Texas Instruments' TPS54325 is a 3-A synchronous step-down DC/DC converter that employs an easy to use adaptive on-time (D-CAP2™ mode) architecture enabling a fast transient response time without compensation components. The device is designed for use with low cost output capacitors, such as aluminum electrolytic capacitors or a 22 µF low ESR ceramic output capacitor. It operates from 4.5 V to 18 V VCC input, and from a 2.0 V to 18 V power stage supply voltage. The output voltage can be programmed between 0.76 V and 5.5 V with a voltage divider. The device features an adjustable soft-start, enable, power good output.
Why was this product developed?
Newer ASICs, even in consumer electronics applications, have more stringent load demands with faster slew rates. The power supply needs to react quickly to large changes in processor activity and current demands while keeping core voltage overshoots and undershoots at a minimum. The TPS54325 with the D-CAP2™ mode allows a fast transient response time with less ripple; while using a small amount of ceramic capacitance that keeps cost down.
Functional Block Diagram
- Fast adaptive on-time (D-CAP2™) control architecture
- Integrated 120 mΩ high-side and 70 mΩ low-side MOSFETs
- Fixed 700 kHz switching frequency
- Adjustable soft-start time
- Power good and enable pins
- High performance with 2x22 µF ceramic Cout
- Faster than 20 µs transient response time (0-3A step)
- Less than 10 mVp-p output voltage ripple
- No compensation components needed
- 90% efficiency at 3 A; optimized for low Vout
- Allows 50% smaller inductor value than 350 kHz
- Reduces inrush currents during startup
- Easily implement sequencing schemes
- Digital TV
- High definition Blue-ray Disc™ player
- Networking home terminal
- Digital set top box