ST4312 1.21V CV/CC Controller
Specifications
Product details
Overview
The ST4312 is a highly integrated solution for switch-mode power supplies requiring dual control loops for constant voltage (CV) and constant current (CC) regulation. It integrates a precision ±1% 1.21V voltage reference (±0.5% for ST4312C), a 74mV low-voltage reference (212mV for ST4312C), an externally adjustable ultra-low voltage reference, and three operational amplifiers. The 1.21V reference with one op-amp generates an ideal voltage setpoint for power adapters and battery chargers, while the low-voltage reference with another op-amp produces an ideal current-limit threshold for output current sensing and CC control. The ST4312A integrates a 9mV reference with an op-amp for an LED indicator control circuit adjustable via the ICTRL pin: during charging the red LED is on and green is off, and when charging current drops to 12% of the limit, green turns on with an 11% hysteresis preventing bouncing; the ST4312B/C allow adjustable LED switching thresholds via an external resistor on ICTRL.
Features
- Constant voltage (CV) and constant current (CC) control
- Precision internal voltage reference
- Minimal external component count
- Easy compensation
- Adjustable LED indicator (charging status) circuit
- Ultra-wide operating voltage range: 3V to 40V
- Low quiescent current
- Charging status indicator function
- Few external components, low overall system cost
Typical Applications
- Power adapters
- Battery chargers
