The ADP1821 is a versatile and inexpensive, synchronous, pulse-width-modulated (PWM), voltage-mode, step-down controller. It drives an all N-channel power stage to regulate an output voltage as low as 0.6 V. The ADP1821 can be configured to provide output voltages from 0.6 V to 85% of the input voltage and is sized to handle large MOSFETs for point-of-load regulators.
The ADP1821 is well suited for a wide range of high power applications, such as DSP and processor core power in telecommunications, medical imaging, high performance servers, and industrial applications. It operates from a 3.7 V to 5.5 V supply with a power input voltage ranging from 1.0 V to 24 V.
The ADP1821 operates at a pin-selectable, fixed switching frequency of either 300 kHz or 600 kHz, minimizing external component size and cost. For noise sensitive applications, it can be synchronized to an external clock to achieve switching frequencies between 300 kHz and 1.2 MHz. The ADP1821 includes soft start protection to limit the inrush current from the input supply during startup, reverse current protection during soft start for precharged outputs, as well as a unique adjustable lossless current-limit scheme utilizing external MOSFET sensing.
The ADP1821 operates over the –40°C to +125°C junction temperature range and is available in a 16-lead QSOP.
**Applications**
Telecommunications and networking systems
Set-top boxes
Printers
Servers
Medical imaging systems
Microprocessor and DSP core power supplies
Mobile communication base stations
### Features and Benefits
Wide power-input voltage range: 1 V to 24 V
Chip supply voltage range: 3.7 V to 5.5 V
Wide output voltage range: 0.6 V to 85% of input voltage
1% accuracy, 0.6 V reference voltage
All N-channel MOSFET design for low cost
Fixed-frequency operation 300 kHz, 600 kHz, or synchronized operation up to 1.2 MHz
No current sense resistor required
Power-good output
Programmable soft start with reverse current protection
