Fixed Frequency High Current Synchronous Buck Regulator

With Fault Warnings and Power OK

A8672

6

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Characteristics

Symbol

Test Conditions

Min.

Typ.

Max.

Unit

Power OK

Power Good Threshold (Rising)

Feedback voltage relative to reference voltage,

POK = high

92

95

98

%

Power Good Threshold (Falling)

Feedback voltage relative to reference voltage,

POK = high

107

110

113

%

Power Good Hysteresis

–

5

–

%

POK Rising Delay

–

90

–

µs

POK Output Voltage

–

–

500

mV

POK Leakage Current

–

–

1

μA

Fault Reporting

¯F¯¯A¯U¯¯L¯¯T¯ Overtemperature

Temperature rising

–

140

–

°C

¯F¯¯A¯U¯¯L¯¯T¯ Overtemperature Hysteresis

–

20

–

°C

¯F¯¯A¯U¯¯L¯¯T¯ Output Voltage

–

–

500

mV

¯F¯¯A¯U¯¯L¯¯T¯ Leakage

–

–

1

µA

Protection

Undervoltage Threshold (Falling)

Feedback voltage relative to reference voltage

–

75

–

%

Undervoltage Hysteresis

–

5

–

%

Overvoltage Threshold (Rising)

Feedback voltage relative to reference voltage

115

120

125

%

Overvoltage Hysteresis

–

5

–

%

Valley Current Limit Voltage Range

1.0

–

2.75

V

Valley Current Limit

ILIM resistor = 169 kΩ

3.0

4.0

5.0

A

ILIM resistor = 249 kΩ

6.0

8.0

10.0

A

Either valley current limit or overvoltage

condition reached

–

50

–

µs

–

10

–

ms

events

-

1.2

-

ms

Pulse-by-Pulse Negative Valley

Current Limit

FCCM selected

–2.4

–1.9

–1.4

A

FB Overvoltage Duration

High-side MOSFET off, low-side MOSFET on

–

50

–

μs

High-Side MOSFET Protection Current

LX node short-circuited to GND

–

25

–

A

High-Side MOSFET Protection Voltage

LX node short-circuited to GND

450

650

850

mV

VDD Undervoltage Lockout (Rising)

–

4.2

4.45

V

–

300

–

mV

Thermal Shutdown Threshold

Temperature rising

–

165

–

°C

Thermal Shutdown Hysteresis

–

15

–

°C

1

2

Positive current is into the node or pin, negative current is out of the node or pin.