PM6600TR datasheet(33/43 Pages) STMICROELECTRONICS

33 / 43 page

PM6600

Operation description

33/43

7.7

Enable function

The PM6600 is enabled by the EN pin. This pin is active high and, when forced to SGND,

the device is turned off. This pin is connected to a permanently active 2

µA current source;

when sudden device turn-on at power-up is required, this pin must be left floating or

connected to a delay capacitor. When turned off, the PM6600 quickly discharges the Soft-

Start capacitor and turns off the power-MOSFET, the current generators and the LDO. The

power consumption is thus reduced to 20

µA only.

The proper startup sequence is DIM ' VIN ' EN, or VIN ' DIM ' EN. If the dimming signal is

applied after the EN pin, the device will not perform the soft start again, in fact it will start

switching with the maximum current limit in order to recover the output voltage.

In applications where the dimming signal is used to turn on and off the device, the EN pin

can be connected to the DIM pin as shown in Figure 52.

Figure 52.

fDIM enabling schematic

7.8

Thermal protection

In order to avoid damage due to high junction temperature, a thermal shutdown protection is

implemented. When the junction temperature rises above 150 °C (typ.), the device turns off

both the control logic and the boost converter and holds the FAULT pin low.

In order to turn on the device again, it is possible to perform a POR (Power On Reset) once

the junction temperature has been reduced by 30 °C.

DIM

SGND

PM6600

220k

100n

BAS69

PM6600TR bảng dữ liệu(PDF) 33 Page - STMicroelectronics