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PROGRAMMING THE BATTERY CHARGE CURRENT
UDG-00117
R
S
25 kΩ
10
5
16
COMP
+
2 kΩ
15
+
SRN
SRP
V
REF
SRSET
I
BAT
+
V
SRSET
25 R
S
(2)
PROGRAMMING THE ADAPTER CURRENT
I
ADPT
+
V
ACSET
25 R
S2
(3)
bq24702
bq24703
SLUS553E – MAY 2003 – REVISED OCTOBER 2007
The battery charge current is programmed via a voltage on the SRSET pin. This voltage can be derived from a
resistor divider from the 5-V VREF or by means of an DAC. The voltage is converted to a current source that is
used to develop a voltage drop across an internal offset resistor at one input of the SR g
m
amplifier. The charge
current is then a function of this voltage drop and the sense resistor (R
S
), refer to Figure 5 .
Figure 5. Battery Charge Current Input Threshold Function
The battery charge current can be defined as:
where V
SRSET
is the programming voltage on the SRSET pin. V
SRSET
maximum is 2.5 V.
Like the battery charge current described previously, the adapter current is programmed via a voltage on the
ACSET pin. That voltage can either be from an external resistor divider from the 5-V VREF or from an external
DAC. The adapter current is defined as:
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