ADP2138and ADP2139 are high efficiency, low electrostatic current, synchronousStep-down DC-DC converter。 The ADP2139 additionally adds an internal discharge switch. The entire solution requires only three small external components. When the MODE pin is set high, the buck regulator operates in forced PWM mode, providing low peak-to-peak ripple for power supply noise-sensitive loads at the expense of light load efficiency. When the MODE pin is set low, the buck regulator automatically switches mode of operation based on the load current level. At high output loads, the buck regulator operates in PWM mode. When the load current drops below a predefined threshold, the regulator operates in power-down mode (PSM) to improve light load efficiency.
The ADP2138/ADP2139 operate from an input voltage of 2.3 V to 5.5 V and can be powered by a single lithium or Li-polymer battery, multiple alkaline or NiMH batteries, PCMCIA, USB, and other standard power supplies. A maximum load current of 800mA can be achieved over the entire input voltage range.
The ADP2138/ADP2139 are available in fixed output voltages of 3.3 V, 3.0 V, 2.8 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V, 1.0 V, and 0.8 V. All models have built-in power switches and synchronous rectifiers to reduce the number of external parts and improve efficiency. The ADP2138/ADP2139 have a built-in soft-start function and internal compensation. During a logic-controlled shutdown, the input is disconnected from the output, and the ADP2138/ADP2139 draw 0.2 μA typical from the input source.
Other important features include undervoltage lockout to prevent deep battery discharge and soft-start to prevent input current overshoot at startup. The ADP2138/ADP2139 are available in a 6-lead wafer-level chip scale package (WLCSP).
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- PDAs and PDAs
- Wireless phones
- Digital audio, portable media player
- Digital cameras, GPS navigation devices
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Advantages and features
- Input voltage: 2.3 V to 5.5 V
- Peak efficiency: 95%
- 3 MHz fixed operating frequency
- Typical quiescent current: 24 μA
- Extremely small size solution
6-pin, 1 mm × 1.5 mm WLCSP packages
- Fast loading and line transient response
- Duty cycle: 100% (low dropout mode)
- Internal synchronous rectifier, compensation, and soft-start
- Current overload and thermal shutdown protection
- Ultra-low shutdown current: 0.2 μA typical
- Forced PWM and Auto PWM/PSM modes
- ADIsimPower design tool support