ISL6297CRZ-T Intersil, ISL6297CRZ-T Datasheet - Page 12

• Manufacturer Part Number: ISL6297CRZ-T
• Description: IC CHARGER LI-ION POLYMER 16-QFN
• Manufacturer: Intersil

Specifications of ISL6297CRZ-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
• Other names: ISL6297CRZ-TTR

unless the input power is recycled, or a fault occurs. During
a recharge operation, the indicator remains green.
When a temperature fault happens, both the RED and the
GRN pins turn on to indicate a yellow color. This fault is
cleared automatically when the temperature again returns to
the normal region. If the FAULT is non-temperature related,
the yellow indicator flashes. This type of fault is latched and
can only be reset by toggling the EN pin or cycling the input
power. Table 2 summarizes the LED indications.
Because the LED outputs provide a constant 10mA current
sink, no external resistors are necessary.
VSEN Pin
When the charger is providing a large current to the cell,
there can be significant voltage drop in the PCB trace
between the charger output and the battery positive terminal.
To minimize this effect, the VSEN pin input provides a low
current monitoring path. This provides a more accurate
reading of the battery voltage. Figure 7 shows the internal
voltage feedback circuit.
Plug In Indication
Charging
Full Charge (EOC) or recharging
Short circuit Error or trickle charge
TIMEOUT error
Over/Under Ambient Temperature
Idle state
FIGURE 7. THE INTERNAL VOLTAGE FEEDBACK CIRCUIT
TABLE 2. LED INDICATION SUMMARY
STATUS
ENABLE
Enable
VA
+
-
V
REF
Q1
R3
R2
12
RED GRN
VSEN
BAT
VSEN
BAT
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
L
L
L
L
L
Red (500ms)
Green (500ms)
Yellow (500ms)
Off (500ms)
Red
Green
Yellow (Flashing
1Hz rate)
Yellow
Off or Battery (+)
terminal not
connected
INDICATION
ISL6297
THERMAGUARD™ Charge Current Thermal
Foldback
Over-heating is always a concern in a linear charger or in the
linear region for a dual mode charger. The charge current
thermal foldback function in the ISL6297 frees users from
the over-heating concern.
Figure 8 shows the current signals at the summing node of
the current error amplifier CA in the “Block Diagram” on
page 5. I
Temperature Monitoring block. The I
charge current until the internal temperature reaches
approximately +100°C; then I
When I
current I
current, the charge current is 100,000 times that of the
sensed current and reduces at a rate of 100mA/°C. For a
charger with the constant charge current set at 1A, the
charge current is reduced to zero when the internal
temperature rises to +110°C. The actual charge current
settles between +100°C to +110°C.
Usually the charge current should not drop below I
because of the thermal foldback. If, in some extreme case
this does happen, the charger does not indicate end-of-
charge unless the battery voltage is already above the
recharge threshold.
Ambient Temperature Sensing
The TEMP pin sets the allowable ambient temperature
range for charging the battery. Typically, an NTC (negative
temperature coefficient) resistor is mounted on the printed
circuit board (PCB) to monitor the ambient temperature. Due
to the self-heating of the PCB during charging, the ISL6297
provides the DT pin to set a higher temperature threshold
during the charge operation.
Figure 9 shows the internal circuit for the ambient
temperature sensing function. Two comparators form a
window comparator whose high-threshold is V
threshold is V
Electrical Specifications. The two MOSFETs (Q1 and Q2)
create a hysteresis for each comparator, respectively. The
DT pin is shorted to GND via the internal Q3 MOSFET when
the charger is not charging, resulting in the equivalent circuit
shown in Figure 10A. The ON-resistance of Q3 is typically
FIGURE 8. CURRENT SIGNALS AT THE AMPLIFIER CA INPUT
T
SEN
R
rises, the current control loop forces the sensed
is the reference. I
to reduce at the same rate. As a mirrored
TMAX
. These two thresholds are given in the
T
T
is the current from the
rises at a rate of 1μA/°C.
100
O
T
C
has no impact on the
I
R
TEMPERATURE
Temperature
I
SEN
TMIN
I
T
MIN
July 30, 2007
and low-
FN9215.2