Описание
The bq24745 is a high-efficiency, synchronous battery charger with an integrated input-current comparator, offering low component count for space-constrained, multi-chemistry battery-charging applications. The input-current, charge-current, and charge-voltage DACs allow very high regulation accuracies that can be easily programmed by the system power-management microcontroller using the SMBus interface. The bq24745 charges two, three, or four series Li+ cells, and is available in a 28-pin, 5-mm × 5 mm QFN package. The bq24745 features dynamic power management (DPM) and input power limiting. These features reduce battery-charge current when the input power limit is reached to avoid overloading the ac adaptor when supplying the load and the battery charger simultaneously. A highly accurate current-sense amplifier enables precise measurement of input current from the ac adapter, allowing monitoring the overall system power. If the adapter current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its performance to the power available from the adapter. An integrated comparator monitors the input current through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold limit.
300-kHz Frequency and >95% Efficiency
99.5% Maximum Effective Duty Cycle
- ±0.5% Charge Voltage Accuracy
- ±3% Charge Current Accuracy
- ±3% Adapter Current Accuracy
- ±2% Input Current Sense Amp Accuracy
- Input Current Comparator, With Adjustable
Threshold and Hysteresis - Internal Soft-Start
- Dynamic Power Management (DPM)
- Charge Voltage DAC (1.024 V–19.2 V)
- Charge Current DAC (128 mA–8.064 A)
- Adapter Current Limit DPM DAC
(256 mA–11.008 A)
- AC/DC Adapter Present With
Adjustable Voltage Threshold - Input Current Comparator With Adjustable
Threshold and Hysteresis - Current Sense Amplifier for Current Drawn
From Input Source
NiMH, Lead Acid, Etc.
Present and Charge Disabled
