L298 Просмотр технического описания (PDF) - STMicroelectronics

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L298

DUAL FULL-BRIDGE DRIVER

STMicroelectronics 

L298

Figure 7 : For higher currents, outputs can be paralleled. Take care to parallel channel 1 with channel 4

and channel 2 with channel 3.

APPLICATION INFORMATION (Refer to the block diagram)

1.1. POWER OUTPUT STAGE

TheL298integratestwo poweroutputstages(A ; B).

The power output stage is a bridge configuration

and its outputs can drive an inductive load in com-

mon or differenzialmode, dependingon the state of

the inputs. The current that flows through the load

comes out from the bridge at the sense output : an

external resistor (RSA ; RSB.) allows to detect the in-

tensity of this current.

1.2. INPUT STAGE

Each bridge is driven by means of four gates the in-

put of which are In1 ; In2 ; EnA and In3 ; In4 ; EnB.

The In inputs set the bridge state when The En input

is high ; a lowstate of the En inputinhibitsthe bridge.

All the inputs are TTL compatible.

2. SUGGESTIONS

A non inductive capacitor, usually of 100 nF, must

be foreseen between both Vs and Vss, to ground,

as near as possible to GND pin. When the large ca-

pacitor of the power supply is too far from the IC, a

second smaller one must be foreseen near the

L298.

Each input must be connected to the source of the

driving signals by means of a very short path.

Turn-On and Turn-Off : Before to Turn-ON the Sup-

ply Voltageand beforeto Turnit OFF, the Enablein-

put must be driven to the Low state.

3. APPLICATIONS

Fig 6 shows a bidirectional DC motor control Sche-

matic Diagram for which only one bridge is needed.

The external bridge of diodes D1 to D4 is made by

four fast recovery elements (trr ≤ 200 nsec) that

must be chosen of a VF as low as possible at the

worst case of the load current.

The sense outputvoltage can be used to control the

current amplitude by chopping the inputs, or to pro-

vide overcurrent protection by switching low the en-

able input.

The brake function (Fast motor stop) requires that

the Absolute Maximum Rating of 2 Amps must

never be overcome.

When the repetitive peak current needed from the

load is higher than 2 Amps, a paralleled configura-

tion can be chosen (See Fig.7).

The sense resistor, not of a wire wound type, must

be grounded near the negative pole of Vs that must

be near the GND pin of the I.C.

An external bridge of diodes are required when in-

ductive loads are driven and when the inputs of the

IC are chopped; Shottkydiodeswould bepreferred.

7/13

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