ltc4054l Linear Technology Corporation, ltc4054l Datasheet - Page 14

• Manufacturer Part Number: ltc4054l
• Description: 150ma Standalone Linear Li-ion Battery Charger In Thinsot
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
LTC4054L-4.2
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity
voltage on V
enough, a series blocking diode can be used. In other
cases, where the voltage drop must be kept low a P-channel
MOSFET can be used (as shown in Figure 4).
14
Figure 4. Low Loss Input Reverse Polarity Protection
CC
V
IN
is desired. If the supply voltage is high
DIODE OF FET
DRAIN-BULK
U
U
V
CC
LTC4054L
W
4054L42 F04
U
USB and Wall Adapter Power
The LTC4054L allows charging from both a wall adapter
and a USB port. Figure 5 shows an example of how to
combine wall adapter and USB power inputs. A P-channel
MOSFET, MP1, is used to prevent back conducting into the
USB port when a wall adapter is present and a Schottky
diode, D1, is used to prevent USB power loss through the
1k pull-down resistor.
ADAPTER
5V WALL
POWER
Figure 5. Combining Wall Adapter and USB Power
USB
MP1
1k
D1
4
V
LTC4054L-4.2
CC
PROG
BAT
1.5k
3
5
100mA
+
4054l42 F05
Li-Ion
BATTERY
SYSTEM
LOAD
4054l42f