LTC1325_15 Datasheet, PDF (1/24 Pages) Linear Technology – Microprocessor-Controlled Battery Management System

LTC1325
Microprocessor-Controlled
Battery Management System
FEATURES
s _{Fast Charge Nickel-Cadmium, Nickel-Metal-Hydride,}
Lithium Ion or Lead-Acid Batteries under µP Control
s _{Flexible Current Regulation:}
– Programmable 111kHz PWM Current Regulator
with Built-In PFET Driver
– PFET Current Gating for Use with External Current
Regulator or Current Limited Transformer
s _{Discharge Mode}
s _{Measures Battery Voltage, Battery Temperature and}
Ambient Temperature with Internal 10-Bit ADC
s _{Battery Voltage, Temperature and Charge Time}
Fault Protection
s _{Built-In Voltage Regulator and Programmable}
Battery Attenuator
s _{Easy-to-Use 3- or 4-Wire Serial µP Interface}
s _{Accurate Gas Gauge Function}
s _{Wide Supply Range: VDD = 4.5V to 16V}
s _{Can Charge Batteries with Voltages Greater Than VDD}
s _{Can Charge Batteries from Charging Supplies Greater}
Than V_DD
s _{Digital Input Pins Are High Impedance in}
Shutdown Mode
U
APPLICATIONS
s _{System Integrated Battery Charger}
DESCRIPTION
The LTC^®1325 provides the core of a flexible, cost-effec-
tive solution for an integrated battery management sys-
tem. The monolithic CMOS chip controls the fast charging
of nickel-cadmium, nickel-metal-hydride, lead-acid or
lithium batteries under microprocessor control. The de-
vice features a programmable 111kHz PWM constant
current source controller with built-in FET driver, 10-bit
ADC, internal voltage regulator, discharge-before-charge
controller, programmable battery voltage attenuator and
an easy-to-use serial interface.
The chip may operate in one of five modes: power shut-
down, idle, discharge, charge or gas gauge. In power
shutdown the supply current drops to 30µA and in the idle
mode, an ADC reading may be made without any switching
noise affecting the accuracy of the measurement. In the
discharge mode, the battery is discharged by an external
transistor while the battery is being monitored by the
LTC1325 for fault conditions. The charge mode is termi-
nated by the µP while monitoring any combination of
battery voltage and temperature, ambient temperature
and charge time. The LTC1325 also monitors the battery
for fault conditions before and during charging. In the gas
gauge mode the LTC1325 allows the total charge leaving
the battery to be calculated.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION _{Battery Charger for up to 8 NiCd or NiMH Cells}
+ _C2
10µF
P1
IRF9730
MPU
(e.g. 8051)
p1.4
p1.3
p1.2
+ _CREG
4.7µF
R1
R2
R3
R4
LTC1325
1 _REG
2
D_OUT
3
D_IN
4
CS
5 _CLK
6 _LTF
7 _MCV
8 _HTF
9 _GND
V_DD ¹⁸
PGATE ¹⁷
DIS ¹⁶
V_BAT ¹⁵
T_BAT ¹⁴
T_AMB ¹³
V_IN ¹²
SENSE ¹¹
FILTER ¹⁰
R13
100Ω
C1
+ _CREG
0.1µF
22µF _{THERM 2}
C_F
1µF
R5
THERM 1
D1
1N6818
L1
62µH
R_TRK
R_DIS
BAT
N1
IRFZ34
R_SENSE
V_DD
4.5V TO 16V
LTC1325 • TA01
1