ISL6292BCRZ Intersil, ISL6292BCRZ Datasheet - Page 7

• Manufacturer Part Number: ISL6292BCRZ
• Description: IC CHARGER LI-ION 4.2V 4X4 16QFN
• Manufacturer: Intersil

Specifications of ISL6292BCRZ

• 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

Theory of Operation
The ISL6292B is based on the Intersil Patent-pending
dual-mode charging technology. The dual-mode technology
generates very low heat, which enables the charger to be
used in space-limited applications.
To take advantage of the low-heat feature, a current-limited
ac/dc converter is required as the power supply to the
charger. The current-limited supply has the I-V
characteristics shown in Figure 1. The supply is a dc source
before the load current reaches the limited current I
Once the current limit is reached, the supply current cannot
increase further; instead, the supply voltage falls. The
current-limited supply is equivalent to a voltage source with
an equivalent output impedance or a current source,
depending on the region it operates at, as shown in Figure 1.
The ISL6292B charges a battery with the traditional constant
current/constant voltage (CC/CV) profile. The constant
current is determined by the current limit I
during the constant-current charge mode. To ensure dual-
mode operation, the current protection level set by the IREF
pin should be higher than I
charge mode, the battery voltage is regulated at 4.2V. When
the battery voltage is below the V
Specification, the charger preconditions the battery using
trickle charge mode. The trickle-charge current is 10% of the
protection current level programmed by the IREF pin.
Figure 2 shows the typical waveforms in a charge cycle of
the dual mode operation. When the battery is below V
the charge current is 10% of I
the charge current is much less than the I
converter operates in the voltage source region. Once the
battery voltage exceeds V
on the internal P-channel power MOSFET. The ac/dc
converter operates in the current-limited region and its
voltage is pulled down to a level slightly higher than the
battery voltage. As shown in Figure 2, the charge current is
I
the 4.2V V
ac/dc supply moves out of the current-limit region and
LIM
FIGURE 1. THE I-V CHARACTERISTICS OF THE CURRENT-
and is lower than I
V
V
NL
FL
CH
, the charge current starts to decrease. The
LIMITED AC/DC CONVERTER.
V
C
r
O
NL
REF
MIN
LIM
. As the battery voltage reaches
REF
, the charger starts to fully turn
. In the constant-voltage
7
MIN
set by the IREF pin. Since
r
O
= (V
I
LIM
given in the Electrical
NL
LIM
LIM
- V
FL
, the ac/dc
)/I
of the supply
I
LIM
LIM
B
A
LIM
MIN
.
,
ISL6292B
becomes a voltage source again. When the charge current
reaches a programmable end-of-charge (EOC) level set by
the IMIN pin, the charger sends out an EOC indication. The
real termination of the charger happens at the end of a total
charge time set by the TIME pin.
The power dissipation is also shown in Figure 2. The power
dissipation in both the trickle mode and the constant-current
(CC) mode are very low. The possible peak power occurs at
the transition from the CC mode to the constant-voltage (CV)
mode. This peak power is much lower than the peak power
normally seen in a linear charger and can be further reduced
by properly designing the ac/dc converter. One simple
approach is to design the ac/dc converter output voltage just
high enough to fully charge the battery (normally lower than
5V). More information can be found in the ISL6292
datasheet available at http://www.intersil.com. To ensure the
thermal safety, the ISL6292B has an internal thermal fold-
back function that automatically reduces the charge current
if the internal temperature typically rises above 100°C.
The ISL6292B offers many other features. The trickle
current, the CC charge current, and the end-of-charge
(EOC) current are all programmable. A thermal foldback
function monitors the internal temperature and reduces the
charge current when the internal temperature rises above
100°C to prevent further temperature rise. A safety timer
sets the charge time limit for both trickle mode and fast mode
charge. When the battery voltage drops after the charge
cycle terminates, the charger automatically starts recharging
the battery to full. Two indication pins are designed to drive a
tri-color LED (a red and a green LED in the same package).
A simple thermistor circuit interface allows the user to set a
different level of ambient temperature before and after the
charger starts. All these features are described in detail in
the Application Information section.
FIGURE 2. TYPICAL CHARGE CURVES USING A CURRENT-
I
REF
V
V
I
I
V
LIM
/10
M IN
REF
P
P
CH
IN
1
2
Trickle
Mode
LIMITED ADAPTER.
Input Voltage
Current Mode
Constant
TIMEOUT
Voltage Mode
Constant
Power Dissipation
Battery Voltage
Charge Current
Inhibit
April 19, 2005
FN9139 .1