L6204D(1994) データシートの表示（PDF） - STMicroelectronics

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L6204D
(Rev.:1994)

DMOS DUAL FULL BRIDGE DRIVER

STMicroelectronics 

L6204

CIRCUIT DESCRIPTION

L6204 is a dual full bridge IC designed to drive

DC motors, stepper motors and other inductive

loads. Each bridge has 4 power DMOS transistor

with RDSon = 1.2Ω and the relative protection and

control circuitry. (see fig. 3)

The 4 half bridges can be controlled independently

by means of the 4 inputs IN!, IN2, IN3, IN4 and 2

enable inputs ENABLE1 and ENABLE2.

External connections are provided so that sensing

resistors can be added for constant current chop-

per applications.

LOGIC DRIVE (*)

INPUTS

IN1

IN3

EN1=EN2=H L

L

H

H

EN1=EN2=L X

IN2 OUTPUT MOSFETS

IN4

L Sink 1, Sink 2

H Sink 1, Source 2

L Source 1, Sink 2

H Source 1, Source 2

X All transistor turned

OFF

L = Low H = High X = Don’t care

(*) True table for the two full bridges

CROSS CONDUCTION

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. 1). 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

(see fig. 2).

Figure 1: Intrinsic Structures in the POWER

MOS Transistors

Figure 2: Current Typical Spikes on the Sensing Pin

TRANSISTOR OPERATION

ON STATE

When one of the POWER DMOS transistors is ON

it can be considered as a resistor RDS(ON) = 1.2Ω at

a junction temperature of 25°C.

In this condition the dissipated power is given by :

PON = RDS(ON) ⋅ IDS2

The low RDS(ON) of the Multipower-BCD process

can provide high currents with low power dissipa-

tion.

OFF STATE

When one of the POWER DMOS transistor is

OFF the VDS voltage is equal to the supply volt-

age and only the leakage current IDSS flows. The

power dissipation during this period is given by :

POFF = VS ⋅ IDSS

TRANSITIONS

Like all MOS power transistors the DMOS

POWER transistors have as intrinsic diode be-

tween their source and drain that can operate as

a fast freewheeling diode in switched mode appli-

cations. During recirculation with the ENABLE in-

put high, the voltage drop across the transistor is

RDS(ON) . ID and when the voltage reaches the di-

ode voltage it is clamped to its characteristic.

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 and current waveforms in the application.

Ptrans. = IDS(t) ⋅ VDS(t)

BOOTSTRAP CAPACITORS

To ensure the correct driving of high side drivers

4/10

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