ꢀ ꢁ ꢂ ꢃꢄ ꢅ ꢂꢆ ꢀ ꢁ ꢂ ꢃꢄꢅ ꢇ
SLUS553D − MAY 2003 − REVISED JULY 2005
Programming the Battery Charge Current
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 amplifier. The charge
m
current is then a function of this voltage drop and the sense resistor (R ), refer to Figure 5.
S
R
S
COMP 10
SRP
SRN
2 k
Ω
16
15
+
V
REF
SRSET
5
+
25 kΩ
UDG−00117
Figure 5. Battery Charge Current Input Threshold Function
The battery charge current can be defined as:
V
SRSET
I
+
BAT
25 R
S
(2)
where V
is the programming voltage on the SRSET pin. V
maximum is 2.5 V.
SRSET
SRSET
Programming the Adapter Current
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:
V
ACSET
I
+
ADPT
25 R
S2
(3)
20
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