 5 HS COMP ADJUST VTH (mV) 6 7 FIGURE 41. HIGH SPEED COMPARATOR OFFSET VOLTAGE DISTRIBUTION 0 17 18 19 20 VFWD_VR (mV) 21 22 FIGURE 42. FORWARD REGULATION VOLTAGE DISTRIBUTION 40 35 VDS % OF DISTRIBUTION 30 + 0V VR 25 tHSpd 20 15 20V VGATE 10 5 0 50 52 54 56 58 60 62 64 66 68 VRr (mV) FIGURE 43. REVERSE DETECTION RISING VOLTAGE DISTRIBUTION FN7667 Rev 5.00 Aug 17, 2015 12.6V VBIAS = VIN = 12V tOFF FIGURE 44. FAST RAMP REVERSE PROTECTION TIMING DIAGRAM Page 15 of 28 ISL6146 Typical Performance Curves (Continued) FLT FLT GATE GATE VIN FIGURE 45. ISL6146A FLT RESPONSE TO NON-CONDUCTION FN7667 Rev 5.00 Aug 17, 2015 VIN FIGURE 46. ISL6146D FLT RESPONSE TO NON-CONDUCTION Page 16 of 28 ISL6146 Functional Description Functional Overview In a redundant power distribution system, similar potential and parallel power supplies each contribute to the load current through various active and passive current sharing schemes. Typically, OR-ing power diodes are used to protect against reverse current flow in the event that one of the power supplies falls below the common bus voltage or develops a catastrophic failure. However, using a discrete OR-ing diode solution has some significant drawbacks. The primary downside is the increased power dissipation loss in the OR-ing diodes as system power requirements increase. At the lowest voltages where the ISL6146 is designed for use, the voltage distribution losses across an OR-ing diode can be a significant percentage, in some cases approaching 70%. Another disadvantage when using an OR-ing diode is failure to detect a shorted or opened current path, which jeopardizes system power availability and reliability. An open diode may reduce the system to a single point of failure while a shorted diode eliminates the system’s power protection. Using an active OR-ing FET controller, such as the ISL6146, helps with these potential issues. The use of a low on-resistance FET as the OR-ing component allows for a more efficient system design as the voltage across the FET is much lower than that across a forward biased diode. Additionally, the ISL6146 has a dedicated fault (FAULT) output pin that indicates when there is a conditional or FET fault short providing the diagnostic capability that a diode is unable to. The ISL6146 is designed to OR together voltages as low as 1V when supplied with a separate bias supply of 3V or greater. Otherwise, the ISL6146 is designed to be biased from and OR voltages across the 3V to 20V nominal supply range. In a single FET configuration as voltage is first applied to a VIN pin, the FET body diode conducts providing all the ISL6146s connected on a common bus circuit, bias via the VOUT pins. As individual power supply voltages ramp up in excess of the rising POR threshold, the ISL6146’s internal charge pump activates to provide a floating gate drive voltage for the external N-channel OR-ing MOSFET, thus turning the FETs on once VIN > VOUT. The ISL6146 continuously monitors the drain and source of the OR-ing FET and provides a reverse voltage (N-channel MOSFET VOUT - VIN) detection threshold (VR) that, when exceeded, indicates a reverse current condition. Once this threshold is exceeded, the ISL6146 turns off the OR-ing FET by pulling down the GATE pin to GND. The ISL6146 also provides high speed VOUT > VIN transient protection as in the case of a catastrophic VIN failure. The ISL6146 additionally provides for adjustment of the VIN - VOUT reverse voltage Vth (VR Vth) via the ADJ pin of the ISL6146 with an external resistor to GND. This allows adjusting the VIN - VOUT voltage threshold level to compensate for normal system voltage fluctuations, thus eliminating unnecessary reaction by the ISL6146. The total VIN - VOUT VR Vth is the sum of both the internal offset and the external programmed VR Vth. FN7667 Rev 5.00 Aug 17, 2015 In the event of a VOUT > VIN condition, the ISL6146 responds either with a high or low current pull-down on the GATE pin depending on whether the High Speed comparator (HSCOMP) has been activated or not. The HSCOMP determines if the VR occurred within 1μs, by continuously monitoring the FET VDS and if so, the high pull-down current is used to turn off the OR-ing FET. In the event of a falling VIN transition in VOUT relationship is established again, the ISL6146 again turns on the FET. The FAULT pin is an open drain, active low output indicating that a fault or specific condition has occurred, these include: • GATE is OFF (GATE < VIN+0.2V). Lack of conduction, not a fault, just not on. ISL6146D and ISL6146E do not respond to this condition • Faults resulting in VIN - VOUT > 0.57V when ON • An open FET resulting in body diode conduction • Excessive current through FET • FET Faults monitored and reported include - G-D, gate unable to drive to Q-pump voltage - G-S, gate unable to drive to Q-pump voltage - D-S shorts, when GATE is OFF VDS < 2V - VIN < POR - Missing VIN - VIN shorted to GND On the ISL6146C version, a conditional fault is also signalled if the VIN is not within the programmed UVLO and OVP levels. The ISL6146 has an on-chip over-temperature fault threshold of ~+140°C with a 20°C hysteresis. Although the ISL6146 itself produces little heat, it senses the environment in which it is, likely including a near by FET. The ISL6146A/D and ISL6146B/E are functional variants with an enabling input of either polarity. This feature is used when the need to interrupt the current path via signaling is necessary. This is accomplished by implementing two FETs in series so that there is a body diode positioned to block current in either direction. This functionality is considered an additional enhancement to the OR-ing diode it replaces. The ISL6146C employs the use of a programmable Undervoltage Lock Out (UVLO) and a programmable Overvoltage Protection (OVP) input. This allows the GATE to only turn-on when the monitored voltage is between the programmed lower and upper levels. This application would use the back-to-back FET configuration. In the event that the current path does not need to be interrupted then the EN, UVLO and OVP inputs can all be overridden. The ISL6146D and ISL6146E are variants of the ISL6146A and ISL6146B respectively, the difference being the former do not respond to a nonconduction condition (when enabled and VIN>VOUT, the GATE is not on) unlike the latter that do signal a fault. Page 17 of 28 ISL6146 Applications Information Power-up Considerations BIAS AND VIN CONSTRAINTS Upon power-up when the VIN supply is separate from the BIAS supply, the BIAS voltage must be greater or equal to the VIN voltage at all times. When using a single supply for both the ISL6146 bias and the OR-ing supply, the VIN and BIAS pins can be configured with a low value resistor between the two pins to provide some isolation and decoupling to support the chip bias even as the OR’d supply experiences voltage droops and surges. Although not necessary to do so, it is a best design practice for particularly noisy environments. FET TO IC LAYOUT RECOMMENDATIONS Connections from the FET(s) to the ISL6146 VIN and VOUT pins must be Kelvin in nature and as close to the FET drain and source PCB pads as possible to eliminate any trace resistance errors that can occur with high currents. This connection placement is most critical to providing the most accurate voltage sensing particularly when the back-to-back FET configuration is used. Likewise, connections from OVP, UVLO and ADJ are also critical to optimize accuracy. ADJUSTING THE HS COMPARATOR REVERSE VOLTAGE THRESHOLD The ISL6146 allows adjustment of the HS Comparator reverse voltage detection threshold (VR Vth), the difference in VOUT - VIN. There are two valid ADJ pin configurations: 1. ADJ connected to VOUT: This makes the HS comparator threshold equal to the intrinsic error in the HS comparator input. This is the default condition and the most likely used configuration. 2. A single resistor is connected from ADJ pin to ground: Making the HS comparator threshold = VOUT - 4k/RADJ. So, for a 100kΩ REXT, HS Comparator threshold = 40mV below VOUT and for a 5kΩ REXT HS comparator threshold = ~800mV below VOUT. The recommended resistor range is 5kΩ to 100kΩ for this voltage adjustment. At power-up, the HS comparator threshold is default set to the internal device error first, and then released to the user programmed threshold after the related circuits are ready. It takes ~20μs for the circuit to switch from the default setting to the user programmed threshold after a POR startup. The current out of the ADJ pin with a resistor to GND is equal to 0.4V/REXT. BACK-TO-BACK FET CONFIGURATION When using the back-to-back FET configuration, the FET choice must be such that the voltage across both FETs at full current loading be less than the minimum forward voltage fault threshold of 400mV to avoid unintended fault notification. FN7667 Rev 5.00 Aug 17, 2015 In this configuration, it may be tempting to use the enable inputs to force a path by switching between the two as opposed to having both paths on, and having the higher voltage source provide current. The problem with that is the timing of the FETs on and off, so that excessive VOUT voltage droop is not introduced if the turn-off happens faster, or before the (or a slower) turn-on momentarily leaves the load with an inadequate power connection. Typical Applications Circuits There are four basic configurations that the ISL6146 can be used in: 1. For voltages >3V where the BIAS and VIN are common 2. For a very low OR-ing voltage, 3V 3. For a voltage window compliant operation and, 4. For a signaled operation where the current path is controlled by an input signal or minimum voltage condition. Each of these configurations can be tailored for the High Speed Comparator (HSCOMP) reverse threshold via the ADJ input being connected either to VOUT or to GND via a resistor as previously explained. Additionally, the voltage window is adjustable for both a minimum and maximum operating voltage via the UVLO and OVP inputs and a resistor divider also explained earlier. Also, soft-start and turn-on and turn-off characteristics can be tailored to suit. The three evaluation platforms provided demonstrate the four basic configurations and provide for the additional tailoring of the various performance characteristics. BIAS VOLTAGE >3V + Q1 C O M M O N + VERY LOW VOLTAGE DC/DC (1V-3V) VIN BIAS EN GATE VOUT P O W E R ADJ ISL6146A FLT B U S GND - + Q2 C O M M O N + VIN VERY LOW VOLTAGE DC/DC (1V-3V) GATE BIAS VOUT P O W E R ADJ ISL6146A FLT EN B U S GND FIGURE 47. LOW VOLTAGE APPLICATION DIAGRAM Page 18 of 28 ISL6146 The circuit shown in Figure 1 on page 1 is the basic circuit used for OR-ing voltages >3V to 20V. The ISL6146A application shown in Figure 47 is the configuration for OR-ing very low voltages of 1V to 3V. Additionally, this application shows the utilization of the ADJ input with a single resistor tied to GND. This provides the user a programmable level of VOUT > VIN before the High Speed (HS) Comparator is activated and the GATE output is pulled down to allow for normal voltage fluctuations in the system. Notice that in both of these circuits, the EN or EN inputs are defaulted to enabled and have no current path on/off control. Failure to do so correctly will result in only body diode conduction and a resulting fault indication. The VIN and VOUT to FET and GND to ADJ connections are drawn to emphasize the Kelvin connection necessary to correctly monitor the voltage across the FET, and for the VR Vth monitor to eliminate any stray resistance effects. Q1 Q2 + + VIN VOUT GATE UVLO VOLTAGE DC/DC 3V-20V ADJ ISL6146C OVP FLT + Q4 C O M M O N + VIN VOLTAGE DC/DC 3V-20V P O W E R B U S GND - Q3 C O M M O N GATE UVLO VOUT ADJ ISL6146C OVP GND FLT P O W E R B U S - FIGURE 48. TYPICAL ISL6146C APPLICATION DIAGRAM DISTRIBUTED VOLTAGE >3V Q1 Q2 + C O M M O N + VERY LOW VOLTAGE DC/DC (1V-BIAS) VIN VOUT GATE BIAS P O W E R ADJ ISL6146A/B GND FLT EN/EN - Q3 ENABLED WHEN SIGNALED + Q4 C O M M O N + VERY LOW VOLTAGE DC/DC (1V-BIAS) VIN GATE VOUT BIAS P O W E R ADJ ISL6146A/B GND - B U S FLT EN/EN ENABLED WHEN SIGNALED B U S FIGURE 49. CONTROLLED ON/OFF APPLICATION DIAGRAM The application diagram in Figure 49 shows the ISL6146A or ISL6146B utilizing the EN or EN pin as a signalled input to open or close the conduction path from power supply to load. This feature can be implemented on OR-ing 1V to 20V but is shown for OR-ing 0.5V when ON fault. Q3 is necessary if VBATT can ever exceed VEXT to prevent current from flowing into VEXT when present. The body diode of Q3 prevents that when Q1 is on regardless of the VBATT voltage. The FN7667 Rev 5.00 Aug 17, 2015 The following 2 circuits are simple single ISL6146 switchover circuits optimized for situations particular to the VBATT and VEXT voltages relative to each other. Figure 50 shows an ISL6146B switchover circuit where VEXT, when present, is the preferred source and VBATT could be lesser or greater than VEXT. This circuit senses the presence of the preferred voltage supply to a programmable threshold level that, when exceeded, VEXT is passed to the output as VBATT is disconnected from the output. Page 19 of 28 ISL6146 ISL6146 bias is pulled from the common drain node to ensure an always adequate bias from either source when the other is absent. Q1 VEXT 3.3V-24V SWITCHED OUTPUT Q2 Use when VBATT > VEXT Q3 disconnects VBATT from output when GATE is off. Q3 VBATT 3.3V-20V VIN GATE ISL6146B EN Figure 52 is a ISL6146A switchover circuit to use where the preferred VEXT source is always greater than the VBATT. Because this is so, there is no need for a 3rd FET for blocking as in Figure 50. Additionally, the preferred VEXT source when present or at a programmed minimum threshold voltage via R1 and R2 divider, will turn on Q2/turn-off Q1 but when absent or not minimally adequate, will do the opposite. In this circuit, with the ISL6146A not connected to the battery, and thus no constant IVIN load on it, which allows for longer battery life. Bias voltage is pulled from the common output to ensure an always adequate IC bias from either source. VOUT FLT BIAS R1 All of the scope shots were taken with a 5A load and 100µF of bulk load capacitance. GND Q1 ADJ R3 VBATT SWITCHED OUTPUT R2 Use when VBATT < VEXT Q2 FIGURE 50. ISL6146B EXTERNAL SWITCHOVER SCHEMATIC VEXT Figure 51 shows operational scope shots of the above circuit. VIN GATE FLT BIAS BATT SUPPLY EXT SUPPLY R1 ISL6146A EN VOUT VOUT ADJ GND R2 FIGURE 53. ISL6146A EXTERNAL SWITCHOVER SCHEMATIC GATE BATT SUPPLY EXT SUPPLY VOUT FIGURE 51. EXTERNAL SUPPLY < BATT SUPPLY CONNECTED BATT SUPPLY EXT SUPPLY GATE VOUT FIGURE 54. EXTERNAL SUPPLY > BATT SUPPLY CONNECTED GATE FIGURE 52. EXTERNAL SUPPLY < BATT SUPPLY DISCONNECTED FN7667 Rev 5.00 Aug 17, 2015 Page 20 of 28 ISL6146 BATT SUPPLY EXT SUPPLY VOUT GATE FIGURE 55. EXTERNAL SUPPLY > BATT SUPPLY DISCONNECTED ISL6146 Evaluation Platforms Description and Use of the Evaluation Boards The three ISL6146 evaluation boards are used to demonstrate the four application configurations discussed earlier. All the boards have ADJ shorted to VOUT with the PCB layout having the component footprints to insert a resistor of choice between ADJ and GND to adjust the HS COMP Vth. Likewise, the VIN is connected to BIAS but these can be separated to provide an adequate BIAS voltage when OR-ing