LTC1732EMS-4#TRPBF Linear Technology, LTC1732EMS-4#TRPBF Datasheet - Page 10

• Manufacturer Part Number: LTC1732EMS-4#TRPBF
• Description: IC CTRLR BATT CHRG LI-ION 10MSOP
• Manufacturer: Linear Technology
• Type: Charge Controllerr

Specifications of LTC1732EMS-4#TRPBF

• Function: Charge Management
• Battery Type: Li-Ion, NiCd, NiMH
• Voltage - Supply: 4.5 V ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
• Output Current: 500mA
• Output Voltage: 4.1V
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (max): 12V
• Operating Temp Range: -40C to 85C
• Package Type: MSOP
• Mounting: Surface Mount
• Pin Count: 10
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC1732-4/LTC1732-4.2
APPLICATIONS
Gate Drive
Typically the LTC1732 controls an external P-channel
MOSFET to supply current to the battery. An external PNP
transistor can also be used as the pass transistor instead
of the P-channel MOSFET. Due to the low transconductance
of the current amplifier (CA), a high gain Darlington PNP
transistor is required to avoid excessive charge current
error. The transconductance of the current amplifier is
around 0.6 A/mV. For every 1 A of base current, a 1.6mV
of gain error shows up at the inputs of CA. With R
19.6k (100mV across R
error in charge current.
Constant-Current Only Mode
The LTC1732 can be used as a programmable current
source by connecting the TIMER pin to V
particularly useful for charging NiMH or NiCd batteries. In
the constant-current only mode, the timer and voltage
10
TYPICAL APPLICATIO S
U
SENSE
INFORMATION
U
). This represents a 1.6%
C
TIMER
0.1 F
R1
1k
U
W
R2
1k
Li-Ion Linear Charger Using a PNP Transistor
10
3
4
CHRG
ACPR
TIMER
SEL
LTC1732-4
CC
2
V
U
CC
. This is
8
SENSE
PROG
GND
PROG
DRV
BAT
5
9
7
1
6
=
R
19.6k
PROG
C1
1nF
amplifier are both disabled. An external termination method
is required to properly terminate the charging by floating
the PROG pin.
Stability
The charger is stable without any compensation when a
P-channel MOSFET is used as the pass transistor and
the battery is present. A 10 F tantalum capacitor is
recommended at the BAT pin to keep the ripple voltage
low when the battery is disconnected. A ceramic output
capacitor may also be used, but because of the very low
ESR and high Q characteristics of multilayer ceramic
capacitors, it may be necessary to add a 1 resistor in
series with the ceramic capacitor to improve voltage
mode stability.
If a PNP transistor is used for the pass transistor, a 1000pF
capacitor is required from the DRV pin to V
stablize the voltage loop a 10 F tantalum capacitor at the
BAT pin is also recommended when a battery is not
present.
Q1
2N5087
R3
10k
V
IN
= 6V
Q2
ZTX749
R
0.2
I
SENSE
MBRM120T3
BAT
C2
10 F
= 500mA
+
1732 TA02
C3
1 F
4.1V
Li-Ion
CELL
CC
. To help