MP2166

– 6V, DUAL 2A/2A OR 3A/1A, SYNC, BUCK REGULATOR WITH PG AND SS

MP2166 Rev. 1.0

www.MonolithicPower.com

15

3/14/2017

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Oscillator and Sync Function

The internal oscillator frequency is set by a single

FREQ and ground. The frequency setting resistor

should be located close to the device. The

relationship between the oscillator frequency and

FREQ can also be used to synchronize the

internal oscillator to an external clock. The

rising

edge

of

the

channel

1

clock

is

synchronized to the external clock rising edge,

while the channel 2 clock remains at 180°out-

of-phase to channel 1. The recommended

external SYNC frequency is in the range of

350kHz to 3MHz. While there is no pulse width

requirement, note that there is always parasitic

capacitance of the pad there, so if the pulse

width is too short, a clear rising and falling edge

may not be seen. The pulse is recommended to

be longer than 100ns.

Power Good (PG)

The MP2166 has one power good (PG) output

to indicate normal operation after the soft-start

time. PG is the open drain of an internal

MOSFET. It should be connected to VIN, VCC,

or an external voltage source through a resistor

(i.e.: 100k

Ω). After the input voltage is applied,

the MOSFET is turned on and PG is pulled to

GND before SS is ready. After the FB voltage

the MOSFET turns off and PG is pulled high by

an external voltage source. When the FB

pulled to GND to indicate a failure output.

Current Limit and Short Circuit

Each channel of the MP2166 has a typical 4.5A

current limit for the high-side switch. When the

current limit condition is sustained for a pre-

defined period of time, the MP2166 treats this

as a short and attempts to recover with hiccup

mode.

In hiccup mode, the MP2166 disables the output

power stage, slowly discharges the soft-start

cap, and soft starts automatically. If the short-

circuit condition still remains, the MP2166

repeats this operation cycle until the short

circuit is removed and the output rises back to

regulation levels.

Dropout Operation

The MP2166 allows the high-side switch to

remain on for more than one switching cycle and

increases the duty cycle while the input voltage

drops down to the output voltage. When the duty

cycle reaches 100%, the high-side switch is on to

deliver current to the output up to its current limit.

The output voltage is then the difference between

the input voltage and the voltage drop across the

main switch and the inductor.