ISL6292-1CR5Z-T Intersil, ISL6292-1CR5Z-T Datasheet - Page 11

• Manufacturer Part Number: ISL6292-1CR5Z-T
• Description: IC BATT CHRGR LI-ION 4.1V 16-QFN
• Manufacturer: Intersil

Specifications of ISL6292-1CR5Z-T

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 4.3 V ~ 6.5 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-VQFN Exposed Pad, 16-HVQFN, 16-SQFN, 16-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When using a current-limited adapter, the thermal situation
in the ISL6292 is totally different. Figure 18 shows the typical
charge curves when a current-limited adapter is employed.
The operation requires the I
than the limited current I
Figure 18. The key difference of the charger operating under
such conditions occurs during the CC mode.
The Block Diagram (Figure 16) aids in understanding the
operation. The current loop consists of the current amplifier
CA and the sense MOSFET Q
is programmed by the IREF pin. The current amplifier CA
regulates the gate of the sense MOSFET Q
sensed current I
main MOSFET Q
current mirror with a ratio of 100,000:1, that is, the output
charge current is 100,000 times I
current loop tries to increase the charge current by
enhancing the sense MOSFET Q
current matches the reference current. On the other hand,
the adapter current is limited, the actual output current will
never meet what is required by the current reference. As a
result, the current error amplifier CA keeps enhancing the
Q
fully turned on. Therefore, the main MOSFET becomes a
power switch instead of a linear regulation device. The
power dissipation in the CC mode becomes Equation 2:
where r
fully turned on. This power is typically much less than the
peak power in the traditional linear mode.
The worst power dissipation when using a current-limited
adapter typically occurs at the beginning of the CV mode, as
shown in Figure 18. Equation 1 applies during the CV mode.
When using a very small PCB whose thermal impedance is
relatively large, it is possible that the internal temperature
can still reach the thermal foldback threshold. In that case,
the IC is thermally protected by lowering the charge current,
as shown with the dotted lines in the charge current and
power curves. Appropriate design of the adapter can further
reduce the peak power dissipation of the ISL6292.
See“Applications Information” on page 11 for more
information.
Figure 19 illustrates the typical signal waveforms for the
linear charger from the power-up to a recharge cycle. More
detailed Applications Information is given in the following.
Applications Information
Power on Reset (POR)
The ISL6292 resets itself as the input voltage rises above
the POR rising threshold. The V2P8 pin outputs a 2.8V
voltage, the internal oscillator starts to oscillate, the internal
timer is reset, and the charger begins to charge the battery.
P
SEN
CH
=
as well as the main MOSFET Q
DS(ON)
r
DS ON
(
)
is the resistance when the main MOSFET is
⋅
SEN
MAIN
I
CHARGE
matches the reference current I
and the sense MOSFET Q
LIM
2
REF
of the adapter, as shown in
11
SEN
to be programmed higher
R
SEN
. The current reference I
. In the CC mode, the
, so that the sensed
MAIN
, until they are
SEN
so that the
SEN
R
(EQ. 2)
form a
. The
R
ISL6292
The two indication pins, STATUS and FAULT, indicate a
LOW and a HIGH logic signal respectively. Figure 19
illustrates the start-up of the charger between t
The ISL6292 has a typical rising POR threshold of 3.4V and
a falling POR threshold of 2.4V. The 2.4V falling threshold
guarantees charger operation with a current-limited adapter
to minimize the thermal dissipation.
Charge Cycle
A charge cycle consists of three charge modes: trickle mode,
constant current (CC) mode, and constant voltage (CV) mode.
The charge cycle always starts with the trickle mode until the
battery voltage stays above V
consecutive cycles of the internal oscillator. If the battery
voltage drops below V
counter is reset and the charger stays in the trickle mode. The
charger moves to the CC mode after verifying the battery
voltage. As the battery-pack terminal voltage rises to the final
charge voltage V
voltage is regulated at the constant V
the charge current is expected to decline. After the charge
current drops below I
package and programmed to 1/10 of I
package; see “End-of-Charge (EOC) Current” on page 13 for
more detail), the ISL6292 indicates the end-of-charge (EOC)
with the STATUS pin. The charging actually does not
terminate until the internal timer completes its length of
TIMEOUT in order to bring the battery to its full capacity.
Signals in a charge cycle are illustrated in Figure 19 between
points t
STATUS
I
CHARGE
FAULT
VBAT
V2P8
VIN
2
to t
t
0
FIGURE 19. OPERATION WAVEFORMS
5
.
t
1
t
CH
2
t
3
, the CV mode begins. The terminal
POR Threshold
Charge Cycle
MIN
MIN
1/8 TIMEOUT
15 Cycles to
(programmable for the 4x4 and 5x5
2.8V V
t
4
during the 15 cycles, the 15-cycle
MIN
MIN
V
RECHRG
(2.8V typical) for 15
t
5
I
MIN
CH
REF
t
in the CV mode and
6
for the 3x3
t
7
Charge Cycle
15 Cycles
0
December 17, 2007
to t
2
.
FN9105.9
t
8