LTC1477CS8 Linear Technology, LTC1477CS8 Datasheet - Page 6

• Manufacturer Part Number: LTC1477CS8
• Description: IC HI-SIDE SWITCH PROT SNGL8SOIC
• Manufacturer: Linear Technology
• Type: High Sider

Specifications of LTC1477CS8

• Input Type: Non-Inverting
• Number Of Outputs: 1
• On-state Resistance: 70 mOhm
• Current - Peak Output: 2A
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output / Channel: -

APPLICATIONS
LTC1477/LTC1478
ing of the switch parameters to the expected load current
and system current limit requirements.
A couple of examples are helpful:
1. If a nominal load of 1A was controlled by the switch
2. If a nominal load of 0.5A was controlled by the switch
Supply Bypassing
For best results, bypass the supply input pins with a single
1.0 F capacitor as close as possible to the LTC1477.
Sometimes, much larger capacitors are already available
at the output of the power supply. In this case, it is still
good practice to use a 0.1 F capacitor as close as possible
TYPICAL APPLICATIONS
6
2.7V TO 5.5V
2.7V TO 5.5V
configured to current limit at 2A (all V
together), the R
drop across the switch would be 70mV. The power
dissipated by the switch would only be 70mW.
configured to current limit at 0.85A (V
disconnected), the R
But the voltage drop would remain at 70mV and the
switch power dissipation would drop to 35mW.
0.1 F
0.1 F
ON/OFF
ON/OFF
DS(ON)
0.85A Protected Switch
U
2A Protected Switch
V
V
V
EN
V
V
V
EN
DS(ON)
OUT
IN1
INS
OUT
IN1
INS
INFORMATION
would be 0.07 and the voltage
U
LTC1477
LTC1477
would increase to 0.14 .
U
V
GND
V
V
V
GND
OUT
V
V
W
IN2
IN3
OUT
IN2
IN3
IN
pins connected
NC
NC
IN2
LTC1477/1478 • TA03
+
+
LTC1477/1478 • TA05
U
and V
1 F
1 F
I
SC
I
SC
= 0.85A
= 2A
IN3
to the LTC1477, especially if the power supply output
capacitor is more than 2 inches away on the printed circuit
board.
Output Capacitor
The output pin is designed to ramp on slowly, typically
1ms rise time. Therefore, very large output capacitors can
be driven without producing voltage spikes on the supply
pins (see graphs in Typical Performance Characteristics).
The output pin should have a 1 F capacitor for noise
reduction and smoothing.
Supply and Input Sequencing
The LTC1477 is designed to operate with continuous
power (quiescent current drops to < 1 A when disabled).
If the power must be turned off, for example to enter a
system “sleep” mode, the enable input must be turned off
100 s before the input supply is turned off to ensure that
the gate of the NMOS switch is completely discharged
before power is removed. However, the input control and
power can be applied simultaneously during power up.
2.7V TO 5.5V
2.7V TO 5.5V
2A Protected Switch Driving a Large Capacitive Load
0.1 F
0.1 F
ON/OFF
ON/OFF
1.5A Protected Switch
V
V
V
EN
OUT
IN1
INS
V
V
V
EN
OUT
IN1
INS
LTC1477
LTC1477
V
GND
V
V
OUT
IN2
IN3
V
GND
V
V
OUT
IN2
IN3
NC
+
LTC1477/1478 • TA04
+
LTC1477/1478 • TA06
1 F
I
SC
C
100 F
V
LOAD
= 1.5A
OUT