ISL6293 Datasheet, PDF (6/8 Pages) Intersil Corporation – Li-ion/Li Polymer Battery Charger Accepting Two Power Sources

ISL6293
EN (Pin 5)
Enable logic input. Connect to LOW or leave floating to
enable the charger.
IUSB (Pin 6)
The IUSB pin programs the USB charge current. This pin is
regulated to 0.8V. The current flowing out of this pin is
mirrored to the USB charge current control reference. When
the USBP pin is connected to logic HIGH, the typical USB
charge current can be found as:
I_USB
=
45000
⋅
--^V----^R----^E----^F---
R_IUSB
=
45000
×
---⁰---^.--⁸----^V-----
R_IUSB
(
A
)
The R_IUSB has a programming range of 80kΩ to 103kΩ,
such that the USB current has a typical value ranges from
350mA to 450mA.
When the USBP pin is driven to logic LOW, the charge
current is approximately 1/5 of the above value.
USBP (Pin 7)
USB port selection logic input. When this pin is left floating or
driven to logic LOW, the USB port is regarded as a low-
power port, such that the charge current is 84mA. When this
pin is driven to logic HIGH, the USB port is considered a
high-power port, and the charge current is 450mA. The ratio
of the charge current when this pin is HIGH or LOW is fixed
at approximately 5:1.
GND (Pin 8)
System ground.
ICDL (Pin 9)
The ICDL pin has two functions. The first function is to
program the cradle charge current during the constant-
current mode. The voltage of this pin is 1.20V during the
constant-current mode of the cradle charger. The constant-
current mode current is programmed by the following
equation:
I_CDL=
-¹----^.-²----⁰---^V----
R_ICDL
⋅
r
a
t
i
o
(A)
where R_ICDL is the resistor connected to the ICDL pin (see
the Typical Application). The ratio is given by the following
table and curve.
TABLE 1. RATIO vs R_ICDL
R_ICDL (kΩ)
Ratio
1.5
1291
2.2
1216
3.0
1155
3.9
1122
4.6
1088
It is recommended that the charge current be programmed
in the range of 300mA to 1A.
1280
1250
1220
1190
1160
1130
1100
1070
1
2
3
4
5
R_ICDL (kΩ)
FIGURE 1. THE RATIO USED IN THE CHARGE CURRENT
CALCULATION vs R_ICDL
The second function of the ICDL pin is to monitor the actual
charge current. The voltage of this pin, V_ICDL, is proportional
to the actual charge current, I_CHG, in either the USB or the
cradle charger. When the cradle charger or the USB charger
is working with USBP connected to logic HIGH, the ICDL pin
voltage is given by the following equation.
V_ICDL=
1_----._--2_---0_----V_--
I_CDL
⋅
I_C
H
G
=
R_{-----I--C----D----L-----}⋅_---I_{--C----H----G---}
ratio
where the ratio has the same value given in Table 1.
The cradle charge current should be programmed equal or
higher than the USB current; otherwise, the ICDL pin voltage
will be higher than 1.20V during the constant current mode
when the USB charger is working. The charger still works
properly but the accuracy of the current monitoring voltage
degrades and saturates at approximately 2.1V.
When the USB charger is working with the USBP pin
connected to logic LOW, the ICDL pin voltage is
approximately five times of the above equation.
BAT (Pin 10)
Charger output pin. Connect this pin to the battery pack or
the battery cell. A 1µF or larger value ceramic capacitor is
recommended for decoupling. The charger relies on the
battery for stability so a battery should always be connected
to the BAT pin.
Description
The ISL6293 is designed for a single-cell Li-ion or Li-polymer
battery charging circuit that accepts both a USB port and a
desktop cradle as its power source. The charge current from
each power source is independently programmable but only
one of the two sources charges the battery. The following
describes the operation of the charger.
6
FN9180.0