Texas Instruments' TPS61251 device provides a power supply solution for products powered by a three-cell NiCd or NiMH battery or a one-cell Li-Ion or Li-polymer battery. The wide input voltage range is ideal to power portable applications like mobile phones, solid state drives (SSD), and wireless modems. The converter is designed to charge large capacitors in the Farad range to support battery back up applications. During capacitor charging, the TPS61251 works as a constant current source until VOUT has reached its programmed value. The charge current can be programmed by an external resistor RILIM and provides ±10% accuracy for the average input current limit.
The TPS61251 in combination with a reservoir capacitor allows the converter to provide high current pulses that would exceed the capability of the supplying circuit (PC slot, USB) and keeps the slot power safely within its capabilities. During light loads the device will automatically enter an enhanced power save mode (Snooze Mode), which allows the converter to maintain the required output voltage, while only drawing 2 µA from the battery. This will allow maximum efficiency at lowest quiescent currents.
The TPS61251 allows the use of small inductors and input capacitors to achieve a small solution size. During shutdown, the load is completely disconnected from the battery and will not discharge the battery or the charged bulk capacitor. The TPS61251 is available in an 8-pin QFN package measuring 2×2 mm (DSG).
- Resistor programmable input current limit
- Snooze mode draws only 2 µA (typ.) quiescent current
- Designed to charge large capacitor values in the Farad range
- Up to 92% efficiency
- Power good indicates appropriate output voltage level even in shut down
- VIN range from 2.3 V to 6.0 V
- Adjustable output voltage up to 6.5 V
- 100% duty-cycle mode when VIN > VOUT
- Load disconnect and reverse current protection
- Short circuit protection
- Typical operating frequency 3.5 MHz
- Available in a 2×2 mm QFN-8 package
- Current limited applications with high peak power loads (SSD, PCMCIA Tx bursts, memory, GPRS/GSM Tx)
- Li-Ion applications
- Battery backup applications
- Audio applications
- RF-PA buffer