CIRCUIT DESCRIPTION

The L6201/1PS/2/3 is a monolithic full bridge

switching motor driver realized in the new Mul-

tipower-BCD technology which allows the integra-

tion of multiple, isolated DMOS power transistors

plus mixed CMOS/bipolar control circuits. In this

way it has been possible to make all the control

inputs TTL, CMOS and

µC compatible and elimi-

nate the necessity of external MOS drive compo-

nents. The Logic Drive is shown in table 1.

Table 1

Inputs

Output Mosfets (*)

IN1

IN2

L

L

H

H

L

H

L

H

Sink 1, Sink 2

Sink 1, Source 2

Source 1, Sink 2

Source 1, Source 2

X

X

All transistors turned oFF

L = Low

H = High

X = DON’t care

(*) Numbers referred to INPUT1 or INPUT2 controlled output stages

Although the device guarantees the absence of

cross-conduction, the presence of the intrinsic di-

odes in the POWER DMOS structure causes the

generation of current spikes on the sensing termi-

nals. This is due to charge-discharge phenomena

in the capacitors C1 & C2 associated with the

drain source junctions (fig. 14). When the output

switches from high to low, a current spike is gen-

erated associated with the capacitor C1. On the

low-to-high transition a spike of the same polarity

is generated by C2, preceded by a spike of the

opposite polarity due to the charging of the input

capacity of the lower POWER DMOS transistor

(fig. 15).

TRANSISTOR OPERATION

ON State

When one of the POWER DMOS transistor is ON

throughout the recommended operating range. In

this condition the dissipated power is given by :

can provide high currents with low power dissipa-

tion.

OFF State

When one of the POWER DMOS transistor is

power dissipation during this period is given by :

The power dissipation is very low and is negligible

in comparison to that dissipated in the ON

STATE.

Transitions

As already seen above the transistors have an in-

trinsic diode between their source and drain that

can operate as a fast freewheeling diode in

switched mode applications. During recirculation

with the ENABLE input high, the voltage drop

reaches the diode forward voltage it is clamped.

When the ENABLE input is low, the POWER

MOS is OFF and the diode carries all of the recir-

culation current. The power dissipated in the tran-

sitional times in the cycle depends upon the volt-

age-current waveforms and in the driving mode.

(see Fig. 7ab and Fig. 8abc).

Figure 14: Intrinsic Structures in the POWER

DMOS Transistors

Figure 15: Current Typical Spikes on the Sens-

ing Pin

L6201 - L6202 - L6203

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