L6219L-S24-R datasheet(5/9 Pages) UTC

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L6219

LINEAR INTEGRATED CIRCUIT

UNISONIC TECHNOLOGIES CO., LTD

5 of 9

www.unisonic.com.tw

QW-R109-005.D



APPLI CAT I ON I N FORM AT I ON

Logic Control Of Output Current

Two logic level inputs (I0 and I1) allow digital selection of the motor winding current at 100%, 67%, 33%, or 0% of

the maximum level per the table. The 0% output current condition turns off all drivers in the bridge and can be used

as an OUTPUT ENABLE function.

These logic level inputs greatly enhance the implementation of

μP-controlled drive formats.

During half-step operations, the I0 and I1 allow the

μP to control the motor at a constant torque between all

positions in an eight-step sequence. This is accomplished by digitally selection 100% drive current when only one

phase is on and 67% drive current when two phases are on. Logic highs on both I0 and I1 turn off all drivers to allow

rapid current decay when switching phases. This helps to ensure proper motor operation at high step rates.

The logic control inputs can also be used to select a reduced current level (and reduced power dissipation) for

“hold” conditions and/or increased current (and available torque )for start-up conditions.

Current-Control Truth Table

Output Current

VREF/10RS=ITRIP

VREF/15RS=2/3 ITRIP

VREF/30RS=1/3 ITRIP

General

The PHASE input to each bridge determines the direction motor winding current flows. An internally generated

dead time (approximately 2

μs) prevents crossover currents that can occur when switching the PHASE input.

All four drivers in the bridge output can be tuned off between steps (I0=I1

≥2.4V) resulting in a fast current decay

through the internal output clamp and flyback diodes. The fast current decay is desirable in half-step and high-speed

applications. The PHASE,I0, and I1 inputs float high.

Varying the reference voltage (VREF) provides continuous control of the peak load current for microstepping

applications.

Thermal protection circuitry turns off all drivers when the junction temperature reaches +170

C. It is only intended

to protect the device from failures due to excessive junction temperature and should not imply that output short

circuits are permitted. The output drivers are re-enabled when the junction temperature cools to +145

C.

The UTC L6219 output drivers are optimized for low output saturation voltages-less than 1.8V total (source plus

sink) at 500mA.Under normal operating conditions, when combined with the excellent thermal properties of the

batwing package design, this allows continuous operation of both bridges simultaneously at 500mA.

Current Sensing

To minimize current sensing inaccuracies caused by ground trace IR drops, each current-sensing resistor should

have a separate return to the ground terminal of the device. For low-value sense resistors, the IR drops in the PCB

can be significant and should be taken into account. The use of sockets should be avoided as their contact

resistance can cause variations in the effective value of RS.

Generally, larger values of RS reduce the aforementioned effects but can result in excessive heating and power

loss in the sense resistor. The selected value of RS should not cause the absolute maximum voltage rating of 1.5 V,

for the SENSE terminal, to be exceeded. The recommended value of RS is in the range of:

RS=0.75/ITRIP(max) ±50% .

If desired, the reference input voltage can be filtered by placing a capacitor from REFIN to ground. The ground

return for this capacitor as well as the bottom of any resistor divider used should be independent of the high-current

power-ground trace to avoid changes in REFIN due to IR drops.

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