Tokmas MP2451DT-LF-Z(TOKMAS)

MP2451DT is a high-frequency (1.8MHz) step-down switching regulator with an integrated internal high-side high-voltage power MOSFET. It employs current-mode control to deliver a single 0.6A (or lower) high-efficiency output with fast loop response. Its wide input voltage range (4.2V to 40V) makes it suitable for a variety of step-down applications under mobile environment input conditions. The 1μA low shutdown quiescent current is ideal for battery-powered applications. Under light-load conditions, high efficiency is achieved by reducing switching frequency to minimize switching and gate drive losses. Frequency foldback technology helps prevent inductor current runaway during startup. Thermal shutdown ensures reliable, fault-tolerant operation. The MP2451DT is a 1.8MHz non-synchronous step-down switching regulator with an integrated internal high-side MOSFET, providing a single internally compensated 0.6A high-efficiency output with a wide input voltage range, internal soft-start control, and precise current limiting. The low operating quiescent current characteristic makes it well suited for battery-powered applications. Under heavy or moderate load conditions, the MP2451DT operates in fixed-frequency, peak current control mode to regulate the output voltage. The PWM cycle is initiated by an internal clock; the power MOSFET turns on and remains on until its current reaches the value set by the COMP voltage. When the power switch turns off, it remains off for at least 100ns before the next cycle begins. Under light-load conditions, the circuit enters pulse-skip mode to improve light-load efficiency. The pulse-skip determination is based on the internal COMP voltage. When the COMP pin falls below the internal sleep threshold, a sleep command is generated that blocks clock pulses from turning on, preventing the power MOSFET from being commanded on, thereby saving drive and switching losses. The sleep command also places the entire chip into sleep mode, consuming extremely low quiescent current to further improve light-load efficiency. The error amplifier consists of an internal op-amp and an RC feedback network connected between its output (internal COMP node) and its negative input (FB). When FB falls below its internal reference voltage (REF), the op-amp drives the COMP output higher, resulting in a higher peak switch current output and more energy transferred to the output, and vice versa. Typically, FB is connected to a voltage divider formed by RUP and RDN, where RDN is connected between FB and ground, and RUP is connected between the voltage output node and FB. RUP, together with the internal compensation RC network, controls the gain of the error amplifier. Most of the internal circuitry is powered by a 2.6V internal regulator. When VIN is above 4.0V, the regulator output is fully regulated; when VIN is lower, output performance degrades. The circuit has a dedicated enable control pin EN. When VIN is sufficiently high, the chip can be enabled or disabled via the EN pin, active high, with a rising threshold of 1.6V and a falling threshold of 0.6V. When in sleep mode, the EN pin is internally pulled to ground and the chip is disabled. When EN reaches 0V, the chip enters minimum shutdown current mode. When EN is above zero but below its threshold, the chip remains in shutdown mode with a slightly increased shutdown current. The VIN undervoltage lockout (UVLO) function protects the chip from operating when the supply voltage is insufficient. Soft-start is used to prevent output voltage overshoot during converter startup. When the chip starts up, the internal circuitry generates a soft-start voltage (SS) that begins at 0V and rises slowly over the soft-start duration. When SS is below the internal reference REF, SS takes precedence and the error amplifier uses SS instead of REF as the reference. When SS exceeds REF, REF takes precedence. SS is also associated with FB — SS can be much lower than FB, but can only be slightly higher than FB. If FB drops unexpectedly, SS also tracks downward; this feature is designed to handle short-circuit recovery. When the short circuit is removed, SS ramps up, serving as a soft-start process for restart and preventing output voltage overshoot. The thermal shutdown function prevents the chip from thermal runaway. When the temperature exceeds the upper threshold, the MP2451DT shuts down; when the temperature falls below the lower threshold, the chip is re-enabled.

• 0.6A peak output current
• 230μA quiescent operating current
• 4.2V to 40V operating input range
• 500mΩ internal power MOSFET
• 1.8MHz fixed switching frequency
• Internal compensation
• Stable with ceramic output capacitors
• Internal soft-start
• Accurate current limiting without current sense resistor
• Efficiency >90%
• Low shutdown current: <1μA
• SOT23-6 package

• High-voltage power conversion
• Automotive systems
• Industrial power systems
• Distributed power systems
• Battery-powered systems