SC802IMLTRT Semtech, SC802IMLTRT Datasheet - Page 11

• Manufacturer Part Number: SC802IMLTRT
• Description: IC, BATTERY CHARGER, 1A, MLPQ-16
• Manufacturer: Semtech

Specifications of SC802IMLTRT

• Battery Type: Li-Ion, Li-Polymer
• Input Voltage: 14V
• Battery Charge Voltage: 4.2V
• Charge Current Max: 1A
• Battery Ic Case Style: MLPQ
• No. Of Pins: 16
• No. Of Series Cells: 1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Applications Information (continued)
page 1, an increasing battery temperature produces a
decreasing NTC pin voltage, designated V
When V
below the Charger Enable threshold) or less than the low
(hot) threshold (but above the Disable threshold), the
charge cycle is suspended, turning off the output. This
suspends but does not reset the charge timer, and indi-
cates a charging fault by blinking the CHRGB status indi-
cator. Hysteresis is provided for both high and low NTC
thresholds to avoid chatter at the NTC temperature fault
thresholds. When V
to-Charge range, the charge timer resumes, CHRGB is
asserted (pulled low), the charging output is enabled, and
the charge cycle continues. The timer will expire when
the output on-time exceeds the timer setting, regardless
of how long it has been disabled due to an NTC fault.
All EN_NTC input thresholds are proportional to the VCC
pin voltage (V
circuit is used, the external EN_NTC pin voltage is also
proportional to V
tance. This ensures that all EN_NTC thresholds are insensi-
tive to V
given by the parameters RT
between
battery temperature is safe to charge, and enables charg-
ing. See the following table.
When V
disabled. This allows the system controller to asynchro-
nously disable or reset the device by pulling EN_NTC to
ground, using for example an n-channel FET. When dis-
abled, the charger is turned off , the charge timer is reset,
Ratiometric
Thresholds
V
EN_NTC
EN_NTC
EN_NTC
VCC
EN_NTC Pin Ratiometric Thresholds
RT
. The ratiometric hot and cold thresholds are
is greater than the high (cold) threshold (but
NTC_HF
< 1V approximately, the SC802/A charger is
VCC
RT
RT
RT
RT
). When the recommended external NTC
% of V
NTC_EN
NTC_CR
NTC_HF
×V
NTC_DIS
VCC
EN_NTC
, varying with the thermistor resis-
VCC
= 90%
= 75%
= 30%
= 1V
VCC
and
returns to the Temperature-OK-
RT
NTC_HF
NTC_CR
and RT
×V
NTC Temperature-
Charger Disable
Charger Enable
NTC Cold Fault
OK-to-Charge
NTC Hot Fault
VCC
Range
EN_NTC
indicates the
NTC_CR
© 2008 Semtech Corporation
.
. V
EN_NTC
and CHRGB is turned off (high). The behavior of CPB
diff ers between the SC802 and SC802A when the device
is disabled. See the Status Indicators section.
Charger Enable is selected when the battery (along with
the thermistor) is removed, determined by the NTC pin
exceeding RT
voltage. Charger Enable behaves identically to NTC safe-
to-charge. Charger Enable also provides a convenient
means to operate the SC802/A in applications without a
battery thermistor, without requiring a passive resistor
network to obtain 50% of V
to VCC, or via a pullup resistor if it will be necessary to
disable the charger by pulling EN_NTC to ground.
The response of the SC802/A to an EN_NTC pin voltage
above the NTC Cold Fault threshold (but below RT
or below the low NTC Hot Fault threshold (but above
VT
be confi gured with the battery pack thermistor between
EN_NTC and VCC, and a fi xed resistor between EN_NTC
and ground, reversing the designation of the hot and cold
thresholds. This confi guration may be used to disable the
charger when the battery pack is removed.
For detailed design guidance for ratiometric NTC inter-
faces, including thermistor selection guidelines, see the
Semtech Application Note AN–PM–0801, NTC Thermistor
Network Design for Ratiometric Thresholds.
Status Indicators
There are two status indicator outputs on the SC802/A —
CHRGB (Charge) and CPB (Charger Present). These
outputs are open drain n-channel MOSFET drivers suit-
able for driving LEDs directly. The following table defi nes
each output state.
NTC_DIS
) is the same. Therefore the EN_NTC network can
NTC_EN
× V
VCC
, nominally 90% of the VCC pin
VCC
. Connect EN_NTC directly
SC802/SC802A
NTC_EN
11
)