BQ24702_16 Datasheet, PDF (19/37 Pages) Texas Instruments – MULTICHEMISTRY BATTERY CHARGER CONTROLLER

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bq24702
bq24703
SLUS553E – MAY 2003 – REVISED OCTOBER 2007
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_mamplifier. The charge
current is then a function of this voltage drop and the sense resistor (R_S), refer to Figure 5.
R_S
COMP 10
VREF
+
SRSET
5
+
2 kΩ
SRP
16
SRN
15
25 kΩ
Figure 5. Battery Charge Current Input Threshold Function
UDG-00117
The battery charge current can be defined as:
IBAT
+
VSRSET
25 RS
(2)
where V_SRSET is the programming voltage on the SRSET pin. V_SRSET maximum is 2.5 V.
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:
IADPT
+
VACSET
25 RS2
(3)
Copyright © 2003–2007, Texas Instruments Incorporated
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