TPS54062_16 Datasheet, PDF (11/42 Pages) Texas Instruments – 4.7-V to 60-V Input, 50-mA Synchronous Step-Down Converter With Low IQ

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7 Detailed Description
TPS54062
SLVSAV1D – MAY 2011 – REVISED JULY 2016
7.1 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 4.5 V. The EN pin has an internal pullup current
source that can be used 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 will
operate. The operating current is 89 µA when not switching and under no load. When the device is disabled, the
supply current is 1.7 µA.
The integrated 1.5-Ω high-side MOSFET and 0.8-Ω low-side MOSFET allows for high efficiency power supply
designs capable of delivering 50-mA 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 start-up and
overcurrent fault conditions to help control the inductor current.
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