16

SLDM-06D1Ax

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16. ANALOG ON/OFF

The SLDM-06D1Ax power modules feature an On/Off pin for remote On/Off operation. Two On/Off logic options are available. In the Positive

Logic On/Off option, (device code suffix “0” – see Ordering Information), the module turns ON during a logic High on the On/Off pin and turns

OFF during a logic Low. With the Negative Logic On/Off option, (device code suffix “L” – see Ordering Information), the module turns OFF during

logic High and ON during logic Low. The On/Off signal should be always referenced to ground. For either On/Off logic option, leaving the On/Off

pin disconnected will turn the module ON when input voltage is present.

For positive logic modules, the circuit configuration for using the On/Off pin is shown in Figure 39. When the external transistor Q2 is in the OFF

state, the internal transistor Q7 is turned ON, which turn Q3 OFF which keeps Q6 OFF and Q5 OFF. This allows the internal PWM #Enable

signal to be pulled up by the internal 3.3V, thus turning the module ON. When transistor Q2 is turned ON, the On/Off pin is pulled low, which

turns Q7 OFF which turns Q3, Q6 and Q5 ON and the internal PWM #Enable signal is pulled low and the module is OFF. A suggested value for

Rpullup is 20k.

For negative logic On/Off modules, the circuit configuration is shown in Fig. 40. The On/Off pin should be pulled high with an external pull-up

resistor (suggested value for the 3V to 14V input range is 20Kohms). When transistor Q2 is in the OFF state, the On/Off pin is pulled high,

transistor Q3 is turned ON. This turns Q6 ON, followed by Q5 turning ON which pulls the internal ENABLE low and the module is OFF. To turn

the module ON, Q2 is turned ON pulling the On/Off pin low, turning transistor Q3 OFF, which keeps Q6 and Q5 OFF resulting in the PWM Enable

pin going high.

Figure 39

Circuit configuration for using positive On/Off logic

Figure 40

Circuit configuration for using negative On/Off logic

20K

Rpullup

I

20K

ON/OFF

+

20K

3.3V

470

VIN

20K

Q7

20K

100pF

4.7K

ENABLE

100K

Module

47K

Q2

+VIN

ENABLE

470

4.7K

+VIN

20K

100K

2K

100pF

_

47K

GND

Q6

20K

Q2

+

Module

V

Rpullup

Q3

ON/OFF

20K

I

ON/OFF

3.3V

Q5

20K