Hi9001A

Hi9001A is a synchronous step-down BUCK converter with integrated high-side and low-side power MOSFETs. It delivers a continuous output current of up to 2A, and the ACOT control mode provides excellent load transient response. Under light-load conditions, the switching frequency is reduced to minimize switching losses, achieving high conversion efficiency across a wide load range. Built-in protection features include cycle-by-cycle current limiting, hiccup-mode short-circuit protection, and over-temperature protection. The integrated frequency dithering function enables easy compliance with EMI testing. Hi9001A is a synchronous step-down switching-mode converter IC using ACOT control mode, which enables fast transient response and a more stable control loop. The duty cycle is determined jointly by the output voltage and input voltage. The enable pin (EN) is a digital control input — the device is enabled when EN exceeds 2V and shuts down when EN falls below 0.8V; the EN pin is internally clamped to a maximum of 6V. The undervoltage lockout (UVLO) function protects the device when the supply voltage is insufficient; an internal UVLO comparator monitors the input voltage, with a rising threshold of approximately 5.1V and a falling threshold of approximately 4V. The soft-start (SS) function prevents output voltage overshoot during startup. Upon startup, an internal soft-start voltage (VSS) ramps from 0V to 1V; when VSS is below the REF voltage, the error amplifier uses VSS as the reference, and when VSS exceeds the REF voltage, the REF voltage is used as the reference. The VSS ramp time is internally set to 4ms. Hi9001A features valley current limiting control. During the LS-FET on-time, the inductor current is monitored; when the inductor current reaches the valley current limit, the LS-FET triggers the limit comparator and the system enters OCP mode — the HS-FET waits until the valley current limit clears before turning on again. During HS-FET on-time, the inductor current is compared against the peak current limit; when the peak current limit is triggered, the Ton pulse terminates immediately and the output voltage drops until VFB falls below the undervoltage (UV) threshold, at which point the device enters hiccup mode and periodically attempts to restart. OCP is a non-latching protection. Thermal shutdown prevents the device from operating at excessively high temperatures — when the die temperature exceeds the upper threshold, the entire device shuts down and restarts when the temperature falls below the lower threshold. The output voltage is set via an external resistor divider, with a fixed reference voltage of 1.163V.

Applications

• Surveillance cameras
• Home appliances
• Multifunction printers
• Automotive
• Industrial control

Key features

• Wide input voltage range: 5.5~36V
• 2A continuous output current
• ACOT control mode
• Voltage accuracy ±1%
• Operating frequency 520K
• Light-load PFM with built-in spread spectrum for easy EMI compliance
• MOS on-resistance: 130mΩ/80mΩ
• Internal soft-start
• Output voltage adjustable from 1.16V
• OCP, short-circuit hiccup, OTP
• Package: SOT23-6