BQ2040SN-C408 BENCHMARQ, BQ2040SN-C408 Datasheet - Page 3

• Manufacturer Part Number: BQ2040SN-C408
• Description: BATTERY CHARGE MONITOR, SMD, 2040
• Manufacturer: BENCHMARQ

Specifications of BQ2040SN-C408

• Battery Management Function: Charger, Status Monitor
• Battery Type: Li-Ion / NiCd / NiMH
• Supply Voltage Range: 3V To 6.5V
• Battery Ic Case Style: SOIC
• No. Of Pins: 16
• Operating Temperature Range: 0°C
• Interface Type: 2-Wire, Serial

Functional Description
General Operation
The bq2040 determines battery capacity by monitoring
the amount of charge put into or removed from a re-
chargeable battery. The bq2040 measures discharge
and charge currents, estimates self-discharge, and
monitors the battery for low-battery voltage thresholds.
The charge is measured by monitoring the voltage
across a small-value series sense resistor between the
battery's negative terminal and ground. The available
battery charge is determined by monitoring this voltage
over time and correcting the measurement for the envi-
ronmental and operating conditions.
No. of Cells
10
12
2
3
4
6
8
9
For bq2040 With No D8
301K
499K
698K
499K
698K
806K
909K
909K
R5
Chart 1
Figure 1. Battery Pack Application Diagram—LED Display
604K
806K
604K
499K
806K
499K
604K
909K
R11
86.5K
100K
100K
100K
100K
100K
100K
100K
R4
BSS138
BSS138
BSS138
BSS138
2N7002
2N7002
2N7002
2N7002
Q1
V CC
ESCL
ESDA
LED1
LED2
LED3
LED4
V SS
bq2040
SMBC
SMBD
PSTAT
V OUT
DISP
REF
SR
SB
3
Figure 1 shows a typical battery pack application of the
bq2040 using the LED capacity display, the serial port,
and an external EEPROM for battery pack program-
ming information. The bq2040 must be configured and
calibrated for the battery-specific information to ensure
proper operation. Table 1 outlines the configuration in-
formation that must be programmed in the EEPROM.
An internal temperature sensor eliminates the need
for an external thermistor—reducing cost and compo-
nents. An internal, temperature-compensated time-
base eliminates the need for an external resonator,
further reducing cost and components. The entire cir-
cuit in Figure 1 can occupy less than
board space.
(Optional)
(Optional)
3
4
square inch of
2040LED.eps
bq2040