IR3220.pdf

An integrated motor drive power IC is space and power efficient with

an architecture scalable to higher current levels. A fully protected

dual high-side MOSFET power switch has an entire H-bridge control.

With two additional low-side MOSFETs, it limits the inrush current to a

dc motor, drives it in both directions, and offers a braking mode.

otors play a key role in the increasing com-

fort and convenience in today’s vehicles,

providing functions from adjusting seats

or headlamps to lifting windows and mov-

ing sunroof doors. However, making the

motor easy to control, safe, and reliable in an automotive

system in a cost-effective fashion isn’t an easy task. Over

half of the motors in today’s vehicles (by function

alone—many have multiple uses) conduct less than an av-

erage of 6A. Automotive applications for an H-bridge mo-

tor drive include any brush type dc motor, such as seat and

windshield wiper motors, and many other body electron-

ics applications.

A new power management IC, the IR3220, implements

a cost-effective motor drive for automotive applications. It

handles switching, reversing, and protection to save cost,

cut motor drive space, and simplify electrical and thermal

design. This power IC integrates the H-bridge control and

protection functions with two high-side (HS) MOSFETs.

Completing the H-bridge are two low-side (LS) MOSFET

switches in separate packages. The IC provides overcurrent

protection against short circuits in the associated motor. It

also includes overtemperature shutdown, in case the mo-

tor encounters problems. Also included is a soft-start (SS)

circuit that limits inrush current and produces a smooth

and stress-free ramp-up. Additional safety features include

undervoltage lockout, overvoltage protection from inte-

grated active clamping circuitry, non-braking mode, and

diagnostic feedback.

HS switches are integrated in the controller to provide

ease of drive, directional capability, and H-bridge protec-

tion. LS MOSFETs are separate to provide flexibility by of-

fering the high-frequency switching ability for the SS func-

tion. Fig. 1 , on page 18, shows the dc motor drive architec-

ture. The control circuit and HS drivers are in a surface-

mount SO20 package. Two LS MOSFETs are each in SO8

Power Electronics Technology April 2002

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yy R an

aand y F

y Fr an

aank , International Rectifier, El Segundo, Calif.; and Xa vier de F

vier de Fr u t os, International Rectifier, Aix En Provence, France

packages. The combination provides forward, reverse, and

braking for up to an 80W dc motor.

diagonal commands among the four MOSFETs.

• The normal quiescent state of the two LS MOSFETs

is ON. To avoid conflicts, the shoot-through preven-

tion circuit generates the proper LS command.

• An internal SS circuit sends a PWM signal to both

LS MOSFETs without considering the H-bridge di-

rection. Therefore, the PWM circuit is almost inde-

pendent and offers flexibility for extended operations

(controlling the speed or the torque.)

Each principle provides inherent safety for the H-bridge

topology. Control functions such as undervoltage lockout,

non-braking mode, temperature protection, and the diag-

nostic feedback are contained in the “IC logic control” func-

tional block in Fig. 3 , on page 18.

The two HS switches have an R DS(on) =12 m

inciples

Two of the four transistors produce the H-bridge output.

One HS and the diagonally opposite LS conduct at one

time, and then the other HS and LS switches conduct the

next time. Only one set of output transistors or one leg

should conduct current at a time. If both sets try to con-

duct at the same time, you get a shoot-through condition.

If that occurs, the power IC can be destroyed. The IR3220

provides a novel and fail-safe approach to protection against

shoot-through ( Fig. 2 , on page 18).

The IR3220 architecture relies on four basic principles:

• Each leg of the H-bridge is totally independent of

the other leg.

• Each leg contains separate current protection and a

shoot-through prevention circuit that eliminates

esign Principles

inciples

(typical)

and can handle I DC =6A at 85°C. The control circuit can

operate with V CC =5.5V to 35V and provide I shutdown =30A and

T shutdown = 165°C.

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Power Electronics Technology April 2002

B y

aan

y F

aan

vier de F

Design P

esign P

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Power Electronics Technology April 2002

MOTOR DRIVE

3 3. Circuitry in the IR3220 that drives and protects the integrated

HS switches and separate the LS switches. Control functions such as

undervoltage lockout, non-braking mode, temperature protection,

and the diagnostic feedback are contained here.

iig..... 3

3 3

iig..... 1.

1. IR3220 H-bridge motor drive architecture.

tion

Fig. 4 , on page 20, shows the shoot-

through prevention circuit details.

Each leg’s shoot-through protection

takes advantage of the switching time

difference between the LS MOSFET

and the HS switch. Because of its

charge pump circuit, the HS switch has

slow turn-on/turn-off times com-

ot-Thr

hhrough P

ough Prot

ootec

eection

tion

pared with the direct drive of the LS

MOSFET. Therefore, when IN 1(2)

goes high, the complemented signal

turns off the LS MOSFET while the

charge pump circuit hasn’t turned ON

the HS switch. When IN 1(2) goes low,

the HS switch turns-off slowly and the

LS MOSFET doesn’t turn on again un-

til its V ds decreases to 2V (back to its

2 2. Basic H-bridge operation: (a) One pair of

transistors drive the load; (b) the other switches in.

2 2

Power Electronics Technology April 2002

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Fig

iig

Fig

Sho

hho

hhoot-T

ot-T

hhr

ough P

oot

eec

Fig

iig

iig..... 2

MOTOR DRIVE

iig .. ... 4

4 4. IR3220’s shoot-through prevention circuit.

iig .. ... 5

5 5. Soft-start sequence circuit.

quiescent ON state). This technique provides a self-adap-

tive deadtime circuit with no time-dependent elements.

The core of the shoot-through circuit consists of an RS

flip-flop and a voltage comparator. This configuration

stores the request for HS turn-on and then resets it when

it’s fully OFF (i.e., V M1 –V Gnd ] < 2V). The LS driver features

a low consumption “Sleep Mode Pull-up” for the quies-

cent ON state. Although the PWM signal is sent to both LS

MOSFETs at the same time, the leg with the IN input at 0V

is the only one that cycles its LS MOSFET.

The SS sequence ( Fig. 5 ) limits inrush current and pro-

vides a smooth and low-stress speed ramp-up. This block

generates the PWM signal for switching start-up. It con-

sists of a 20 kHz oscillator, voltage comparator, and RC

charge/discharge circuit. It compares a 3V symmetrical

sawtooth with the SS pin voltage and the PWM signal sent

to the LS MOSFETs. The sawtooth goes from 1V to 4V,

so the SS pin produces a duty cycle from 0% (SS < 1V) up

to 100% (SS > 4V). The SS pin is normally the central point

of an RC network powered by the V RC pin. It implements

Power Electronics Technology April 2002

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i ig

F ig

4 4

i ig

F ig

5 5

MOTOR DRIVE

LS MOSFET. Thus, the switching

waveform goes from 0% to 100% duty

cycle, offering a low-stress ramp-up to

its load. Fig. 6 , on page 22, shows an

example of SS sequence waveforms.

xample

The layout in Photo 1 corresponds to

a 6A dc motor drive on a p. c. board

less than 1 in.². The IRF7484 n-chan-

nel MOSFET was developed for the

companion LS switches. This 40V, 8-

tion Example

xample

o 2. A window-lift dc motor with an IR3220

reference kit on the housing.

o 2

o 1. A 6A H-bridge control circuit in a

25 mm × 21 mm footprint.

o 1

(max) MOSFET

is housed in an SO8 package. The 10

a discharge circuit to reset and hold

the SS pin at a low level while the H-

bridge is off.

Setting one of the IN 1(2) pins high

activates the corresponding leg of the

H-bridge (the HS switch turns on and

the LS MOSFET turns off ), releasing

the discharge circuit. The SS voltage

increases slowly, resulting in a smooth

duty-cycle variation at the gate of the

Ω

(maximum) of the integrated HS

switch make this an efficient motor

drive for 6A applications.

The IR3220 reference design has

four power MOSFETs with less than

22m

on-resistance in an H-bridge

topology. The IR3220 can drive low-

cost, cable-driven window-lift systems

( Photos 2 and 3) .

o 3. A TO-220/5-pin intelligent power

switch (IPS) package (left) compared to the

IR3220 reference kit (right). The IPS is a 25-m Ω

high side switch with integrated circuitry.

o 3

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Power Electronics Technology April 2002

Applic

pplic

pplication E

tion E

Phot

hot

hoto 2

hot

Phot

hot

hoto 1

o 1

(typical), 10 m

of the LS switch and the 12 m

P ho

hho

hhot o 3

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