Datasheet

Figure 7 : For higher currents, outputscan be paralleled. Take care to parallel channel1 with channel4
and channel2 with channel 3.
APPLICATION INFORMATION (Refer to the block diagram)
1.1. POWER OUTPUT STAGE
TheL298integratestwo power outputstages(A;B).
The power output stage is a bridge configuration
and its outputs can drive an inductive load in com-
monor differenzialmode, dependingon the state of
the inputs. The current that flows through the load
comes out from the bridge at the sense output: an
externalresistor (R
SA
;R
SB
.) allows to detect the in-
tensityof this current.
1.2. INPUT STAGE
Each bridge is driven by means of four gatesthe in-
put of which are In1 ; In2 ; EnA and In3 ; In4 ; EnB.
The In inputssetthe bridge statewhen The Eninput
ishigh; alowstateof theEninput inhibitsthebridge.
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.Whenthe largeca-
pacitor of the power supply is too far from the IC, a
second smaller one must be foreseen near the
L298.
The sense resistor, not of a wire wound type, must
be groundednearthe negative pole of Vs that must
be near the GND pin of the I.C.
Eachinput must be connectedto the source of the
driving signals by means of a very short path.
Turn-On and Turn-Off : Beforeto Turn-ON the Sup-
plyVoltageandbeforeto Turnit OFF,theEnablein-
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 diodesD1 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 outputvoltagecanbe usedto control the
current amplitude by choppingthe inputs, or to pro-
vide overcurrent protection byswitching low the en-
able input.
The brake function (Fast motor stop) requires that
the Absolute Maximum Rating of 2 Amps must
neverbe 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).
An external bridge of diodes are required when in-
ductive loads are driven and when the inputs of the
IC arechopped; Shottkydiodes wouldbepreferred.
L298
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