LTC1477_15 Datasheet, PDF (1/8 Pages) Linear Technology – Single and Dual Protected High Side Switches

LTC1477/LTC1478
Single and Dual Protected
High Side Switches
FEATURES
s _{Extremely Low RDS(ON) Switch: 0.07Ω}
s _{No Parasitic Body Diode}
s _{Built-In Short-Circuit Protection: 2A}
s _{Built-In Thermal Overload Protection}
s _{Operates from 2.7V to 5.5V}
s _{Inrush Current Limited}
s _{Ultralow Standby Current: 0.01µA}
s _{Built-In Charge Pump}
s _{Controlled Rise and Fall Times: tR = 1ms}
s _{Single Switch in 8-Pin SO Package}
s _{Dual Switch in Narrow 16-Pin SO Package}
U
APPLICATIONS
s _{Notebook Computer Power Management}
s _{Power Supply/Load Protection}
s _{Supply/Battery Switch-Over Circuits}
s _{Circuit Breaker Function}
s _{"Hot Swap" Board Protection}
s _{Peripheral Power Protection}
DESCRIPTION
The LTC^®1477/LTC1478 protected high side switches
provide extremely low R_DS(ON) switching with built-in
protection against short-circuit and thermal overload con-
ditions. A built-in charge pump generates gate drive
higher than the supply voltage to fully enhance the internal
NMOS switch. This switch has no parasitic body diode and
therefore no current flows through the switch when it is
turned off and the output is forced above the input supply
voltage. (DMOS switches have parasitic body diodes that
become forward biased under these conditions.)
Two levels of protection are provided by the
LTC1477/LTC1478. The first level of protection is short-
circuit current limit which is set at 2A. The short-circuit
current can be reduced to as low as 0.85A by disconnect-
ing portions of the power device (see Applications Infor-
mation). The second level of protection is provided by
thermal overload protection which limits the die tempera-
ture to approximately 130°C.
The LTC1477 single is available in 8-lead SO packaging.
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_INS
V_IN1
V_IN2
V_IN3
GATE CHARGE
AND
DISCHARGE
CONTROL LOGIC
*
*
*
EN
CHARGE
PUMP
CURRENT LIMIT
AND THERMAL
SHUTDOWN
V_OUT
*NMOS SWITCHES WITH NO PARASITIC BODY DIODES
LTC1477/1478 • TA01
Switch Output Voltage
5.20
T_A = 25°C
5.10 ^VIN1 ^{= V}IN2 ^{= V}IN3 ^{= V}INS ^{= 5V}
5.00
4.90
4.80
4.70
4.60
0
0.25 0.5 0.75 1.00 1.25 1.50
OUTPUT CURRENT (A)
LTC1477/1478 • TP02
1