L6219DS データシートの表示（PDF） - Allegro MicroSystems

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L6219DS

DUAL FULL-BRIDGE PWM MOTOR DRIVER

Allegro MicroSystems 

L6219DS

DUAL FULL-BRIDGE

MOTOR DRIVER

APPLICATIONS INFORMATION

PWM CURRENT CONTROL

The L6219DS dual bridge is designed

to drive both windings of a bipolar stepper

motor. Output current is sensed and con-

trolled independently in each bridge by an

external sense resistor (RS), internal com-

parator, and monostable multivibrator.

PWM OUTPUT CURRENT WAVE FORM

V PHASE

When the bridge is turned on, current

increases in the motor winding and it is

sensed by the external sense resistor until

the sense voltage (VCOMPIN) reaches the level

set at the comparator’s input:

ITRIP = VREF/10 RS

The comparator then triggers the

monostable which turns off the source driver

of the bridge. The actual load current peak

will be slightly higher than the trip point

(especially for low-inductance loads) be-

cause of the internal logic and switching

delays. This delay (td) is typically 2 µs. After

turn-off, the motor current decays, circulating

through the ground-clamp diode and sink

transistor. The source driver’s off time (and

therefore the magnitude of the current

decrease) is determined by the monostable’s

external RC timing components, where

toff = RTCT within the range of 20 kΩ to

100 kΩ and 100 pF to 1000 pF.

+

I OUT 0

–

I TRIP

td

toff

Dwg. WM-003-1A

LOAD CURRENT PATHS

V

BB

When the source driver is re-enabled,

the winding current (the sense voltage) is

again allowed to rise to the comparator’s

threshold. This cycle repeats itself, maintain-

ing the average motor winding current at the

desired level.

Loads with high distributed capaci-

tances may result in high turn-on current

peaks. This peak (appearing across R )

S

will attempt to trip the comparator, resulting

in erroneous current control or high-fre-

quency oscillations. An external RCCC time

delay should be used to further delay the

action of the comparator. Depending on load

type, many applications will not require these

external components (SENSE connected to

COMP IN).

BRIDGE ON

RS

SOURCE OFF

ALL OFF

Dwg. EP-006-1

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

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