SC802IMLTRT Semtech, SC802IMLTRT Datasheet - Page 9

• 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
General Operation
The SC802 and SC802A can be confi gured independently
with respect to fast-charge and termination current,
output voltage, timing, and operation with and without a
battery (LDO mode). A typical charging cycle is described
in this section. Details on alternate applications and
output programmability are covered in subsequent sec-
tions. Wherever the SC802 and SC802A descriptions are
the same, the part will be referred to as the SC802/A.
The charging cycle begins when the adapter is plugged in.
The SC802/A performs glitch fi ltering on the VCC input
and initiates a charge cycle when V
and CHRGB signals turn on the charger LED’s. If the battery
voltage is less than 2.8V, the SC802/A will charge the
output with the pre-charge current. When the battery
voltage exceeds 2.8V, the SC802/A enters fast-charge or
Constant Current (CC) regulation. When the battery
voltage reaches its fi nal value, the charger enters Constant
Voltage (CV) regulation. The CV regulation output voltage,
(V
V
the available Adjust Mode. In CV regulation the battery
accepts decreasing current until the output current (I
reaches the programmed termination current, designated
(I
When I
the CHRGB status indicator turns off, but the SC802/A
continues to hold the battery in CV regulation until the
timer cycle is completed. At this point the charger enters
the monitor state where the output remains off until V
drops by VT
is initiated.
Termination Current
When the battery reaches the CV voltage (V
transitions from a constant current source to a constant
voltage source. The current through the battery begins to
decrease while the voltage remains constant until the
current decreases below the programmed termination
current set by the ITERM pin resistance to ground. Upon
termination, the SC802/A will turn off the CHRGB status
indicator. If the timer is enabled, the output will remain in
CV regulation until the timer cycle is complete. If the timer
is disabled, then the output will turn off as soon as the
termination current level is reached. The termination
TERM
CV-LO
CV
), can be programmed to fixed values V
).
= 4.1V, or programmed to any voltage V
VOUT
< I
ReQ
TERM
, nominally 100mV, and a new charge cycle
, an event known as charge termination,
VCC
> VT
CV
UVLOR
), the charger
CV-HI
© 2008 Semtech Corporation
CV-ADJ
. The CPB
= 4.2V,
using
VOUT
VOUT
)
current is programmed according to the following
equations.
The termination current is programmable up to 67mA for
the SC802, and up to 150mA for the SC802A.
Pre-Charge
Pre-charge regulation is automatically enabled when the
battery voltage is below the pre-charge threshold, VT
nominally 2.8V. Pre-charge is required to precondition
the battery for fast-charging, and to limit the power dis-
sipation in the charger. The pre-charge current value, I
is determined by the ITERM pin resistance to ground. The
pre-charge current is programmable from 10mA to
125mA with the SC802, and up to 150mA with the
SC802A. The pre-charge current is given by the following
equations.
If the charge timer is enabled, a pre-charge timer is also
enabled. If the pre-charge time exceeds 1/4 of the pro-
grammed total charge time, the charger will turn off and
a pre-charge fault will be indicated by blinking the CHRGB
status indicator. This fault is cleared when the charger is
disabled (by grounding the EN_NTC pin), or the VCC input
voltage is cycled, or the output voltage rises above 2.8V.
Fast-Charge
Fast-charge or CC regulation is active when the battery
voltage is above VT
charge voltage of the battery. The fast-charge current
can be set to a maximum of 1.5A and is selected by the
program resistor on the IPRGM pin. The voltage on this
pin represents the current through the battery. It enables
a microprocessor via an Analog-to-Digital Converter
(ADC) to monitor battery current by sensing the voltage
I
I
I
I
PQ
PQ
TERM
TERM
R
R
1
2
ITERM
ITERM
R
R
8 .
5 .
1
1
ITERM
ITERM
5 .
5 .
88
97
88
97
PreQ
and less than V
SC802/SC802A
CV
, the fi nal fl oat
(SC802A)
(SC802A)
(SC802)
(SC802)
PreQ
PQ
,
,
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