LTC4100 Linear Technology, LTC4100 Datasheet - Page 6

• Manufacturer Part Number: LTC4100
• Description: Smart Battery Charger Controller
• Manufacturer: Linear Technology

PI FU CTIO S
LTC4100
TGATE (Pin 1): Drives the Top External P-MOSFET of the
Battery Charger Buck Converter.
PGND (Pin 2): High Current Ground Return for BGATE
Driver.
BGATE (Pin 3): Drives the Bottom External N-MOSFET of
the Battery Charger Buck Converter.
INFET (Pin 4): Drives the Gate of the External Input
P-MOSFET.
DCIN (Pin 5): External DC Power Source Input.
CHGEN (Pin 6): Digital Bidirectional Pin to Enable Charger
Function. This pin is connected as a wired AND bus.
SMBALERT (Pin 7): Active Low Interrupt Output to Host
(referred to as the SMBALERT# signal in the SMBus
Revision 1.1 specification). Signals host that there has
been a change of status in the charger registers and that
the host should read the LTC4100 status registers to
determine if any action on its part is required. This signal
can be connected to the optional SMBALERT# line of the
SMBus. Open drain with weak current source pull-up to
V
SDA (Pin 8): SMBus Data Signal from Main (host-con-
trolled) SMBus. External pull-up resistor is required.
SCL (Pin 9): SMBus Clock Signal from Main (host-con-
trolled) SMBus. External pull-up resistor is required.
ACP (Pin 10): This Output Indicates the Value of the DCDIV
Comparator. It can be used to indicate whether AC is
present or not.
DCDIV (Pin 11): Supply Divider Input. This is a high
impedance comparator input with a 1.2V threshold (rising
edge) and hysteresis.
GND (Pin 12): Ground for Digital and Analog Circuitry.
6
DD
The following events will cause the POWER_FAIL bit in
the ChargerStatus register to become set:
1. An external device pulling the CHGEN signal to within
0.9V to GND;
2. The AC adapter voltage is not above the battery
voltage.
U
(with Schottky to allow it to be pulled to 5V externally).
U
U
I
this pin and GND. The value of the external resistor
programs the range and resolution of the programmed
charger current.
V
this pin and GND. The value of the external resistor
programs the range and resolution of the charging volt-
age.
THB (Pin 15): SafetySignal Force/Sense Pin to Smart
Battery. See description of operation for more detail. The
maximum allowed combined capacitance on THA, THB
and SafetySignal is 1nF (see Figure 4). A series resistor
54.9k needs to be connected between this pin and the
battery’s SafetySignal for this circuit to work correctly.
THA (Pin 16): SafetySignal Force/Sense Pin to Smart
Battery. See description of operation for more detail. The
maximum allowed combined capacitance on THA, THB
and SafetySignal is 1nF (see Figure 4). A series resistor
1130 needs to be connected between this pin and the
battery’s SafetySignal for this circuit to work correctly.
V
Circuitry. Bypass this pin with 0.1 F. Typically between
3.3V and 5V
V
Divider, which Provides Battery Voltage Feedback to the
Charger.
I
Current Mode PWM. Higher I
charging current in normal operation. A 0.0015 F capaci-
tor to GND filters out PWM ripple. Typical full-scale output
current is 40 A. Nominal voltage range for this pin is 0V
to 3V.
I
CSP (Pin 21): Current Amplifier CA1 Input. This pin and
the BAT pin measure the voltage across the sense resistor,
R
quired for both peak and average current mode operation.
BAT (Pin 22): Battery Sense Input and the Negative
Reference for the Current Sense Resistor. A bypass ca-
pacitor of at least 10 F is required.
LIM
TH
DC
LIM
DD
SET
SENSE
(Pin 20): Bypass to GND with a 0.082 F Capacitor.
(Pin 19): Control Signal of the Inner Loop of the
(Pin 17): Power Supply Input for the LTC4100 Digital
(Pin 13): An external resistor is connected between
(Pin 14): An external resistor is connected between
(Pin 18): Tap Point of the Programmable Resistor
, to provide the instantaneous current signals re-
DC
.
TH
corresponds to higher
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