Pin functions

UM0422

6/14

3

Pin functions

4

Description of the board

The evaluation board module (EVM) is configured as constant current supply. An external

connector.

For proper operation, the minimum input voltage must always be:

Equation 2

where

Table 2.

Pin function

Pin.

No.

Symbol

Function

1

VCC

Supply voltage. Must be closely decoupled to ground.

2PWM

PWM dimming input. With PWM high the internal power MOSFET is turned on

and the LEDs current goes to the set value. With PWM low the power MOSFET

is turned off and the LEDs current goes to zero. While the PWM input is

switching, the overall circuitry remains on. This is necessary and needed in

order to implement two important features: short delay time and controlled slope

for the current.

3EN

Shutdown pin. With EN high the STCS1 is in ON mode. When the EN pin is low

the device is completely off and the current consumption is less than 1 µA.

4

DRAIN

Internal power N-MOSFET drain.

5FB

Internal power N-MOSFET source. This pin is the voltage pin feedback. The

control loop regulates the voltage in this pin to 100 mV. The LEDs current is set

with an external sensing resistor connected between this pin and GND.

6

GND

Ground pin.

7SLOPE

STCS1A capacitor for slope control. This pin permits setting the slope of the rise

and fall edge of LEDs current. The rise and fall slope of the current is controlled

If this pin is not connected the slope control feature is disable and the STCS1A

part has the same behavior of STCS1.

8DISC

low regardless of the PWM pin status. This information can be used by the

system to alert that a problem occurs in the LEDs.

Exposed

pad

Connect to the ground plane for effective power dissipation. The exposed pad is

internally connected to ground.

V

INMIN

nV

FMAX

•

V

DROPoutMAX

+

=

-

-

-

nV

FMAX

•

-