The LM5121 is a synchronous boost controller intended for high-efficiency, high-power boost regulator applications. The control method is based upon peak current mode control. Current mode control provides inherent line feed-forward, cycle-by-cycle current limiting and ease of loop compensation.
The switching frequency is programmable up to 1 MHz. Higher efficiency is achieved using two robust N-channel MOSFET gate drivers with adaptive dead-time control. A user-selectable diode emulation mode enables discontinuous mode operation for improved efficiency at light load conditions.
The LM5121 provides disconnection switch control which completely disconnects the output from the input during an output short or a shutdown condition. During start-up sequence, inrush current is limited by the disconnection switch control.
An internal charge pump allows 100% duty cycle operation of the high-side synchronous switch (Bypass operation). Additional features include thermal shutdown, frequency synchronization, hiccup mode current limit and adjustable line undervoltage lockout.
AEC-Q100 Grade 1 (TA = –40ºC to 125ºC)
Maximum Input Voltage: 65 V
Min Input Voltage: 3.0 V (4.5 V for startup)
Output Voltage Up to 100 V
Bypass (VOUT = VIN) Operation
1.2-V Reference with ±1.0% Accuracy
Free-Run/Synchronizable up to 1 MHz
Peak Current Mode Control
Robust Integrated 3-A Gate Drivers
Adaptive Dead-Time Control
Optional Diode Emulation Mode
Programmable Cycle-by-Cycle Current Limit
Programmable Line UVLO
Thermal Shutdown Protection
Low Shutdown Quiescent Current: 9 µA
Programmable Slope Compensation
Programmable Skip Cycle Mode Reduces Standby Power
Supports External VCC Bias Supply Option
Load Disconnection in Shutdown Mode (True Shutdown)