LLTC4100EG View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LLTC4100EG' PDF : 30 Pages View PDF
LTC4100
Operation
Controlled Charging Algorithm Overview
The following conditions must be met in order to allow
controlled charging to start on the LTC4100:
1. The ChargingVoltage() AND ChargingCurrent() function
must be written to non-zero values.
2. The SafetySignal must be RES_COLD, RES_IDEAL, or
RES_UR.
3. AC must be present. This is qualified by DCDIV > VACP.
The following conditions will stop the controlled charging
algorithm and will cause the battery charger controller to
stop charging:
1. The ChargingCurrent() AND ChargingVoltage() functions
have not been written for TTIMEOUT.
2. The SafetySignal is registering RES_OR.
3. The SafetySignal is registering RES_HOT.
4. The AC power is no longer present. (DCDIV < VACP)
5. ALARM_INHIBITED is set in the ChargerStatus()
function.
6. INHIBIT_CHARGE is set in the ChargerMode()
function. Clearing INHIBIT_CHARGE will cause the
LTC4100 to resume charging using the previous
ChargingVoltage() AND ChargingCurrent() function
values.
7. RESET_TO_ZERO is set in the ChargerMode() function.
8. CHGEN pin is pulled low by an external device. The
LTC4100 will resume charging using the previous
ChargingVoltage() AND ChargingCurrent() function
values, if the CHGEN pin is released by the external
device.
9. Insufficient DCIN voltage to charge the battery. The
LTC4100 will resume charging using the previous
ChargingVoltage() AND ChargingCurrent() function
values, when there is sufficient DCIN voltage to charge
the battery.
10. Writing a zero value to ChargingVoltage() function.
11. Writing a zero value to ChargingCurrent() function.
The SafetySignal Decoder Block
This block measures the resistance of the SafetySignal and
features high noise immunity at critical trip points. The low
power standby mode supports only battery presence SMB
charger reporting requirements when AC is not present.
The SafetySignal decoder is shown in Figure 4. The value
of RTHA is 1.13k and RTHB is 54.9k.
VDD
RTHA
1.13k
16
THA
THA_SELB
VDD
RTHB
54.9k
15
THB
CSS RSafetySignal
THB_SELB
MUX
+
–
HI_REF
+
REF
–
LO_REF
SafetySignal
CONTROL
RES_OR
LATCH
RES_COLD
RES_H0T
RES_UR
TH_HI
TH_LO
VDD
12.5k
+
33k
25k
–
+
VLIM 14
25k
–
+
RVLIM
25k
–
+
12.5k
–
AC_PRESENT
ENCODER
4
VLIM [3:0]
Figure 4. SafetySignal Decoder Block
4100 F04
4100 F05
Figure 5. Simplified VLIM Circuit Concept (ILIM is Similar)
For more information www.linear.com/LTC4100
4100fc
17
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