ADPL12008/ADPL12010

20V, 8A/10A Fully Integrated Buck Converter

with 20μA Quiescent Current and Dual-Phase

Capability

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Detailed Description

The ADPL12008/ADPL12010 ICs are highly integrated synchronous buck converters with integrated high-side and low-

side switches. The ICs are designed to deliver up to 8A/10A current with input voltages from 3V to 20V while using only

20μA quiescent current at no load condition. The voltage quality can be monitored by the PGOOD signal. The ICs can

operate in dropout mode by running at a very high duty cycle, making them ideal for factory automation applications.

The ADPL12008/ADPL12010 ICs offer adjustable output voltage programmed by an external resistor-divider. The

frequency is internally fixed at 1.5MHz and 400kHz options, allowing for the use of small external components and

reduced output ripple. The signal at SYNC programs the ICs in skip enable, FPWM, or when synchronizing to the external

clock. Average current-mode control with 36ns minimum ON time allows for large input/output step-down ratios without

skipping cycles.

The ADPL12008/ADPL12010 ICs can also be configured in dual-phase mode to supply up to a 20A load. The average

current-mode control provides noise immunity and accurate dynamic current sharing during transients.

The FC2QFN package lowers the package parasitic impedance and improves the thermal performance. A symmetrical

pinout placement of SUP and PGND provides a balanced current loop around the ICs and further improves their EMI

performance.

Linear Regulator Output (BIAS)

The devices include a 1.8V linear regulator (VBIAS) that powers the internal circuit blocks. Connect a 2.2μF ceramic

capacitor from BIAS to GND. During startup, the bias regulator draws power from the input and switches over to the output

after the startup is completed (if VOUT > 2.5V).

Synchronization Input (SYNC)

The ADPL12008/ADPL12010 ICs provide an internal oscillator with 400kHz and 1.5MHz options. Drive SYNC high for

FPWM operation with 400kHz or 1.5MHz switching frequency. Drive SYNC low to enable skip-mode for better efficiency

improvement at light load. The ICs can be synchronized to the external clock with a valid external clock present at SYNC.

Enable Input (EN)

An Enable Input (EN) enables the ICs from shutdown mode. Drive EN high to enable the ICs. Drive EN low to disable the

ICs into shutdown mode. The quiescent current is reduced to 4μA (typ) during shutdown.

Soft-Start

Drive EN high to enable the ICs. The soft-start circuitry gradually ramps up the reference voltage during the soft-start time

(2.5ms at 400kHz or 3.5ms at 1.5MHz, typ) to reduce the input inrush currents during startup.

Short-Circuit Protection

The ICs feature a cycle-by-cycle current limit and hiccup mode to protect against short-circuit or overload conditions. In

overload conditions, the high-side FET remains on until the inductor current reaches the current limit threshold, ILIM.

Then, the converter turns off the high-side FET and turns on the low-side FET, allowing the inductor current to ramp down.

Once the inductor current decreases to the valley current limit, the converter turns on the high-side FET again. This cycle

repeats until the overload condition is removed.

A short-circuit is detected when the output voltage falls below the preset threshold voltage while the inductor current hits

the current limit. The threshold voltage is 25% of output regulation voltage. During hiccup-mode, the ICs turn off the buck

converter for 35ms (10x soft-start time, fSW = 1.5MHz), and then restart it if the overcurrent or short-circuit condition is

removed. The hiccup repeats when the short-circuit is continuously present.

Power Good Indicator (PGOOD)

The ICs feature an open-drain Power Good (PGOOD) output to indicate the output voltage status. The PGOOD goes low

to high impedance when the converter output voltage rises above 94% (typ) of its nominal regulation voltage. The PGOOD

goes low when the output voltage drops below 93% (typ) of the nominal regulation voltage. Connect PGOOD to the

converter output or BIAS voltage through a pull-up resistor. The PGOOD asserts low during soft-start.