PRELIMINARY DATASHEET

May, 2000

10

PRELIMINARY

ML4435

COAST

When CVCO (pin 20) is pulled below 1.5V the output

drivers LA, LB, LC and

HA, HB, and HC are turned off.

The COAST function shuts all power off from the motor

allowing it to coast to a stop. The COAST function in (pin

20) is configured as shown in Figure 13 and can be driven

by a switch to ground or open collector to ground also

shown in Figure 13.

Figure 14a. ML4435 Typical Application

UNDER VOLTAGE PROTECTION

Undervoltage protection is used to protect the 3 phase

bridge power stage from a low VCC condition. Undervolt-

age is triggered at VCC of 9.2V or under. Undervoltage

also turns off all output drivers LA, LB, LC,

HA, HB, and

HC. The comparator that triggers undervoltage protection

has 500mV of hystersis.

INTERFACING THE OUTPUT DRIVERS TO THE 3

PHASE BRIDGE POWER STAGE

The most flexible configuration is to use high side drivers

to control N-Channel MOSFETs (or IGBTs) allowing appli-

cations from less than 12V up to 170V. Figure 14a shows

the ML4435 and all the support circuitry in a typical

application. Figure 14b shows a power stage using the

IR2118 high side drivers from International Rectifier and

high voltage MOSFETs.

FUNCTIONAL DESCRIPTION

2

3

4

5

6

9

0

2

3

4

5

6

9

0

2

3

4

5

6

9

20

2

22

23

24

25

26

20

9

6

5

4

3

2

C2

2V

0.

F

C

4F

C5

0.33 F

C4

0F

C

.033 F

C

.F

R5

0k

R6

TP 2

S FB

200k

C9

.0

F

C0

TP 5 LIMIT

RUN

N.C.

SW

SW4PDT

COAST

N.C.

N.C.

IDC 26

P

N.C.

N.C.

N.C.

2V

N.C.

N.C.

N.C.

00 F

R 0

k

R 2

k

R9

k

R

k

R

90.9k

R

k

TP

SPEED SET

TP 3 TACH

TP 0 ISENSE

R2

00k

R6

0k

R4

20k

C3

2200 F

R3

k

ML4435

ISENSE

TACH

S COMP

RVCO

S SET

RT

HA

HB

HC

VCC

CVCO

I LIMIT

S FB

ND

FB C

FB B

FB A

LC

LB

LA

.5V

3. 5V

2V

+

–

COMP

CVCO

COAST

20

Figure 13. Coast Control