LTC1477/LTC1478
Single and Dual Protected
High Side Switches
FEATURES DESCRIPTION
n
Extremely Low R Switch: 0.07
The LTC 1477/LTC1478 protected high side switches
DS(ON)
n
No Parasitic Body Diode
provide extremely low R switching with built-in
DS(ON)
n
Built-In Short-Circuit Protection: 2A
protection against short-circuit and thermal overload con-
n
Built-In Thermal Overload Protection
ditions. A built-in charge pump generates gate drive
n
Operates from 2.7V to 5.5V
higher than the supply voltage to fully enhance the internal
n
Inrush Current Limited
NMOS switch. This switch has no parasitic body diode and
n
Ultralow Standby Current: 0.01A
therefore no current flows through the switch when it is
n
Built-In Charge Pump
turned off and the output is forced above the input supply
n
Controlled Rise and Fall Times: t = 1ms
voltage. (DMOS switches have parasitic body diodes that
R
n
Single Switch in 8-Pin SO Package
become forward biased under these conditions.)
n
Dual Switch in Narrow 16-Pin SO Package
Two levels of protection are provided by the
LTC1477/LTC1478. The first level of protection is short-
U
circuit current limit which is set at 2A. The short-circuit
APPLICATIONS
current can be reduced to as low as 0.85A by disconnect-
n
Notebook Computer Power Management
ing portions of the power device (see Applications Infor-
n
Power Supply/Load Protection
mation). The second level of protection is provided by
n
Supply/Battery Switch-Over Circuits
thermal overload protection which limits the die tempera-
n
Circuit Breaker Function
ture to approximately 130C.
nHot Swa Board Protection
The LTC1477 single is available in 8-lead SO packaging.
n
Peripheral Power Protection
The LTC1478 dual is available in 16-lead SO packaging.
, LTC and LT are registered trademarks of Linear Technology Corporation.
SI PLIFIED BLOCK DIAGRAM
V V V V
INS IN1 IN2 IN3
Switch Output Voltage
5.20
T = 25C
A
GATE CHARGE
V = V = V = V = 5V
IN1 IN2 IN3 INS
5.10
AND
***
DISCHARGE
CONTROL LOGIC
5.00
4.90
4.80
CURRENT LIMIT
CHARGE
V
EN AND THERMAL
OUT
PUMP 4.70
SHUTDOWN
4.60
0 0.5 0.75 1.00 1.25 1.50
0.25
OUTPUT CURRENT (A)
*NMOS SWITCHES WITH NO PARASITIC BODY DIODES
LTC1477/1478 TA01
LTC1477/1478 TP02
1
OUTPUT VOLTAGE (V)
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ULTC1477/LTC1478
ABSOLUTE MAXIMUM RATINGS
Supply Voltage .......................................................... 7V Operating Temperature
Enable Input Voltage...................... (7V) to (GND 0.3V) LTC1477C/LTC1478C .............................. 0C to 70C
Output Voltage (OFF) (Note 1) ....... (7V) to (GND 0.3V) Storage Temperature Range ................. 65C to 150C
Output Short-Circuit Duration .......................... Indefinite Lead Temperature (Soldering, 10 sec).................. 300C
Junction Temperature........................................... 110C
PACKAGE/ORDER INFORMATION
TOP VIEW
ORDER PART ORDER PART
NUMBER AV
1
16
AV
NUMBER
OUT OUT
TOP VIEW
AV
2
15
AV
IN IN2
LTC1478CS
LTC1477CS8
V
1
8
V
AV
3
14
AV
OUT OUT
INS IN3
V
2
7
V
AEN
4
13
GND
IN1 IN2
GND
5
12
BEN
V
3
6
V
INS IN3
BV
6
11
BV
EN GND
4 5 IN3 INS
S8 PART MARKING
BV
7
10
BV
IN2 IN1
S8 PACKAGE
BV
8 9 BV
8-LEAD PLASTIC SO
OUT OUT
T = 110C, = 120C/ W
JMAX JA 1477
S PACKAGE
16-LEAD PLASTIC SO
T = 110C, = 100C/ W
JMAX JA
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
V = V = V = V = 5V (Note 2), T = 25C, unless otherwise noted. Each channel of the LTC1478 is tested separately (Note 3).
INS IN1 IN2 IN3 A
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Supply Voltage Range 2.7 5.5 V
IN
I Supply Current Switch OFF, Enable = 0V l 0.01 10 A
VIN
Switch ON, Enable = 5V, V = 5V l 120 180 A
IN
Switch ON, Enable = 3.3V, V = 3.3V l 80 120 A
IN
R ON Resistance V = V = V = V = 5V, I = 1A 0.07 0.12
ON INS IN1 IN2 IN3 OUT
V = V = V = V = 3.3V, I = 1A 0.08 0.12
INS IN1 IN2 IN3 OUT
V = V = 5V, V = V = NC, I = 0.5A 0.12 0.20
INS IN1 IN2 IN3 OUT
V = V = 3.3V, V = V = NC, I = 0.5A 0.13 0.20
INS IN1 IN2 IN3 OUT
I Output Leakage Current OFF Switch OFF, Enable = 0V l 20 A
LKG
I Short-Circuit Current Limit V = V = V = V = 5V, V = 0V, (Note 4) 1.60 2.00 2.40 A
SC INS IN1 IN2 IN3 OUT
V = V = 5V, V = V = NC, V = 0V, (Note 4) 0.68 0.85 1.02 A
INS IN1 IN2 IN3 OUT
V Enable Input High Voltage 3.0V V 5.5V l 2.0 V
ENH INS
V Enable Input Low Voltage 3.0V V 5.5V l 0.8 V
ENL INS
I Enable Input Current 0V V 5.5V l 1 A
EN EN
t Delay and Rise Time R = 100, C = 1F, to 90% of Final Value 0.50 1.00 2.00 ms
D+R OUT OUT
The l denotes specifications which apply over the full operating increase the ON resistance of the switch. The LTC1478 GND pins must be
temperature range. connected together. (See Pin Functions and Block Diagram for more detail.)
Note 1: The V pins must be connected together. Note 3: Other channel turned OFF, i.e. AEN and BEN = 0V.
OUT
Note 2: The V and V pins must be connected together. The V and Note 4: The output is protected with fold-back current limit which reduces
INS IN1 IN2
V pins are typically connected to V and V pins but can be the short-circuit (0V) currents below peak permissible current levels at
IN3 INS IN1
selectively disconnected to reduce the short-circuit current limit and higher output voltages. (See Typical Performance Characteristics for
further detail on output current versus output voltage).
2
U W U
W
U WW