MP2276 datasheet(17/23 Pages) MPS

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MP2276

– 16V, 8A, HIGH EFFICIENCY, SYNC, STEP-DOWN CONVERTER

MP2276 Rev.1.0

www.MonolithicPower.com

3/22/2017

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

Over-Voltage Protection (OVP)

The MP2276 monitors the output voltage using

FB connected to the tap of a resistor divider to

detect an over-voltage condition. If VFB exceeds

116% of VREF, OVP is triggered. The controller

enters a dynamic regulation period. During this

period, the low-side negative current limit

increases to -8A. The LS-FET remains on until

it triggers the low-side negative current limit.

After hitting the low-side negative current limit,

the LS-FET is turned off momentarily for 80ns

and is then turned on again. This discharges

the output to keep it within the normal range.

The MP2276 exits this regulation period when

VFB falls below 102.5% of VREF.

Over-Temperature Protection (OTP)

The MP2276 has over-temperature protection

(OTP).

The

monitors

the

junction

temperature

internally.

the

junction

temperature

exceeds

the

threshold

value

(typically 150°C), the converter shuts off. There

is a hysteresis of about 20°C. Once the junction

temperature drops to about 130°C, soft start is

initiated.

Power Good (PG)

The MP2276 has a power good (PG) output.

PG is the open drain of a MOSFET. Connect

PG to VCC or another external voltage source

less than 3.6V through a pull-up resistor

(typically 100

kΩ). After applying the input

voltage, the MOSFET turns on so that PG is

pulled to GND before the internal soft-start

voltage is ready. After VFB reaches 92.5% of

VREF, PG is pulled high after a 1ms delay.

When VFB drops to 80% of VREF (UV) or

exceeds 116% of VREF (OV), PG is pulled low.

Once VFB rises back to its nominal voltage

window (rises to 92.5% of VREF for UV, drops to

102.5% of VREF for OV), PG goes high again.

If the input supply fails to power the MP2276,

PG is pulled low, even though it is tied to an

external DC source through a pull-up resistor.

The relationship between the PG voltage and

the pull-up current is shown in Figure 5.

Figure 5: PG Clamped Voltage vs. Pull-Up

Current

Enable (EN) Configuration

The MP2276 turns on when EN goes high. The

MP2276 turns off when EN goes low. EN

cannot be left floating for proper operation. EN

can be driven by an analog or digital control

logic signal to enable or disable the MP2276.

EN is clamped internally using a 4V series

Zener diode (see Figure 6). Connect the EN

input through a pull-up resistor to VIN to limit

the EN input current to

less than 100μA to

prevent damage to the Zener diode. For

example, if connecting a 300k

Ω pull-up resistor

to 16VIN, then IZener = (16V - 4V) / 300kΩ =

40µA.

The MP2276 provides accurate EN thresholds,

so a resistor divider from VIN to AGND can be

used to program the input voltage at which the

MP2276

enabled.

This

highly

recommended for applications where there is

no dedicated EN control logic signal to avoid

possible UVLO bouncing during power-up and

power-down. The resistor divider values can be

determined with Equation (5):

DOWN

START

VIH







)

(

(5)

Where VIHEN is 1.21V, typically. RUP and RDOWN

should be chosen to limit the EN input current

below

100μA.

Logic

GND

1.7kΩ

Figure 6: Zener Diode between EN and GND

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