LTC1981/LTC1982 Single and Dual Micropower High Side Switch Controllers in SOT-23 U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO No External Components Required Internal Voltage Triplers Produce High Side Gate Drive for Logic Level FETs Ultralow Power: 10µA Per Driver ON Current (LTC1982) 20µA ON Current (LTC1981) <1µA Shutdown Current VCC Range: 1.8V to 5V Gate Drive Outputs Driven to Ground During Shutdown Gate Drive Outputs Internally Clamped to 7.5V Max “Gate Drive Ready” Output (LTC1981) Ultrasmall Application Circuit 5-Pin SOT-23 Package (LTC1981) 6-Pin SOT-23 Package (LTC1982) U APPLICATIO S ■ ■ ■ Cellular Telephones Portable POS Terminal Handheld Battery Powered Equipment The LTC®1981/LTC1982 are low-power, self-contained N-channel MOSFET drivers. An internal voltage tripler allows gates to be driven without the use of any external components. Internal regulation circuitry allows quiescent current to drop to 10µA per driver (20µA for LTC1981) once the gates are charged. Low quiescent current and low shutdown current (under 1µA) make these parts ideal for battery and other power constrained systems. The wide input voltage range accommodates a variety of battery/input configurations. Gate drive is internally clamped to 7.5V providing protection to the external MOSFET gate. The MOSFETs can be driven in either high side or low side mode. The LTC1981 single driver version also includes a gate drive ready pin and twice the drive current capacity of the dual driver LTC1982. The LTC1981 is available in a 5-pin SOT-23. The LTC1982 is available in a 6-pin SOT-23. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATIONS Single High Side Switch Controller Dual High Side Switch Controller VCC 1.8V TO 5.0V VCC 1.8V TO 5.0V + Q1 Si3442DV 10µF Q1 1/2 Si6925DQ + 10µF Q2 1/2 Si6925DQ 5 4 6 VCC GATE VCC LTC1981 100k GATE DRIVE READY SHDN GND SHDN 1 2 3 4 LTC1982 LOAD GDR 5 GATE 1 GATE 2 SHDN 1 1 GND 2 LOAD 1 LOAD 2 SHDN 2 3 SHDN 1 1981/82 TA01 SHDN 2 1981/82 TA02 1 LTC1981/LTC1982 U W W W ABSOLUTE AXI U RATI GS (Notes 1, 2) Terminal Voltage LTC1981: VCC, GATE, SHDN, GDR ........ –0.3V to 7.5V LTC1982: VCC, GATE 1, GATE 2, SHDN 1, SHDN 2 ................... –0.3V to 7.5V Operating Temperature Range LTC1981E/LTC1982E (Note 3) ............ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C U W U PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER TOP VIEW 5 VCC GDR 1 GND 2 4 GATE SHDN 3 S5 PACKAGE 5-LEAD PLASTIC SOT-23 LTC1981ES5 S5 PART MARKING ORDER PART NUMBER TOP VIEW SHDN 1 1 6 VCC GND 2 5 GATE 1 SHDN 2 3 4 GATE 2 TJMAX = 150°C, θJA = 250°C/W LTC1982ES6 S6 PART MARKING S6 PACKAGE 6-LEAD PLASTIC SOT-23 TJMAX = 150°C, θJA = 230°C/W LTSF LTPF Consult factory for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V unless otherwise specified. CGATE 1 = CGATE 2 = CGATE = 1000pF. SYMBOL PARAMETER VCC Operating Supply Voltage ICC Supply Current GATE 1 and GATE 2 Outputs High GATE 1 or GATE 2 Outputs High GATE Output High (LTC1981) ● ● ● ISHDN SHDN Supply Current SHDN 1 and SHDN 2 Inputs Low SHDN Input Low (LTC1981) ● ● VGATE GATE Drive Output Voltage VCC = 1.8V VCC = 2.7V VCC = 3.3V VCC = 5V ● ● ● ● fOSC Charge Pump Oscillator Frequency Measured with 10k Resistor from Output to GND 600 kHz tON Turn-on Time into 1000pF From SHDN 1, SHDN 2 Going High to GATE 1, GATE 2 = VCC + 1V 110 µs From SHDN Going High to GATE = VCC +1V (LTC1981) 85 µs From SHDN 1, SHDN 2 Going Low to GATE 1, GATE 2, GATE = 100mV 12 µs tOFF Turn-off Time into 1000pF VIL SHDN Input Low Voltage VIH CIN IIN SHDN Input Leakage Current 2 CONDITIONS MIN ● VCC = 1.8V to 5.5V ● SHDN Input High Voltage VCC = 1.8V to 5.5V ● SHDN Input Capacitance (Note 4) TYP 1.8 17 10 17 4.27 6.40 6.90 6.90 4.50 6.75 7.25 7.25 MAX UNITS 5.5 V 30 20 30 µA µA µA 1 1 µA µA 4.75 7.10 7.50 7.50 V V V V 0.4 V 1.6 5 V pF ±1 µA LTC1981/LTC1982 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V unless otherwise specified. CGATE 1 = CGATE 2 = CGATE = 1000pF. (LTC1981 only) SYMBOL PARAMETER CONDITIONS MIN VOL GDR Output Voltage Low ISINK = 100µA, VCC = 1.8V ● GATE Drive Ready Trip Point GATE Voltage Rising VCC = 1.8V VCC = 2.7V VCC = 3.3V VCC = 5V ● ● ● ● 3.85 5.78 6.17 6.17 TYP MAX UNITS 0.05 0.4 V 4.05 6.08 6.5 6.5 4.25 6.38 6.82 6.82 V V V V GDR Hysteresis GATE Voltage Falling 2 % GDR Delay After GATE is Above the GDR Trip Threshold 10k Pull-Up to VCC 2 µs Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All voltage values are with respect to GND. Note 3: the LTC1982E 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 4: Guaranteed by design not subject to test. U W TYPICAL PERFOR A CE CHARACTERISTICS 100 25 VCC = 3.3V VCC = 2.7V TA = 25°C GATE DRIVE CURRENT (µA) SUPPLY CURRENT (µA) 20 LTC1981 OR BOTH CHANNELS ON LTC1982 15 10 EITHER CHANNEL ON LTC1982 5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) VCC = 5V VCC = 1.8V 10 1 TA = 25°C 0.1 0 5.5 0 1 2 3 4 5 6 GATE DRIVE VOLTAGE (V) 7 8 1982 G03 1982 G02 1982 G01 ISUPPLY ISUPPLY 300 60 TA = 25°C VCC = 3V SHDN1 TIED TO SHDN2 TA = 25°C VCC = 5V SHDN1 TIED TO SHDN2 250 SUPPLY CURRENT (µA) 50 40 30 20 10 0 GATE Drive Current (LTC1982) Supply Current vs Supply Voltage 8.0 7.5 TA = 25°C 7.0 GATE DRIVE VOLTAGE 6.5 (VGS COMMON SOURCE) 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 GATE DRIVE –VCC 2.0 (VGS SOURCE FOLLOWER) 1.5 1.0 0.5 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE, VCC (V) SUPPLY CURRENT (µA) GATE DRIVE VOLTAGE (V) GATE Drive Voltage vs Supply Voltage 200 150 100 50 0 1 SHDN LOGIC INPUT VOLTAGE (V) 2 1981/82 G04 0 0 1 SHDN LOGIC INPUT VOLTAGE (V) 2 1981/82 G05 3 LTC1981/LTC1982 U W TYPICAL PERFOR A CE CHARACTERISTICS Turn-On Time (LTC1982) 400 7.50 40 CGATE = 1000pF TA = 25°C 35 TURN-OFF TIME (µs) 300 250 VGS = 2V 200 CGATE = 1000pF TA = 25°C TIME FOR VGATE < 0.1V 150 100 30 25 20 15 10 VGS = 1V 50 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) 7.10 1 0.1 8 CGATE =1000pF TA = 25°C TIME FOR VGATE < 0.1 20 VGS = 2V 200 150 100 0 100 Turn-Off Time (LTC1981) 25 CGATE = 1000pF TA = 25°C VGS = 1V 50 80 1982 G08 TURN-OFF TIME (µs) TURN-ON TIME (µs) GATE DRIVE CURRENT (µA) 7.15 7.00 – 60 – 40 – 20 0 20 40 60 TEMPERATURE (°C) 250 7 7.20 Turn-On Time (LTC1981) VCC = 5V VCC = 3.3V 2 3 4 5 6 GATE DRIVE VOLTAGE (V) 7.25 7.05 300 10 1 7.30 1982 G07 VCC = 2.7V 0 7.35 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) GATE Drive Current (LTC1981) VCC = 1.8V 7.40 5 1982 G06 100 VCC = 3.3V 7.45 GATE DRIVE VOLTAGE (V) 350 TURN-ON TIME (µs) GATE Drive Voltage vs Temperature Turn-Off Time (LTC1982) 15 10 5 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) 1981/82 G09 1981/82 G10 1981/82 G11 U U U PIN FUNCTIONS LTC1981: GDR (Pin 1): Gate Drive Ready Active High Open Drain Output. Used to indicate when the gate drive output is greater than 90% of its final value. VCC (Pin 5): Input Supply Voltage. Range from 1.8V to 5.5V. GND (Pin 2): Ground. SHDN 1 (Pin 1): SHDN 1 Active Low Input. Used to shut down the GATE 1 charge pump and force the GATE 1 output pin to ground. SHDN (Pin 3): SHDN Active Low Input. Used to shut down the part and force the GATE output pin to ground. GATE (Pin 4): Gate Drive Output to an External High Side Switch. Fully enhanced by internal charge pump. Controlled by the SHDN input pin. Output voltage on this pin will be approximately 2.5 times VCC or 7.25V, whichever is less. 4 LTC1982: GND (Pin 2): Ground. SHDN 2 (Pin 3): SHDN 2 Active Low Input. Used to shut down the GATE 2 charge pump and force the GATE 2 output pin to ground. LTC1981/LTC1982 U U U PIN FUNCTIONS GATE 2(Pin 4): Gate Drive Output to an External High Side Switch. Fully enhanced by internal charge pump. Controlled by the SHDN 2 input pin. Output voltage on this pin will be approximately 2.5 times VCC or 7.25V, whichever is less. GATE 1 (Pin 5): Gate Drive Output to an External High Side Switch. Fully enhanced by internal charge pump. Controlled by the SHDN 1 input pin. Output voltage on this pin will be approximately 2.5 times VCC or 7.25V, whichever is less. VCC (Pin 6): Input Supply Voltage. Range from 1.8V to␣ 5.5V. W BLOCK DIAGRA SM LTC1981 Single High Side Switch Driver REGULATING EN CHARGE PUMP SHDN + 15k LTC1982 Dual High Side Switch Driver GATE EN REGULATING CHARGE PUMP 1 30k SHDN 1 EN REGULATING CHARGE PUMP 2 30k SHDN 2 GATE 1 GDR – VCC + – REF GATE 2 1981/82 BD02 1981/82 BD01 U OPERATIO Charge Pump To fully enhance the external N-channel switches, internal charge pumps are used to boost the output gate drive to approximately 2.5 times the supply voltage, or 7.25V, whichever is less. A feedback network is used to regulate the output gate drive. This keeps the supply current low in addition to providing a maximum output voltage limit. The reason for the maximum output voltage limit is to avoid switch gate source breakdown due to excessive gate overdrive. The gate drive outputs (GATE 1, GATE 2, or GATE) are controlled by the shutdown input pins (SHDN 1, SHDN 2 or SHDN). A logic high input on one of the shutdown input pins enables the corresponding charge pump and drives the related gate drive output pin high. A logic low input on one of the shutdown input pins disables the corresponding charge pump and drives the related gate drive output pin low. If shutdown input on the LTC1981 is low or both of the shutdown input pins on the LTC1982 are low, the part will be placed into a low current shutdown mode (<1µA). Gate Drive Ready (LTC1981 Only) The gate drive ready pin (GDR) is used to indicate when the gate drive output (GATE) is greater than 90% of its final value. This can be useful in applications that require knowledge of the state of the gate drive for initialization purposes or as fault detection should something be loading the gate drive down. 5 LTC1981/LTC1982 U W U U APPLICATIONS INFORMATION Logic-Level MOSFET Switches The LTC1981/LTC1982 are designed to operate with logiclevel N-channel MOSFET switches. Although there is some variation among manufacturers, logic-level MOSFET switches are typically rated with VGS = 4V with a maximum continuous VGS rating of ±8V. RDS (ON) and maximum VDS ratings are similar to standard MOSFETs and there is generally little price differential. When operating at supply voltages of 5V or greater, care must be taken when selecting the MOSFET. The LTC1981/LTC1982 limit the output voltage to between 6.9V and 7.5V. The VGS developed for the MOSFET may be too low to sufficiently turn on the MOSFET. MOSFETs rated at 2.5V, or less, will be better suited for applications where the supply voltages approach 5V. Powering Large Capacitive Loads Electrical subsystems in portable battery-powered equipment are typically bypassed with large filter capacitors to reduce supply transients and supply induced glitching. If not properly powered however, these capacitors may themselves become the source of supply glitching. For example, if a 100µF capacitor is powered through a switch with a slew rate of 0.1V/µs, the current during start-up is: ISTART = C(∆V/∆t) managed by the system regulator. R1 is required to eliminate the possibility of parasitic MOSFET oscillations during switch transitions. It is a good practice to isolate the gates of paralleled MOSFETs with 1k resistors to decrease the possibility of interaction between switches. VIN VCC 6 R1 1k ON/OFF Si3442DV GATE 1 1/2 LTC1982 C1 0.1µF SHDN 1 GND + CL 100µF 3.3V LOAD 1981/82 F01 Figure 1. Powering a Large Capactive Load Mixed 5V/3V Systems Because the input ESD protection diodes are referenced to the GND pin instead of the supply pin, it is possible to drive the LTC1981/LTC1982 inputs from 5V CMOS or TTL logic even though the LTC1981/LTC1982 is powered from a 3.3V supply as shown in Figure 2. Likewise, because the input threshold voltage high is never greater than 1.6V, the reverse situation is true. The LTC1981/LTC1982 can be driven with 3V CMOS or TTL even when the supply to the device is as high as 5V as shown in Figure 3. 3.3V = 10A The start up current can be substantially reduced by limiting the slew rate at the gate of an N-channel as shown in Figure 1. The gate drive output of the LTC1981/LTC1982 have an internal 30k resistor (15k LTC1981) in series with each of the output gate drive pins (see Functional Block Diagram). Therefore, it only needs an external 0.1µF capacitor (0.22µF for the LTC1981) to create enough RC delay to substantially slow the slew rate of the MOSFET gate to approximately 0.6V/ms. Since the MOSFET is operating as a source follower, the slew rate at the source is essentially the same as that at the gate, reducing the startup current to approximately 60mA which is easily + 3.3µF = (100 • 10–6)(1 • 105) Obviously, this is too much current for the regulator (or output capacitor) to supply and the output will glitch by as much as a few volts. 3.3V LT1129-3.3 VCC 5V GATE 1 Si3442DV 1/2 LTC1982 3.3V LOAD SHDN 1 GND 1981/82 F02 Figure 2. Direct Interface to 5V Logic 5V VCC 3.3V GATE 1 Si3442DV 1/2 LTC1982 SHDN 1 GND 5V LOAD 1981/82 F03 Figure 3. Direct Interface to 3.3V Logic LTC1981/LTC1982 U W U U APPLICATIONS INFORMATION Reverse Battery Protection The LTC1981/LTC1982 can be protected against reverse battery conditions by connecting a 150Ω resistor in series with the supply pin as shown in Figure 4. The resistor limits the supply current to less than 24mA with –3.6V applied. Because the LTC1981/LTC1982 draw very little current while in normal operation, the drop across the resistor is minimal. Control logic can be protected by adding 10k resistors in series with the input pins. VBAT (1.8V TO 5V) 10k 0.1µF GATE DRIVE READY 1 2 3 3V GDR GND VCC 5 150Ω LTC1981 SHDN GATE 4 Si3442DV 10k LOAD 1981/82 F04 Figure 4. Reverse Battery Protection U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23 (LTC DWG # 05-08-1633) 2.60 – 3.00 (0.102 – 0.118) 1.50 – 1.75 (0.059 – 0.069) 0.35 – 0.55 (0.014 – 0.022) 0.00 – 0.15 (0.00 – 0.006) 0.09 – 0.20 (0.004 – 0.008) (NOTE 2) 2.80 – 3.00 (0.110 – 0.118) (NOTE 3) 0.90 – 1.45 (0.035 – 0.057) 0.35 – 0.50 0.90 – 1.30 (0.014 – 0.020) (0.035 – 0.051) FIVE PLACES (NOTE 2) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ) 1.90 (0.074) REF 0.95 (0.037) REF S5 SOT-23 0599 S6 Package 6-Lead Plastic SOT-23 (LTC DWG # 05-08-1634) 2.6 – 3.0 (0.110 – 0.118) 1.50 – 1.75 (0.059 – 0.069) 0.35 – 0.55 (0.014 – 0.022) 0.00 – 0.15 (0.00 – 0.006) 0.09 – 0.20 (0.004 – 0.008) (NOTE 2) 0.90 – 1.45 (0.035 – 0.057) 0.35 – 0.50 0.90 – 1.30 (0.014 – 0.020) (0.035 – 0.051) 1.90 (0.074) SIX PLACES (NOTE 2) REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ) 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. 2.80 – 3.00 (0.110 – 0.118) (NOTE 3) 0.95 (0.037) REF S6 SOT-23 0898 7 LTC1981/LTC1982 U TYPICAL APPLICATIO Driving Both High Side and Low Side Switches VEXT (30V MAX) VCC 1.8 to 5.0V 10µF LOW SIDE LOAD SHDN 1 1 VCC SHDN 1 6 LTC1982 2 SHDN 2 3 GND GATE 1 SHDN 2 GATE 2 5 4 1k Q1 Si6954DQ 0.1µF 1k Q2 Si6954DQ 0.1µF HIGH SIDE LOAD 1981/82 • TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1153/LTC1154 Single High Side Micropower MOSFET Drivers Circuit Breaker with Auto Reset LTC1155/LTC1255 Dual High Side Micropower MOSFET Drivers Latchoff Current Limit LTC1163/LTC1165 Triple 1.8V to 6V High Side MOSFET Driver Three MOSFET Drivers in 8-Lead SO Package LTC1623 SMBus Dual High Side Switch Controller Uses External Switches, Two Three-State Address Pins LTC1710 SMBus Dual Monolithic High Side Switch Uses Internal Switches, One Three-State Address Pin 8 Linear Technology Corporation sn19812 19812fs LT/LCG 1200 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 2000