3-65V Wide Vin, Current Mode Synchronous Boost Controller with Multiphase Capability
The LM5122ZA from Texas Instruments is a multi-phase capable synchronous boost controller intended for high-efficiency synchronous 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.
Applications are expected to include a variety of 12-V, 24-V, and 48-V power systems such as wireless infrastructure, audio power supplies and high-current boost power supplies.
The switching frequency is programmable up to 1MHz. Higher efficiency is achieved by two robust N-channel MOSFET gate drivers with adaptive dead-time control.
A user-selectable diode-emulation mode also enables discontinuous-mode operation for improved efficiency at light load conditions.
An internal charge pump allows 100% duty cycle for high-side synchronous switch (bypass operation). A 180° phase shifted clock output enables easy multi-phase interleaved configuration.
Additional features include thermal shutdown, frequency synchronization, hiccup-mode current limit, and adjustable line undervoltage lockout.
LM5122ZA
The control mode of high-side synchronous switch can be configured as either forced PWM (FPWM) or diode emulation mode. Fault protection features include cycle-by-cycle current limiting, hiccup-mode overload protection, thermal shutdown and remote shutdown capability by pulling down the UVLO pin.
The UVLO input enables the controller when the input voltage reaches a user selected threshold, and provides a tiny 9-µA shutdown quiescent current when pulled low.
The soft-start feature helps the regulator to gradually reach the steady state operating point, thus reducing startup stresses and surges. The LM5122ZA regulates the feedback loop to the voltage on an external soft-start capacitor or the internal 1.2-V reference, whichever is lower.
The internal 10-µA soft-start current source gradually increases the voltage on the external soft-start capacitor. This results in a gradual rise of the output voltage starting from the input voltage level to the target output voltage.
Summary of features:
- Maximum Input Voltage: 65V
- Minimum Input Voltage: 3V (4.5V for Start-Up)
- Output Voltage up to 100V
- Bypass (VOUT = VIN) Operation
- 2-V Reference with ±1% Accuracy
- Free-Run and Synchronizable Switching to 1MHz
- Peak-Current-Mode Control
- Robust 3-A Integrated Gate Drivers
- Adaptive Dead-Time Control
- Optional Diode-Emulation Mode
- Programmable Cycle-by-Cycle Current Limit
- Hiccup-Mode Overload Protection
- Programmable Line UVLO
- Programmable Soft Start
- Thermal Shutdown Protection
- Low Shutdown Quiescent Current: 9 µA
- Programmable Slope Compensation
- Programmable Skip-Cycle Mode Reduces Standby Power
- Allows External VCC Supply
- Inductor DCR Current Sensing Capability
- Multi-phase Capability
The device is available in a thermally-enhanced 24-pin HTSSOP package featuring an exposed pad to aid in thermal dissipation.
