International Rrectifier IR3870MBF User Manual

PD-97392

SupIRBuck

10A HIGHLY INTEGRATED

IR3870MBF

WIDE-INPUT VOLTAGE, SYNCHRONOUS BUCK REGULATOR

Features

• Input Voltage Range: 3V to 26V

• Output Voltage Range: 0.5V to 12V

• Continuous 10A Load Capability

• Constant On-Time control

• Excellent Efficiency at very low output current levels

• Gate drive charge pump option to maximize efficiency at higher output current levels

• Compensation Loop not Required

• Programmable switching frequency, soft start, and over current protection

• Power Good Output

• Precision Voltage Reference (0.5V, +/-1%)

• Enable Input with Voltage Monitoring Capability

• Pre-bias Start Up

• Under/Over Voltage Fault Protection

• Ultra small, low profile 5 x 6mm QFN Package

• Lead-free, halogen-free and RoHS compliant

Applications

• Notebook and desktop computers

• Game consoles

• Consumer electronics - STB, LCD TV, Printers

• General purpose POL DC-DC Converters

Description

The IR3870M SupIRBuck

fully integrated and highly efficient DC/DC voltage regulator. The onboard constant on time hysteretic controller and MOSFETs make IR3870 a space-efficient solution that delivers up to 10A of precisely controlled output voltage in 60°C ambient temperature applications without airflow.

Programmable switching frequency, soft start, and over current protection allows for a very flexible solution suitable for many different applications. The combination of the gate drive charge pump option and constant on time control allow efficiency optimization in the whole output current range, making this device an ideal choice for battery powered applications.

Additional features include pre-bias startup, very precise 0.5V reference, over/under voltage shut down, power good output, and enable input with voltage monitoring capability.

is an easy-to-use,

1/27/2010

Typical Notebook Application Circuit Diagram

IR3870MBF

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND unless otherwise specified)

• VIN ……………………………………………………. 30V

• VCC ……………….….………………………………. 3.9V

• PVCC ……………….….…………….……..………… 7.5V

• Boot ……………………………………..……….….. 40V

• PHASE …………………………………………..…….. -0.3V to 30V(DC), -5V(100ns)

• Boot to PHASE…..…………………………….…..…… 7.5V

• FF ………………………………………….………… 30V

• PGND to GND ……………...…………………………. -0.3V to +0.3V

• All other pins ……………...…………………………… 3.9V

• Storage Temperature Range ..................................... -65°C To 150°C

• Junction Temperature Range .................................... -10°C To 150°C

• ESD Classification …………………………….……… JEDEC Class 1C

• Moisture sensitivity level………………...…………….. JEDEC Level 3@260 °C

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the

device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications are not implied.

PACKAGE INFORMATION

5mm x 6mm POWER QFN

PCBJ

W/C35θ

W/C2θ

ORDERING INFORMATION

PKG DESIG

PACKAGE

DESCRIPTION

IR3870MTRPbF

PIN COUNT

PARTS PER

REEL

4000

75023IR3870MTR1PbFM

Block Diagram

IR3870MBF

Pin Description

DESCRIPTIONI/O LEVELNUMBERNAME

No connection1NC

Connecting resistor to PHASE pin sets over current trip point2ISET

Power good – pull up to 5V5V3PGOOD

Bias return and signal referenceReference4,17GND

Inverting pin of PWM comparator and OVP/PGood sense3.3V5FB

Set soft start slew-rate with a capacitor to GND 3.3V6SS

No connection7NC

Internal bias supply3.3V8VCC

Charge pump output0.75V9CPO

Gate drive supply5V10PVCC

Power returnReference11PGND

Phase node (or switching node) of MOSFET half bridgeVIN12PHASE

IR3870MBF

Input voltage for the system.VIN13VIN

14BOOT

VIN +PVCC

VIN15FF

Bootstrapped gate drive supply – connect a capacitor to PHASE

Input voltage feed forward – sets on-time with a resistor to VIN

Enable – turns device on or off5V16EN

IR3870MBF

Recommended Operating Conditions

Symbol Definition Min Max Units

VIN Input Voltage 3 26* VCC Supply Voltage 3 3.6 Boot to

Supply Voltage 7.0 PHASE V

Output Voltage 0.5 12

OUT

Output Current 0 10 A

OUT

Fs Switching Frequency 1000 kHz

* Note: PHASE pin must not exceed 30V.

Electrical Specifications

Unless otherwise specified, these specification apply over VIN = 12V, PVCC = 7VDC, 0oC ≤ TJ≤ 125oC.

PARAMETER NOTE TEST CONDITION MIN TYP MAX UNIT

BIAS SUPPLIES

VCC Turn-on Threshold 3 V

VCC Turn-off Threshold

VCC Threshold Hysteresis

PVCC Turn-on Threshold

PVCC Turn-off Threshold

PVCC Threshold Hysteresis

VCC Shutdown Current VCC Operating Current RFF = 180k, EN = HIGH 1.2 mA PVCC Operating Current RFF = 180k,

PVCC Shutdown Current EN=LOW 20 60 FF Shutdown Current EN=LOW 0.1 2

VIN Shutdown Current EN=LOW 0 1 PHASE Shutdown Current EN=LOW 0.25 2

CONTROL LOOP

Reference Accuracy, V

On-Time Accuracy

Min Off Time

Soft-Start Current

FAULT PROTECTION ISET pin output current 18 20 22

Under Voltage Threshold Falling VFB & monitor PGOOD 0.37 0.4 0.43 V Under Voltage Hysteresis Rising VFB 7.5 mV Over Voltage Threshold Rising VFB & monitor PGOOD 0.56 0.6 0.64 V Over Voltage Hysteresis 1 Rising VFB 7.5 mV PGOOD Delay Threshold (VSS) 0.6 V

REF

EN=LOW 30 60

EN = HIGH, Fs = 500kHz

= 180 k, TJ = 650C

EN = HIGH

2.65 V

60 mV

3.05 V

2.65 V

60 mV

8 mA

0.495 0.5 0.505 V

280 300 320 ns

300 ns

8 10 12

μA

μA μA μA μA

μA

IR3870MBF

Electrical Specifications (continued)

Unless otherwise specified, these specification apply over VIN = 12V, PVCC = 7VDC, 0oC ≤ TJ ≤ 125oC.

PARAMETER NOTE TEST CONDITION MIN TYP MAX UNIT

GATE DRIVE

Dead time 1 Monitor body diode conduction on

PHASE pin UPPER MOSFET Static Drain-to-Source On-

PVCC =5V, ID =10A, TJ =25oC 14.7 m