Application information

GS-R12F

6/12

4

Application information

4.1

Input voltage

The recommended maximum operating DC Input Voltage is 15V including ripple voltage.

4.2

Reference voltage

No capacitor is required for stability.

4.3

Inhibit function

The inhibit feature allows to put the device in stand-by mode.

With INH pin 1 is higher than 2.2V the device is disabled and the current consumption is

With INH pin lower than 0.8V, the device is enabled.

If the INH pin is left floating, an internal pull up ensures that the voltage at the pin reaches

the inhibit threshold and the device is disabled.

4.4

Multiple units synchronization

Using more than one unit on the same circuit, it is possible to synchronize the switching

frequency, connecting all pin 12 together (see Figure 4).

The unit with higher frequency becomes the master.

4.5

Current limitation

The device has two current limit protections, pulse by pulse and frequency fold back.

The current is sensed through a resistor and if it reaches the threshold, the on time is

reduced and consequently the output voltage, too.

Since the minimum switch ON time (necessary to avoid false overcurrent signal) is not

enough to obtain a sufficiently low duty cycle at 250Hz, the output current could increase

again, in strong overcurrent or short circuit conditions.

For this reason the switching frequency is also reduced to keep the inductor current within

its maximum threshold limit.

The frequency depends on the feedback voltage.

As the feedback voltage decreases (due to the reduced duty cycle), the switching frequency

decrease too.