MP8606

– 6A, 6.5V SYNCHRONOUS STEP-DOWN CONVERTER

MP8606 Rev. 1.03

www.MonolithicPower.com

13

8/2/2013

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© 2013 MPS. All Rights Reserved.

SS time is programmable through the capacitor

connected between SS pin and AGND.

When the EN pin goes low, an internal current

source discharges the internal SS voltage. Once

voltage.

The

output

voltage

will

decrease

smoothly with the SS voltage until the voltage

level zeros out.

Power-Good (PG)

The PG pin is the open drain of a MOSFET that

through a resistor (ex. 100k). The MOSFET turns

on with the application of an input voltage so that

the PG pin is pulled to GND before SS is ready.

is pulled high after a 0.5ms delay.

PG pin will be pulled low.

Over-Current Protection (OCP) and Short-

Circuit Protection (SCP)

MP8606 has cycle-by cycle over-current limit

control. The inductor current is monitored during

the ON state.

For MP8606DL, the HS-FET turns off when the

inductor current exceeds the current limit and the

OCP timer

—set at 50μs—starts. The OCP

triggers

if

the

inductor

current

reaches

or

exceeds the current limit every cycle in those

50

μs. The MP8606 short-circuit protection (SCP)

occurs when dead shorts occur

—when the

inductor current exceeds the current limit and the

For MP8606DL, it enters hiccup mode, during

SCP/OCP. It periodically restarts the part when

the inductor peak current exceeds the current

threshold. Typically, the UV threshold is 50%

below the REF voltage. In OCP/SCP, MP8606DL

will

disable

both

the

HSFET

and

LSFET,

discharge

internal

soft-start

cap,

and

then

automatically try to soft-start again. If the over-

current circuit condition still holds after soft-start

ends, it repeats this operation cycle until the

over-current circuit condition disappears, and

output rises back to regulation level.

Over/Under-voltage Protection (OVP/UVP)

MP8606 monitors the output voltage through a

resistor-divided feedback (FB) voltage to detect

over and under voltage on the output. When the

trigger the OVP. Once it triggers the OVP, the

LS-FET is always on while the HS-FET is off. It

needs

to

power

cycle

to

turn

on

again.

Conversely, the UVP triggers when the FB

Usually UVP accompanies a drop in the current

limit and this results in SCP.

UVLO protection

MP8606 has under-voltage lock-out protection

(UVLO). When the input voltage is higher than

the UVLO rising threshold voltage, the MP8606

powers up. It shuts off when the input voltage is

lower than the UVLO falling threshold voltage.

This is non-latch protection.

Thermal Shutdown

The MP8606 employs thermal shutdown by

internally monitoring the junction temperature of

the IC. If the junction temperature exceeds the

threshold value (typically 150ºC), the converter

shuts off. This is non-latch protection. There is

about

20ºC

hysteresis.

Once

the

junction

temperature drops around 130ºC, it initiates a

soft start.