Protection IC for 12V Bus with an Integrated MOSFET and Lossless Current SensingApril 16, 2020 by Paul Shepard
The MAX16545B/C from Maxim Integrated Products is a circuit-breaker protection IC with an integrated low-resistance MOSFET and lossless current-sense circuitry featuring PMBus™/SMBus control and reporting. The IC is designed to provide the optimum solution for distribution, control, monitoring and protection of the system’s 12V power supply. An internal LDO provides the bias supply voltage for the protection IC.
If no fault is detected, the MAX16545B/C initiates the startup. The device has been designed to provide controlled, monotonic startup. Programmable soft-start ramp and delay is implemented to limit the inrush current during startup. The MAX16545B is set for 16A Startup OCP, and the MAX16545C is set for 24A Startup OCP.
The IC monitors the current and the voltage of the 12V system power rail and provides multiple levels of protection with fast turn off if a fault is detected. Three methods of overcurrent protection are provided. Programmable moderate OCP level allows surge currents for a limited time. User-selectable severe OCP level provides a fast disconnect if a current exceeding the severe OCP threshold is detected. An additional fixed high shutdown OCP level provides instantaneous disconnect to further protect the device.
The lossless current sense provides high-accuracy current sensing over load and temperature, improving overall system energy efficiency, and reducing dissipation. A signal proportional to the load current is reported through an analog output and extensive reporting is provided through the SMBus/PMBus.
Output voltage is monitored at all times. If at any time the output voltage falls below the programmable output undervoltage lockout threshold, the PWRGD signal is asserted low. If at any time the input voltage falls below the programmable input undervoltage lockout threshold, the PWRGD signal is asserted low.
The MAX16545B/C can be programmed through PMBus to provide input overvoltage protection. Input overvoltage protection is disabled by default. When enabled through PMBus, if the input voltage exceeds a programmable overvoltage threshold, the MOSFET is latched off and a fault is communicated.
- High Density (6.5mm × 4mm for 60A): Less than 25% of the Board Area of Conventional Solutions
- Monolithic Integration of Power, Control, and Monitoring (Integrated Power MOSFET with 0.9mΩ Total Resistance in 12V Power Path (RDSON), Including Package)
- Integrated Lossless, Precise Current Sensing
- Integrated LDO Provides VDD Supply (1.8V Bias Supply)
- Enables Advanced System Power Management
- PMBus/SMBus Telemetry with Extensive Status Monitoring and Reporting
- Load Current Indicator (ILOAD) Pin Provides Analog Output Current Reporting With High Accuracy
- Programmable Soft-Start for Inrush Current Limiting
- Increases Power-Supply Reliability with IC Self-Protection Features
- Very Fast Fault Detection and Isolation
- VIN to VOUT Short Protection During Startup
- Overtemperature Protection
- Three Levels of Overcurrent Protection
- Programmable Moderate OCP
- Programmable Severe OCP Provides Isolation<5µs.
- Fail-Safe Safe OCP Provides Isolation <250ns.