TPS54061-Q1

SLVSBM7 – MARCH 2013

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OVERVIEW

The TPS54061-Q1 device is a 60 V, 200 mA, step-down (buck) regulator with integrated high-side and low-side

n-channel MOSFETs. To improve performance during line and load transients, the device implements a

constant-frequency, current-mode control which reduces output capacitance and simplifies external frequency-

compensation design.

The switching frequency of 50 kHz to 1100 kHz allows for efficiency and size optimization when selecting the

output filter components. Adjustment of the switching frequency is by use of a resistor to ground on the RT/CLK

pin. The device has an internal phase-lock loop (PLL) on the RT/CLK pin that synchronizes the power-switch

turnon to a falling edge of an external system clock.

The TPS54061-Q1 has a default start-up voltage of approximately 4.5 V. The EN pin has an internal pullup

current source, a possible use of which is to adjust the input voltage undervoltage lockout (UVLO) threshold with

two external resistors. In addition, the pullup current provides a default condition. When the EN pin is floating, the

device operates. The operating current is 90 µA when not switching and under no load. When the device is

disabled, the supply current is 1.4 µA.

The integrated 1.5-

Ω high-side MOSFET and 0.8-Ω low-side MOSFET allow for high-efficiency power-supply

designs capable of delivering 200 milliamperes of continuous current to a load.

The TPS54061-Q1 reduces the external component count by integrating the boot recharge diode. A capacitor

between the BOOT and PH pins supplies the bias voltage for the integrated high-side MOSFET. The boot

capacitor voltage is monitored by an UVLO circuit and will turn the high side MOSFET off when the boot voltage

falls below a preset threshold. The TPS54061-Q1 can operate at high duty cycles because of the boot UVLO.

The output voltage can be adjusted down to as low as the 0.8 V reference.

The TPS54061-Q1 has an internal output OV protection that disables the high side MOSFET if the output voltage

is 109% of the nominal output voltage.

The TPS54061-Q1 reduces external component count by integrating the slow start time using a reference DAC

system.

The TPS54061-Q1 resets the slow start times during overload conditions with an overload recovery circuit. The

overload recovery circuit will slow start the output from the fault voltage to the nominal regulation voltage once a

fault condition is removed. A frequency foldback circuit reduces the switching frequency during startup and

overcurrent fault conditions to help control the inductor current.

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