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AN1762 APPLICATION NOTE

3.9 Input Logic pins

IN1A, IN2A, IN1B, IN2B are CMOS/TTL compatible logic input pins. The input comparator has been realized with hys-

teresis to ensure the required noise immunity. Typical values for turn-on and turn-off thresholds are Vth,ON = 1.8V and

Vth,OFF = 1.3V. Pins are ESD protected (see Figure 12) (2kV human-body electro-static discharge), and can be directly

connected to the logic outputs of a µC; a series resistor is generally not recommended, as it could help inducted noise

to disturb the inputs. All logic pins enforce a specific behavior and cannot be left unconnected.

Figure 12. Logic input pins.

3.10 EN pins

The

ENA, ENB pins are, actually, bi-directional: as an input, with a comparator similar to the other logic input pins (TTL/

CMOS with hysteresis), they control the state of the PowerDMOS. When each of the two pins is at a low logic level,

all the PowerDMOS of the corresponding H-bridge (A or B) are turned off. In L6205 and L6207 the EN pins are also

connected to the two corresponding open drain outputs of the protection circuits that will pull the pins to GND if over

current in the corresponding H-bridge or over temperature conditions exist. In L6206 the open drain outputs are on

separate pins, OCDA and OCDB, allowing easier external diagnostics and overcurrent management. For this reason,

with L6205 and L6207 (and L6206 if EN pins are connected to DIAG pins) EN pins must be driven through a series

resistor of 2.2k

Ω minimum (for 5V logic), to allow the voltage at the pin to be pulled below the turn-off threshold.

A capacitor (CEN in Figure 13) connected between each EN pin and GND is also recommended, to reduce the r.m.s.

value of the output current when overcurrent conditions persist (see

Over Current Protection section). EN pin must

not be left unconnected.

Figure 13. ENA and ENB input pins.

D01IN1329

ESD

PROTECTION

PUSH-PULL

OUTPUT

REN

CEN

ENA or ENB

OCDA or OCDB

PUSH-PULL

OUTPUT

REN

CEN

ENA or ENB

L6205, L6207

L6206

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