LTLT

LTC1696 Overvoltage Protection Controller FEATURES s s s DESCRIPTIO s s s s ±2% Overvoltage Threshold Accuracy Low Profile (1mm) ThinSOTTM Package Gate Drive for SCR Crowbar or External N-Channel Disconnect MOSFET Monitors Two Output Voltages Senses Output Voltages from 0.8V to 24V Wide Supply Range: 2.7V to 27V Multifunction TIMER/RESET Pin The LTC®1696 is a standalone power supply overvoltage monitor and protection device designed to protect a power supply load in the event of an overvoltage fault. It monitors two adjustable output voltages. If an overvoltage condition is detected, the output drives either an external SCR crowbar or turns off external back-to-back N-channel MOSFETs, thereby, disconnecting the input voltage from the power supply. Pin 6 offers three functions. By connecting a capacitor to this pin, the internal glitch filter time delay can be programmed. Without the capacitor, the default time delay is determined by an internal capacitor. This pin also serves as a reset input to clear the internal latch after an overvoltage fault condition. By pulling it high, the OUT pin is activated if the FB1 and FB2 voltages remain below the trip threshold. The LTC1696 is available in the low profile (1mm) ThinSOT package. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. APPLICATIO S s s s s Telecommunication Systems Computer Systems Industrial Control Systems Notebook Computers TYPICAL APPLICATIO SCR Crowbar Overvoltage Response VCC 12V POWER SUPPLY VOUT2 5V VOUT1 3.3V R4 232k 1% C1 1nF Q1 2N7002 RESET IOUT 20mA/DIV FB1 0.5V/DIV R2 137k 1% R1 44.2k 1% 1 FB1 TIMER/ 6 RESET LTC1696 TIMER/RESET 2V/DIV 2 GND FB2 5 R3 44.2k 1% 3 SCR 2N6507 C2 0.1µF VCC OUT 4 1696 TA01 U C1 = 1nF 100µs/DIV 1696 TA02 U U 1 LTC1696 ABSOLUTE (Note 1) AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW FB1 1 GND 2 VCC 3 TIMER/ RESET 5 FB2 6 4 OUT Supply Voltage (VCC) ............................................... 28V Input Voltage FB1, FB2 ............................................... – 0.3V to 17V TIMER/RESET .......................................– 0.3V to 17V Operating Temperature Range (Note 2) .. – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER LTC1696ES6 S6 PART MARKING LTLT S6 PACKAGE 6-LEAD PLASTIC SOT-23 TJMAX = 125°C, θJA = 256°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS SYMBOL VCC IVCC VFB IFB VFBHST VLKO PARAMETER Supply Voltage Range Standby Supply Current Active Supply Current FB1, FB2 Feedback Threshold FB1, FB2 Input Current FB1, FB2 Feedback Hysteresis VCC Undervoltage Lockout Low-to-High Transition High-to-Low Transition VCC Undervoltage Lockout Hysteresis TIMER/RESET Reset Low Threshold TIMER/RESET Timer High Threshold TIMER/RESET External Trigger High Threshold TIMER/RESET External Trigger High Current TIMER/RESET Timer Current The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 2.7V ≤ VCC ≤ 27V (Notes 3, 4) unless otherwise noted. CONDITIONS Operating Range FB1, FB2 < VFB FB1, FB2 > VFB, COUT = 1000pF Voltage Going Positive TA ≥ 0°C TA < 0°C q q q q q q MIN 2.7 TYP 170 1.1 MAX 27 540 3.5 0.898 0.907 UNITS V µA mA V V µA mV 0.862 0.853 –1 0.880 0.880 – 0.05 12 High-to-Low Transition FB1, FB2 > VFB q q 1.75 1.64 0.78 1.11 1.35 2.05 1.94 110 0.865 1.185 1.50 260 2.35 2.24 0.95 1.26 1.65 650 22 26 22 26 40 8.0 3.3 0.45 28 28 VLKH VRST VTIM VTRIG ITRIG ITIM FB1, FB2 > VFB FB1, FB2 > VFB FB1, FB2 > VFB FB1, FB2 < VFB FB1, FB2 < VFB, TIMER/RESET = VTRIG FB1 = (VFB + 30mV), FB2 < VFB FB1 = (VFB + 200mV), FB2 < VFB FB2 = (VFB + 30mV), FB1 < VFB FB2 = (VFB + 200mV), FB1 < VFB FB1, FB2 = (VFB + 200mV) 12V ≤ VCC ≤ 27V, FB1, FB2 > VFB, COUT = 1000pF VCC = 3.3V, FB1, FB2 > VFB, COUT = 1000pF FB1, FB2 < VFB, ISINK = 1mA, VCC = 3.3V FB1 > VFB, FB2 < VFB, TIMER/RESET = Open, COUT = 1000pF FB2 > VFB, FB1 < VFB, TIMER/RESET = Open, COUT = 1000pF q q q q q q q q q q q q q q 4 5 4 5 8 4.8 2.7 10 12 10 12 18 6.3 3.2 7 7 VOUTH VOUTL tOVPD1 tOVPD2 OUT High Voltage OUT Low Voltage OUT Propagation Delay for FB1 OUT Propagation Delay for FB2 2 U V V mV V V V µA µA µA µA µA µA V V V µs µs W U U WW W LTC1696 ELECTRICAL CHARACTERISTICS SYMBOL tOVPD1,2 tr IOUTSC PARAMETER OUT Propagation Delay for FB1, FB2 OUT Rise Time OUT Short-Circuit Current The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 2.7V ≤ VCC ≤ 27V (Notes 3, 4) unless otherwise noted. CONDITIONS FB1, FB2 > VFB, TIMER/RESET = Open COUT = 1000pF FB1, FB2 > VFB, COUT = 1000pF 12V ≤ VCC ≤ 27V, FB1, FB2 > VFB, VOUT Shorted to GND VCC = 2.7V, FB1, FB2 > VFB, VOUT Shorted to GND q q q q MIN TYP 6 0.4 MAX 24 3 160 18 UNITS µs µs mA mA 35 2 80 9 Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC1696E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified. Note 4: All typical numbers are given for VCC = 12V and TA = 25°C. 3 LTC1696 TYPICAL PERFOR A CE CHARACTERISTICS Standby Supply Current vs Supply Voltage 200 180 160 SUPPLY CURRENT (µA) SUPPLY CURRENT (mA) TA = 25°C SUPPLY CURRENT (µA) 140 120 100 80 60 40 20 0 0 5 15 20 10 SUPPLY VOLTAGE (V) 25 30 1696 G01 Active Supply Current vs Temperature FB1, FB2 FEEDBACK THRESHOLD VOLTAGE (V) 1.20 0.8814 0.8811 0.8808 0.8805 0.8802 0.8799 0.8796 VCC = 12V COUT = 1000pF TA = 25°C FB1, FB2 FEEDBACK THRESHOLD VOLTAGE (V) 1.15 SUPPLY CURRENT (mA) 1.10 1.05 1.00 0.95 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G04 TIMER Threshold Voltage vs Supply Voltage 1.200 TIMER THRESHOLD VOLTAGE (V) TA = 25°C TIMER THRESHOLD VOLTAGE (V) 1.195 1.190 1.185 1.180 1.175 1.170 1.165 1.160 0 5 20 15 SUPPLY VOLTAGE (V) 10 25 30 1696 G07 TIMER CURRENT (µA) 4 UW Standby Supply Current vs Temperature 200 190 180 170 160 150 140 130 120 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G02 Active Supply Current vs Supply Voltage 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 5 20 15 10 SUPPLY VOLTAGE (V) 25 30 1696 G03 VCC = 12V TA = 25°C COUT = 1000pF FB1, FB2 Feedback Threshold Voltage vs Supply Voltage 0.90 FB1, FB2 Feedback Threshold Voltage vs Temperature VCC = 12V 0.89 0.88 0.87 0.86 0 3 6 9 12 15 18 21 24 27 30 SUPPLY VOLTAGE (V) 1696 G05 0.85 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G06 TIMER Threshold Voltage vs Temperature 1.24 VCC = 12V 20 18 TIMER Current vs Supply Voltage TA = 25°C FB1 AND FB2 OVERDRIVE = 200mV 16 14 FB1 OR FB2 OVERDRIVE = 200mV 12 10 8 1.22 1.20 1.18 1.16 1.14 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G08 0 5 10 15 20 SUPPLY VOLTAGE (V) 25 30 1696 G09 LTC1696 TYPICAL PERFOR A CE CHARACTERISTICS TIMER Current vs Temperature 22 20 VCC = 12V TIMER CURRENT (µA) TIMER CURRENT (µA) 18 16 14 12 10 FB1 OR FB2 OVERDRIVE = 200mV FB1 AND FB2 OVERDRIVE = 200mV TIMER CURRENT (µA) 8 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G10 Glitch Filter Timer vs Feedback Overdrive 25 VCC = 3.3V TA = 25°C GLITCH FILTER TIMER (µs) EXTERNAL TRIGGER TRESHOLD VOLTAGE (V) GLITCH FILTER TIMER (µs) 20 15 FB1 OR FB2 OVERDRIVE 10 FB1 AND FB2 OVERDRIVE 5 0 0 50 150 200 100 FEEDBACK OVERDRIVE (mV) External Trigger Threshold Voltage vs Temperature EXTERNAL TRIGGER THRESHOLD VOLTAGE (V) 1.505 1.500 VCC = 12V RESET THRESHOLD VOLTAGE (V) 0.864 0.862 0.860 0.858 0.856 0.854 0.852 0 5 20 15 SUPPLY VOLTAGE (V) 10 25 30 1696 G17 RESET TRHESHOLD VOLTAGE (V) 1.495 1.490 1.485 1.480 1.475 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G16 UW 1696 G13 TIMER Current vs Feedback Overdrive 20 VCC = 12V TA = 25°C 16 TIMER Current vs Feedback Overdrive VCC = 3.3V TA = 25°C FB1 AND FB2 OVERDRIVE 16 FB1 AND FB2 OVERDRIVE 14 12 FB1 OR FB2 OVERDRIVE 10 8 6 4 12 FB1 OR FB2 OVERDRIVE 8 4 0 0 50 150 200 100 FEEDBACK OVERDRIVE (mV) 250 1696 G11 0 50 100 150 200 FEEDBACK OVERDRIVE (mV) 250 1696 G12 Glitch Filter Timer vs Feedback Overdrive 30 25 20 15 10 5 0 FB1 OR FB2 OVERDRIVE FB1 AND FB2 OVERDRIVE VCC = 12V TA = 25°C External Trigger Threshold Voltage vs Supply Voltage 1.51 1.50 1.49 1.48 1.47 1.46 1.45 1.44 0 5 20 15 10 SUPPLY VOLTAGE (V) 25 30 1696 G15 TA = 25°C 250 0 50 100 150 200 FEEDBACK OVERDRIVE (mV) 250 1696 G14 RESET Threshold Voltage vs Supply Voltage 0.868 0.866 TA = 25°C 0.880 0.875 0.870 0.865 0.860 0.855 0.850 0.845 RESET Threshold Voltage vs Temperature VCC = 12V 0.840 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G18 5 LTC1696 TYPICAL PERFOR A CE CHARACTERISTICS OUT Pin Active Output Voltage vs Supply Voltage 8 OUT PIN ACTIVE OUTPUT VOLTAGE (V) OUT PIN SHORT-CIRCUIT CURRENT (mA) OUT PIN ACTIVE OUTPUT VOLTAGE (V) 7 6 5 4 3 2 1 0 0 TA = 25°C COUT = 1000pF 5 20 15 SUPPLY VOLTAGE (V) 10 OUT Pin Short-Circuit Current vs Temperature 120 OUT PIN SHORT-CIRCUIT CURRENT (mA) 30 VOUT SHORTED TO GND ACTIVE OUTPUT CURRENT (mA) 25 20 VCC = 5V 15 10 VCC = 2.7V 5 0 ACTIVE OUTPUT CURRENT (mA) 100 VCC = 27V 80 VCC = 12V 60 40 VCC = 5V 20 0 –55 –35 –15 VCC = 2.7V 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G22 6 UW 25 1696 G19 OUT Pin Active Output Voltage vs Temperature 6.6 6.5 6.4 6.3 6.2 6.1 6.0 5.9 5.8 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1696 G20 OUT Pin Short-Circuit Current vs Supply Voltage 100 90 80 70 60 50 40 30 20 10 0 0 5 TA = 25°C VOUT SHORTED TO GND 15 20 10 SUPPLY VOLTAGE (V) 25 30 1696 G21 VCC = 12V COUT = 1000pF 30 OUT Pin Active Output Current vs Output Voltage TA = 25°C OUT Pin Active Output Current vs Output Voltage 100 90 80 70 60 50 40 30 20 10 0 VCC = 27V TA = 25°C VCC = 12V 0 0.5 1 1.5 2 2.5 3 3.5 4 OUTPUT VOLTAGE (V) 4.5 5 0 1 4 3 2 5 OUTPUT VOLTAGE (V) 6 7 1696 G24 1696 G23 LTC1696 PI FU CTIO S FB1 (Pin 1): First Feedback Input. FB1 monitors and senses the first supply output voltage through an external resistor divider. This voltage is then compared with an internal reference voltage of 0.88V, which sets the threshold for an overvoltage fault detection. If the sense voltage exceeds the threshold level, the output response time at the OUT pin is dependent on the feedback overdrive above the threshold level. The higher the feedback overdrive, the faster will be the response time. GND (Pin 2): Power Ground. Return path for all device currents. VCC (Pin 3): Power Supply. The pin is connected separately from the power supply output that the chip is monitoring. Its input range is from 2.7V to 27V. The quiescent current is typically 100µA in standby mode when the device is operating at 5V. The quiescent current increases to 170µA when operating at 12V. OUT (Pin 4): Output Current Limit Driver. Capable of delivering continuous current, typically 80mA, at high supplies. The output current decreases with lower supply voltage. This pin directly drives the SCR crowbar at high supply voltage. It can also provide gate drive for an N-channel MOSFET or the base of an NPN transistor, which drives the gate of an external SCR at low supply voltage. It is normally in the inactive low state in the standby mode. In the event of an overvoltage fault condition, the OUT pin is latched into the active high state. The latched active high state is reset by pulling the TIMER/ RESET pin low through an N-channel MOSFET switch or if the supply voltage at the VCC pin goes below the undervoltage lockout threshold voltage of 1.94V. FB2 (Pin 5): Second Feedback Input. FB2 monitors and senses the second supply output voltage through an external resistor divider. This voltage is then compared with an internal reference voltage of 0.88V, which sets the threshold for an overvoltage fault detection. If the sense voltage exceeds the threshold level, the output response time at the OUT pin is dependent on the feedback overdrive above the threshold level. The higher the feedback overdrive, the faster will be the response time. TIMER/RESET (Pin 6): Glitch Filter Timer Capacitor, Reset and External Trigger Input. The external capacitor connected to this pin programs the internal glitch filter time delay. The internal current source used to charge the timer capacitor is typically 10µA with feedback overdrive of less than 20mV above the feedback trip threshold from one feedback input. The current source increases to 12µA when the feedback overdrive increases to more than 100mV. It further increases to 18µA if larger overdrive occurs from both feedback inputs. The default glitch filter time delay without an external timer capacitor is fixed by an internal capacitor of 5pF with the internal reference voltage of 1.185V. The delay reduces with increases in first and second feedback input overdrive. This pin also serves as a reset input to clear the internal latch during an overvoltage fault condition. If pulled low, it resets the active high state of the internal latch. The reset signal to this pin should be an open drain type. This pin can also be driven high externally to activate the OUT pin active high if the FB1 and FB2 voltages remain below the feedback trip threshold. U U U 7 LTC1696 BLOCK DIAGRA VCC 3 GND 2 FB1 1 FB2 5 + + – + – BANDGAP REFERENCE 0.88V GLITCH FILTER LOGIC + – 0.865V APPLICATIO S I FOR ATIO Feedback Inputs VS R2 FB1 R1 LTC1696 The LTC1696 has two feedback inputs that allow monitoring of two output voltages. The trip point of the internal comparator is set by an internal reference of 0.88V with ± 2% accuracy. The output voltage, VS, is sensed through an external resistor divider network (Figure 1). The resistors R1 and R2 values are calculated with the typical trip point of 0.88V. R1 • VS = 0.88 R1 + R2 R2 = ( VS – 0.88) • R1 0.88 As an example, let’s calculate values for R1 and R2 for a 3.3V supply in which an overvoltage indication is required at +10% (3.63V). First, a value for R1 is chosen based on the allowable resistor divider string current. This is determined by power dissipation requirements and possible sensitivity to noise coupling into the resistor divider. In this exercise, assume the resistor divider current is 20µA. R1 is calculated from: 8 – + U W W R4 INTERNAL 5V SUPPLY R2 R3 + + – VREF – R1 4 OUT 2V UVLO 1.185V INTERNAL 5V SUPPLY 10µA + FUNCTION OF FB1 AND FB2 OVERDRIVE 6 TIMER/ RESET 1696 BD UU + – + – VREF = 0.88V Figure 1 LTC1696 APPLICATIO S I FOR ATIO R1 = VFB IDIVIDER = 0.88 V = 44k 20µA The nearest 1% value for R1 is 44.2k. Now, calculating for R2 yields: R2 = 44.2k • (3.63V – 0.88 V ) = 138.1k 0.88 V Choosing the nearest 1% value yields 137k. The chosen values for R1 and R2 yield an overvoltage threshold of 3.608V (+ 9.3%). With worst-case tolerances applied, the minimum overvoltage threshold is 3.481V (+5.5%) and the maximum overvoltage threshold is 3.738V (+13.3%). Reset Function In the event of an overvoltage condition, the OUT pin of the LTC1696 is latched into an active high state. The internal latch is reset by pulling the TIMER/RESET pin low through an external N-channel MOSFET switch or pulling VCC voltage below the UVLO trip point of 1.94V. Glitch Filter Timer The LTC1696 has a programmable glitch filter to prevent the output from entering its active high latched condition if transients occur on the FB1 or FB2 pins. The filter time delay is programmed externally by an external capacitor C1 connected to the TIMER/RESET pin. VCC 3.3V R2 54.9k 1% R1 44.2k 1% Q1 2N3904 R5 470Ω 5% R6 22Ω 5% SCR 2N6507 Figure 2. External SCR with NPN Emitter Follower with Low Voltage Supplies U The time delay is given by: tD = W UU C1• VINT ICHG where VINT is the internal reference voltage of 1.185V and ICHG is the internal current source charging the external capacitor C1. The current source ICHG charging the external timer capacitor is 10µA for small feedback transients and increases to 12µA for large feedback transients (greater than 100mV) from one feedback input. The charging current increases to 18µA for large feedback transients from both feedback inputs. SCR Crowbar The LTC1696 can deliver continuous output current typically 80mA at high supply voltage to trigger an external SCR crowbar in the event of an overvoltage condition as shown in the typical application on the front page of the data sheet. The output current decreases when the supply voltage reduces. It delivers 25mA at a supply voltage of 5V. At a low supply voltage of 3.3V, the output current reduces to 10mA and an external NPN emitter follower is needed to boost the current in order to drive the SCR crowbar as shown in Figure 2. The power dissipation due to the high output current at high supply voltage can potentially exceed the thermal limit of the package. This is avoided by resetting the device rapidly when the external SCR crowbar has been triggered, so that the device is not kept in the active high state for too long. POWER SUPPLY VOUT2 2.5V VOUT1 1.8 V R4 93.1k 1% C1 1nF Q1 2N7002 RESET 1 FB1 TIMER/ 6 RESET LTC1696 2 GND FB2 5 R3 44.2k 1% 3 C2 0.1µF VCC OUT 4 1696 F02 9 LTC1696 APPLICATIO S I FOR ATIO Back-to-Back N-Channel MOSFET A power management circuit that uses the LTC1696 to control external back-to-back N-channel MOSFET at low supply voltage is shown in Figure 3. In standby mode, the drain of the external N-channel MOSFET, Q1, is pulled high R2 38.3k 1% 1.5V R1 44.2k 1% 1 FB1 TIMER/ 6 RESET LTC1696 2 GND VCC 3.3V 3 C2 0.1µF VCC Figure 3. Back-to-Back N-Channel MOSFETs for Low Supply Application 10 U by the power management controller when the LTC1696 OUT pin is in the low state. The LTC1696 drives the gate of Q1 high during an overvoltage fault condition. This pulls the drain of Q1 low and turns off the back-to-back Nchannel MOSFETs. C1 1nF Q2 2N7002 RESET 1.8V R3 R4 44.2k 54.9k 1% 1% PRIMARY INPUT SUPPLY POWER MANAGEMENT CONTOLLER Q1 2N7002 1696 F03 W UU FB2 5 OUT 4 N-CHANNEL ×2 LTC1696 PACKAGE DESCRIPTIO U S6 Package 6-Lead Plastic SOT-23 (LTC DWG # 05-08-1634) (LTC DWG # 05-08-1636) 2.80 – 3.10 (.110 – .118) (NOTE 3) 2.60 – 3.00 (.102 – .118) 1.50 – 1.75 (.059 – .069) (NOTE 3) PIN ONE ID .95 (.037) REF .25 – .50 (.010 – .020) (6PLCS, NOTE 2) A A2 .09 – .20 (.004 – .008) (NOTE 2) 1.90 (.074) REF A1 S6 SOT-23 0401 SOT-23 (Original) A A1 A2 L .90 – 1.45 (.035 – .057) .00 – 0.15 (.00 – .006) .90 – 1.30 (.035 – .051) .35 – .55 (.014 – .021) SOT-23 (ThinSOT) 1.00 MAX (.039 MAX) .01 – .10 (.0004 – .004) .80 – .90 (.031 – .035) .30 – .50 REF (.012 – .019 REF) .20 (.008) DATUM ‘A’ L NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE 4. DIMENSIONS ARE INCLUSIVE OF PLATING 5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 6. MOLD FLASH SHALL NOT EXCEED .254mm 7. PACKAGE EIAJ REFERENCE IS: SC-74A (EIAJ) FOR ORIGINAL JEDEC MO-193 FOR THIN Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 LTC1696 APPLICATIO S I FOR ATIO External Triggering The LTC1696 has a feature which allows the output to be latched into an active high state by pulling the TIMER/ RESET pin high even if both the feedback voltages at the R2 38.3k 1% 1.5V R1 44.2k 1% 1 FB1 TIMER/ 6 RESET LTC1696 2 GND VCC 3.3V 3 C2 0.1µF VCC Figure 4. External Triggering RELATED PARTS PART NUMBER LTC1473 LTC1628 LT1681 LTC1698 LTC1703 LTC1735 LTC1922-1 LTC1960 DESCRIPTION Dual PowerPathTM Switch Driver High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator Dual Transistor Synchronous Forward Controller Secondary Synchronous Rectifier Controller Dual 550k Synchronous 2-Phase Switching Regulator Controller with VID Synchronous Step-Down Switching Regulator Synchronous Phase Modulated Full-Bridge Controller Dual Battery Charger/Selector with SPI Interface COMMENTS For Systems with Multiple DC Sources, VIN Up to 30V, Inrush and Short-Circuit Protection Out-of-Phase Controllers, 3.5V ≤ VIN ≤ 36V, ±1% Output Voltage Accuracy Operation Up to 72V Maximum Optocoupler Feedback with Pulse Transformer Synchronization Two Independent PWM Controllers, Wide Load Current Range, 1.5% Output Accuracy Current Mode, 3.5V ≤ VIN ≤ 36V, 0.5V ≤ VOUT ≤ 5V Output Power Levels from 50W to Several kW, Adaptive DirectSenseTM Zero Voltage Switching Extends Run Time, Reduces Charging Time, Crisis Management Prevents Power Interruption, 36-Pin SSOP PowerPath and DirectSense are trademarks of Linear Technology Corporation. 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 q FAX: (408) 434-0507 q www.linear.com U FB1 and FB2 pins are below the trip threshold of the internal comparator. The output is then reset by pulling the TIMER/RESET pin low. Figure 4 shows a circuit that uses the external triggering function of the LTC1696. 5V D1 1N4148 C1 1nF R5 6.8k 5% FB2 5 R3 44.2k 1% PRIMARY INPUT SUPPLY POWER MANAGEMENT CONTOLLER Q1 2N7002 1696 F04 W UU Q2 2N7002 R4 54.9k 1% RESET Q3 2N7002 TRIGGER 1.8V OUT 4 N-CHANNEL ×2 1696f LT/TP 0701 2K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2001