The ISL78233AARZ and ISL78234 are highly efficient, monolithic, synchronous step-down DC/DC converters that can deliver 3A (ISL78233), or 4A (ISL78234) of continuous output current from a 2.7V to 5.5V input supply. The devices use current mode control architecture to deliver a very low duty cycle operation at high frequency with fast transient response and excellent loop stability.
The ISL78233AARZ and ISL78234 integrate a very low ON‑resistance P‑channel (35mΩ) high-side FET and N-channel (11mΩ) low‑side FET to maximize efficiency and minimize external component count. The 100% duty-cycle operation allows less than 200mV dropout voltage at 4A output current. The operation frequency of the Pulse-Width Modulator (PWM) is adjustable from 500kHz to 4MHz. The default switching frequency of 2MHz is set by connecting the FS pin high.
The ISL78233AARZ and ISL78234 can be configured for discontinuous or forced continuous operation at light load. Forced continuous operation reduces noise and RF interference, while discontinuous mode provides higher efficiency by reducing switching losses at light loads.
Fault protection is provided by internal Hiccup mode current limiting during short-circuit and overcurrent conditions. Other protection, such as overvoltage and over-temperature are also integrated into the device. A power-good output voltage monitor indicates when the output is in regulation.
The ISL78233AARZ and ISL78234 offer a 1ms Power-Good (PG) timer at power-up. When in shutdown, the ISL78233AARZ and ISL78234 discharge the output capacitor through an internal soft-stop switch. Other features include internal fixed or adjustable soft‑start and internal/external compensation.
The ISL78233AARZ and ISL78234 are available in a 3mmx3mm 16 Ld Thin Quad Flat (TQFN) Pb-free package and in a 5mmx5mm 16 Ld Wettable Flank Quad Flat No-Lead (WFQFN) package with an exposed pad for improved thermal performance. The ISL78233AARZ and ISL78234 are rated to operate across the temperature range of -40°C to +125°C.
Feature
- 2.7V to 5.5V input voltage range
- Very low ON-resistance FETs - P-channel 35mΩ and N‑channel 11mΩ typical values
- High efficiency synchronous buck regulator with up to 95% efficiency
- -1.2%/1% reference accuracy over temperature/load/line
- Complete BOM with as few as 3 external parts
- Internal soft-start - 1ms or adjustable
- Soft-stop output discharge during disable
- Adjustable frequency from 500kHz to 4MHz - default at 2MHz
- External synchronization up to 4MHz
- Over-temperature, overcurrent, overvoltage, and negative overcurrent protection
- Shared common device pinout allows simplified output power upgrades over time
- Tiny 3mmx3mm TQFN package
- AEC-Q100 qualified
