STLED316S functional description

STLED316S

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3.8

LED drivers

The constant current capability is up to 40 mA per output segment and is set for all the

outputs using a single external resistor. When acting as digit drivers, the outputs source

current to the display anodes. When acting as segment drivers, the LED outputs sink current

from the display cathodes. The outputs are high impedance when not being used as digit or

segment drivers.

Each port configured as a LED digit driver behaves as a digitally-controlled constant current

sink. The LED drivers are suitable for both discrete LEDs and common anode (CA) numeric

LED digits. When fully configured as a LED driver, the STLED316S controls up to 8 LED

segments in a single digit with 8-step logarithmic brightness control for the digits. A single

resistor sets the maximum segment current for all the segments, with a maximum of 40mA

per segment. The STLED316S drives any combination of discrete LEDs and CA digits for

numeric displays.

segment current to a lower maximum value where desired. The user must also ensure that

the maximum current specifications of the LEDs connected to the drivers are not exceeded.

The brightness of the individual digits in the display panel can be controlled separately.

3.9

Interrupt

The device includes an active low level IRQ_N pin to the microprocessor. The STLED316S

generates an interrupt when a key is pressed.

3.10

Operating the device with 3.3 V interface voltages

The device can detect the input voltage levels reference to 3.3 V from the main controller

voltage to STLED316S is greater than 2.9 V, the STLED316S will recognize the signal level

as a valid high and if the input voltage is lower than 1.75 V, it will be recognized as a valid

low level.

For the output signals from the device like DOUT and IRQ_N, the signal level depends on

the external supply to which the external pull up resistor is connected to. Thus this

eliminates the use of any level shifter between the main controller and the STLED316S.