MP2176 – 6V, 6A, SYNCHRONOUS, STEP-DOWN CONVERTER

MP2176 Rev. 1.0

www.MonolithicPower.com

16

4/17/2018

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start capacitor exceeds the sensed output

voltage at FB. There is an internal Zener diode

on EN, which clamps the EN voltage to prevent

a runaway. Assuming a worst-case 6V internal

Zener clamp, the maximum pull-up current

should be less than 1mA. Therefore, when EN

is driven by an external logic signal, the EN

voltage should be lower than 6V. When EN is

connected to IN through a pull-up resistor or a

resistive

voltage

divider,

the

resistance

selection should ensure that the maximum pull-

up current is less than 1mA.

If using a resistive voltage divider and an IN

value higher than 6V, the allowed minimum

pull-up resistor (RUP) should meet Equation (11):

IN

UP

DOWN

V (V) 6

6

1(mA)

R (k )

R

(k )







(11)

As a result, when only RUP is applied, VIN-START

is

determined

by

the

input

under-voltage

lockout (UVLO). The value of RUP can be

calculated with Equation (12):

IN

UP

V (V)

6

R (k )

1(mA)





(12)

A typical pull-up resistor is 100k

Ω.

Thermal Shutdown

Thermal shutdown is employed in the MP2176.

The junction temperature of the IC is monitored

internally. If the junction temperature exceeds

the threshold value (minimum 150°C), the

converter

shuts

off.

This

is

a

non-latch

protection. There is a hysteresis of about 25°C.

Once the junction temperature drops to about

125°C, a soft start-up is initiated.

Under-Voltage Lockout (UVLO) Protection

The MP2176 has a UVLO protection. When

VCC is higher than the UVLO rising threshold

voltage, the MP2176 is powered up. The

MP2176 shuts off when VCC is lower than the

UVLO falling threshold voltage. This is a non-

latch protection.

The MP2176 is disabled when VCC falls below

its

UVLO falling

threshold

(2.45V).

If

an

application requires a higher UVLO, use EN to

adjust the input voltage UVLO by using two

external

resistors

(see

Figure

6).

It

is

recommended to use the EN resistors to set the

UVLO falling threshold (VSTOP) above 2.8V. The

rising threshold (VSTART) should be set to

provide enough of a hysteresis to allow for any

input supply variation.

Figure 6: Adjustable UVLO