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LTC1981/LTC1982 Single and Dual Micropower High Side Switch Controllers in SOT-23
FEATURES
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DESCRIPTIO
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No External Components Required Internal Voltage Triplers Produce High Side Gate Drive for Logic Level FETs Ultralow Power: 10A Per Driver ON Current (LTC1982) 20A ON Current (LTC1981) <1A 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)
The LTC(R)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 10A per driver (20A for LTC1981) once the gates are charged. Low quiescent current and low shutdown current (under 1A) 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.
APPLICATIO S
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Cellular Telephones Portable POS Terminal Handheld Battery Powered Equipment
TYPICAL APPLICATIONS
Single High Side Switch Controller
VCC 1.8V TO 5.0V
Dual High Side Switch Controller
VCC 1.8V TO 5.0V
+
10F
Q1 Si3442DV
+
10F 6 VCC 5 LTC1982 SHDN 1 1 SHDN 1 GND 2 SHDN 2 3 4
5 VCC 100k GDR GATE DRIVE READY SHDN 1 LTC1981 GND 2
4 GATE LOAD SHDN 3
1981/82 TA01
SHDN 2
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Q1 1/2 Si6925DQ Q2 1/2 Si6925DQ GATE 1 GATE 2 LOAD 1 LOAD 2
1981/82 TA02
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LTC1981/LTC1982
ABSOLUTE
AXI U RATI GS
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW GDR 1 GND 2 SHDN 3 4 GATE 5 VCC
ORDER PART NUMBER LTC1981ES5 S5 PART MARKING LTSF
SHDN 1 1 GND 2 SHDN 2 3
S5 PACKAGE 5-LEAD PLASTIC SOT-23
TJMAX = 150C, JA = 250C/W
Consult factory for parts specified with wider operating temperature ranges.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V unless otherwise specified. CGATE 1 = CGATE 2 = CGATE = 1000pF.
SYMBOL VCC ICC PARAMETER Operating Supply Voltage Supply Current GATE 1 and GATE 2 Outputs High GATE 1 or GATE 2 Outputs High GATE Output High (LTC1981) SHDN 1 and SHDN 2 Inputs Low SHDN Input Low (LTC1981) VCC = 1.8V VCC = 2.7V VCC = 3.3V VCC = 5V Measured with 10k Resistor from Output to GND From SHDN 1, SHDN 2 Going High to GATE 1, GATE 2 = VCC + 1V From SHDN Going High to GATE = VCC +1V (LTC1981) tOFF VIL VIH CIN IIN Turn-off Time into 1000pF SHDN Input Low Voltage SHDN Input High Voltage SHDN Input Capacitance SHDN Input Leakage Current From SHDN 1, SHDN 2 Going Low to GATE 1, GATE 2, GATE = 100mV VCC = 1.8V to 5.5V VCC = 1.8V to 5.5V (Note 4)
q q
ELECTRICAL CHARACTERISTICS
CONDITIONS
ISHDN VGATE
SHDN Supply Current GATE Drive Output Voltage
fOSC tON
Charge Pump Oscillator Frequency Turn-on Time into 1000pF
2
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(Notes 1, 2)
Operating Temperature Range LTC1981E/LTC1982E (Note 3) ............ - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
TOP VIEW 6 VCC 5 GATE 1 4 GATE 2
ORDER PART NUMBER LTC1982ES6 S6 PART MARKING LTPF
S6 PACKAGE 6-LEAD PLASTIC SOT-23 TJMAX = 150C, JA = 230C/W
MIN
q q q q q q q q q q
TYP 17 10 17
MAX 5.5 30 20 30 1 1
UNITS V A A A A A V V V V kHz s s s V
1.8
4.27 6.40 6.90 6.90
4.50 6.75 7.25 7.25 600 110 85 12
4.75 7.10 7.50 7.50
0.4 1.6 5 1
V pF A
LTC1981/LTC1982
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V unless otherwise specified. CGATE 1 = CGATE 2 = CGATE = 1000pF. (LTC1981 only)
SYMBOL VOL PARAMETER GDR Output Voltage Low GATE Drive Ready Trip Point CONDITIONS ISINK = 100A, VCC = 1.8V GATE Voltage Rising VCC = 1.8V VCC = 2.7V VCC = 3.3V VCC = 5V GATE Voltage Falling After GATE is Above the GDR Trip Threshold 10k Pull-Up to VCC
q q q q q
ELECTRICAL CHARACTERISTICS
MIN
TYP 0.05
MAX 0.4 4.25 6.38 6.82 6.82
UNITS V V V V V % s
3.85 5.78 6.17 6.17
4.05 6.08 6.5 6.5 2 2
GDR Hysteresis GDR Delay
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 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 4: Guaranteed by design not subject to test.
TYPICAL PERFOR A CE CHARACTERISTICS
GATE Drive Voltage vs Supply Voltage
8.0 7.5 TA = 25C 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)
GATE DRIVE CURRENT (A)
GATE DRIVE VOLTAGE (V)
SUPPLY CURRENT (A)
ISUPPLY
60 50
SUPPLY CURRENT (A)
SUPPLY CURRENT (A)
TA = 25C VCC = 3V SHDN1 TIED TO SHDN2
40 30 20 10 0
0
1 SHDN LOGIC INPUT VOLTAGE (V)
UW
1982 G01
Supply Current vs Supply Voltage
25 TA = 25C 20 LTC1981 OR BOTH CHANNELS ON LTC1982 EITHER CHANNEL ON LTC1982 100
GATE Drive Current (LTC1982)
VCC = 3.3V VCC = 2.7V VCC = 1.8V 10 VCC = 5V
15
10
1
5
0
5.5
0.1 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
1982 G02
TA = 25C 0 1 2 3 4 5 6 GATE DRIVE VOLTAGE (V) 7 8
1982 G03
ISUPPLY
300 250 200 150 100 50 0 TA = 25C VCC = 5V SHDN1 TIED TO SHDN2
2
0
1 SHDN LOGIC INPUT VOLTAGE (V)
2
1981/82 G04
1981/82 G05
3
LTC1981/LTC1982 TYPICAL PERFOR A CE CHARACTERISTICS
Turn-On Time (LTC1982)
400 350
TURN-ON TIME (s)
CGATE = 1000pF TA = 25C
TURN-OFF TIME (s)
300 250 200 150 100 50 VGS = 1V VGS = 2V
30 25 20 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)
1982 G07
GATE DRIVE VOLTAGE (V)
0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V)
1982 G06
GATE Drive Current (LTC1981)
100 VCC = 2.7V VCC = 1.8V 10 VCC = 5V VCC = 3.3V
GATE DRIVE CURRENT (A)
200 150 100 50 VGS = 1V
TURN-OFF TIME (s)
TURN-ON TIME (s)
1
0.1 0 1 2 3 4 5 6 GATE DRIVE VOLTAGE (V) 7 8
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. GND (Pin 2): 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. VCC (Pin 5): Input Supply Voltage. Range from 1.8V to 5.5V. LTC1982: 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. 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.
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UW
1981/82 G09
Turn-Off Time (LTC1982)
40 35 CGATE = 1000pF TA = 25C TIME FOR VGATE < 0.1V 7.50 7.45 7.40 7.35 7.30 7.25 7.20 7.15 7.10 7.05
GATE Drive Voltage vs Temperature
VCC = 3.3V
7.00 - 60 - 40 - 20 0 20 40 60 TEMPERATURE (C)
80
100
1982 G08
Turn-On Time (LTC1981)
300 250 VGS = 2V CGATE = 1000pF TA = 25C 25
Turn-Off Time (LTC1981)
CGATE =1000pF TA = 25C TIME FOR VGATE < 0.1
20
15
10
5
0
0 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 G10
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 G11
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LTC1981/LTC1982
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.
BLOCK DIAGRA SM
LTC1981 Single High Side Switch Driver
SHDN REGULATING EN CHARGE PUMP 15k GATE
+ VCC - + - REF
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
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LTC1982 Dual High Side Switch Driver
SHDN 1 EN REGULATING CHARGE PUMP 1 30k GATE 1
GDR
SHDN 2
EN
REGULATING CHARGE PUMP 2
30k GATE 2
1981/82 BD02
1981/82 BD01
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 (<1A). 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.
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LTC1981/LTC1982
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 100F capacitor is powered through a switch with a slew rate of 0.1V/s, the current during start-up is: ISTART = C(V/t) = (100 * 10-6)(1 * 105) = 10A 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. 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 0.1F capacitor (0.22F 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
5V
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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 LT1129-3.3 3.3F VCC R1 1k GATE 1 C1 0.1F 3.3V
+
Si3442DV
1/2 LTC1982 ON/OFF SHDN 1 GND
+
CL 100F
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
VCC
GATE 1
Si3442DV
1/2 LTC1982 SHDN 1 GND 3.3V LOAD
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
APPLICATIONS INFORMATION
Reverse Battery Protection The LTC1981/LTC1982 can be protected against reverse battery conditions by connecting a 150 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.
10k 0.1F VBAT (1.8V TO 5V)
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23
2.60 - 3.00 (0.102 - 0.118) 1.50 - 1.75 (0.059 - 0.069)
0.00 - 0.15 (0.00 - 0.006)
0.35 - 0.55 (0.014 - 0.022)
0.09 - 0.20 (0.004 - 0.008) (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)
2.6 - 3.0 (0.110 - 0.118) 1.50 - 1.75 (0.059 - 0.069)
0.00 - 0.15 (0.00 - 0.006)
0.35 - 0.55 (0.014 - 0.022)
0.09 - 0.20 (0.004 - 0.008) (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)
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.
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GATE DRIVE READY
1 2 3
GDR GND SHDN LTC1981
VCC
5
150
3V 10k
GATE
4
Si3442DV
LOAD
1981/82 F04
Figure 4. Reverse Battery Protection
(LTC DWG # 05-08-1633)
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)
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)
2.80 - 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) 1.90 (0.074) SIX PLACES (NOTE 2) REF
0.95 (0.037) REF
S6 SOT-23 0898
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LTC1981/LTC1982
TYPICAL APPLICATIO U
Driving Both High Side and Low Side Switches
VCC 1.8 to 5.0V VEXT (30V MAX) 10F LOW SIDE LOAD SHDN 1 1 SHDN 1 LTC1982 2 GND GATE 1 5 VCC 6 1k 0.1F 1k 0.1F HIGH SIDE LOAD
1981/82 * TA03
Q1 Si6954DQ
SHDN 2
3
SHDN 2
GATE 2
4
Q2 Si6954DQ
RELATED PARTS
PART NUMBER LTC1153/LTC1154 LTC1155/LTC1255 LTC1163/LTC1165 LTC1623 LTC1710 DESCRIPTION Single High Side Micropower MOSFET Drivers Dual High Side Micropower MOSFET Drivers Triple 1.8V to 6V High Side MOSFET Driver SMBus Dual High Side Switch Controller SMBus Dual Monolithic High Side Switch COMMENTS Circuit Breaker with Auto Reset Latchoff Current Limit Three MOSFET Drivers in 8-Lead SO Package Uses External Switches, Two Three-State Address Pins Uses Internal Switches, One Three-State Address Pin
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
sn19812 19812fs LT/LCG 1200 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 2000

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