TPS54062

SLVSAV1B – MAY 2011 – REVISED AUGUST 2012

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OVERVIEW

The TPS54062 device is a 60 V, 50 mA, step-down (buck) regulator with an integrated high side and low side n-

channel MOSFET. 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 100 kHz to 400 kHz allows for efficiency and size optimization when selecting the

output filter components. The switching frequency is adjusted using a resistor to ground on the RT/CLK pin. The

device has an internal phase lock loop (PLL) on the RT/CLK pin that is used to synchronize the power switch

turn on to a falling edge of an external system clock.

The TPS54062 has a default start up voltage of approximately 4.5V. The EN pin has an internal pull-up current

source that can be used to adjust the input voltage undervoltage lockout (UVLO) threshold with two external

resistors. In addition, the pull up current provides a default condition. When the EN pin is floating the device will

operate. The operating current is 89uA when not switching and under no load. When the device is disabled, the

supply current is 1.7µA.

The integrated 1.5

Ω high side MOSFET and 0.8Ω low side MOSFET allows for high efficiency power supply

designs capable of delivering 50 milliamperes of continuous current to a load.

The TPS54062 reduces the external component count by integrating the boot recharge diode. The bias voltage

for the integrated high side MOSFET is supplied by a capacitor on the BOOT to PH pin. 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 TPS54062 can operate at high duty cycles because of the boot UVLO. The output

voltage can be stepped down to as low as the 0.8 V reference.

The TPS54062 has an internal output OV protection that disables the high side MOSFET if the output voltage is

109% of the nominal output voltage.

The TPS54062 reduces external component count by integrating the slow start time using a reference DAC

system.

The TPS54062 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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