Datasheet LTC1980 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | Combination Battery Charger and DC/DC Converter |
| Pages / Page | 16 / 7 — PI FU CTIO S. REG (Pin 15):. ISENSE (Pin 21):. CAOUT (Pin 22):. MODE (Pin … |
| File Format / Size | PDF / 245 Kb |
| Document Language | English |
PI FU CTIO S. REG (Pin 15):. ISENSE (Pin 21):. CAOUT (Pin 22):. MODE (Pin 16):. OVP (Pin 23):. TIMER (Pin 17):. VBAT (Pin 18):
Model Line for this Datasheet
Text Version of Document
LTC1980
U U U PI FU CTIO S REG (Pin 15):
Bidirectional Regulator Mode Control Pin. A
ISENSE (Pin 21):
Current Sense Input Pin. Connects inter- pull-up resistor is required between this pin and VBIAS2. nally to a current amplifier and zero current comparator. This pin is open when charging normally, has a weak pull- This pin should Kelvin-connect to the current sense resis- down (approximately 5µA) when conditioning the battery tor (RSENSE) . and a strong pull-down when in regulator mode. Pulling
CAOUT (Pin 22):
Current Amplifier Output. A program this pin low forces the IC into regulator mode. resistor connects between this pin and PROGT (Pin 2) to
MODE (Pin 16):
Selects different operating modes in both set the charge current (in constant-current mode). charger and DC/DC converter configurations. Also en-
OVP (Pin 23):
Overvoltage Protection. This pin connects ables and disables Burst Mode operation. See Mode Pin to the tap on an optional external voltage divider con- Operation table in Application section. nected across the battery. This allows nonstandard float
TIMER (Pin 17):
A timing capacitor on this pin determines voltages to be used for the battery charger. Overvoltage, the normal charge time for charge termination. restart and undervoltage thresholds will also be affected by the external voltage division ratio. To use this pin, C(µF) = 0.25 • Time (Hours) BATT1 (Pin 9) must float.
VBAT (Pin 18):
This pin connects to the positive terminal of
SS (Pin 24):
Soft-Start. A capacitor between this pin and the battery and the battery side of the power converter. ground sets the battery charge ramp rate. Battery charge
VBIAS2 (Pin 19):
Internally Generated Voltage. Bypass this current is very low the moment after the converter switches pin with a 1µF or larger ceramic capacitor (or other low from DC/DC converter (regulator) mode to battery charger ESR capacitor). Do not connect any load to this pin. mode then ramps up to final battery charge current from
GND (Pin 20):
Signal Ground. This pin should Kelvin- there. This insures that the wall adapter is not loaded down connect to the current sense resistor (R with a large inrush current that could prevent correct SENSE). battery charger operation. The same capacitor, which sets the soft-start ramp rate, also sets the compensation for the battery float voltage control loop. 1980f 7
U U U PI FU CTIO S REG (Pin 15):
Bidirectional Regulator Mode Control Pin. A
ISENSE (Pin 21):
Current Sense Input Pin. Connects inter- pull-up resistor is required between this pin and VBIAS2. nally to a current amplifier and zero current comparator. This pin is open when charging normally, has a weak pull- This pin should Kelvin-connect to the current sense resis- down (approximately 5µA) when conditioning the battery tor (RSENSE) . and a strong pull-down when in regulator mode. Pulling
CAOUT (Pin 22):
Current Amplifier Output. A program this pin low forces the IC into regulator mode. resistor connects between this pin and PROGT (Pin 2) to
MODE (Pin 16):
Selects different operating modes in both set the charge current (in constant-current mode). charger and DC/DC converter configurations. Also en-
OVP (Pin 23):
Overvoltage Protection. This pin connects ables and disables Burst Mode operation. See Mode Pin to the tap on an optional external voltage divider con- Operation table in Application section. nected across the battery. This allows nonstandard float
TIMER (Pin 17):
A timing capacitor on this pin determines voltages to be used for the battery charger. Overvoltage, the normal charge time for charge termination. restart and undervoltage thresholds will also be affected by the external voltage division ratio. To use this pin, C(µF) = 0.25 • Time (Hours) BATT1 (Pin 9) must float.
VBAT (Pin 18):
This pin connects to the positive terminal of
SS (Pin 24):
Soft-Start. A capacitor between this pin and the battery and the battery side of the power converter. ground sets the battery charge ramp rate. Battery charge
VBIAS2 (Pin 19):
Internally Generated Voltage. Bypass this current is very low the moment after the converter switches pin with a 1µF or larger ceramic capacitor (or other low from DC/DC converter (regulator) mode to battery charger ESR capacitor). Do not connect any load to this pin. mode then ramps up to final battery charge current from
GND (Pin 20):
Signal Ground. This pin should Kelvin- there. This insures that the wall adapter is not loaded down connect to the current sense resistor (R with a large inrush current that could prevent correct SENSE). battery charger operation. The same capacitor, which sets the soft-start ramp rate, also sets the compensation for the battery float voltage control loop. 1980f 7
