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| TLD2311EL_15 Datasheet, PDF (19/34 Pages) Marl International Limited – Basic LED Driver | |||
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7
ST Pin
The ST pin is a multiple function pin.
TLD2311EL
ST Pin
IST(OL/SC)
No fault
ST
Fault
VST(OL/SC)
Output Control
No fault
Fault
VST
IST(PD)
Figure 13 Block Diagram ST pin
7.1
Diagnosis Selector
If the status pin is unconnected or connected to GND via a high ohmic resistor (VST to be below VST(L)), the ST pin
acts as diagnosis output pin. In normal operation (device is activated) the ST pin is pulled to GND via the internal
pull down current IST(PD). In case of an open load or short circuit to GND condition the ST pin is switched to
VST(OL/SC) after the open load or short circuit detection filter time (Pos. 8.4.9, Pos. 8.4.12).
If the device is operated in PWM operation via the VS and/or EN pins the ST pin should be connected to GND via
a high ohmic resistor (e.g. 470kΩ) to ensure proper device behavior during fast rising VS and/or EN slopes.
If the ST pin is shorted to GND the diagnostic feedback is performed via the IN_SET-pin, which is shown in
Chapter 6.2 and Chapter 8.
7.2
Diagnosis Output
If the status pin is unconnected or connected to GND via a high ohmic resistor (VST to be below VST(L)), it acts as
a diagnostic output. In case of a fault condition the ST pin rises its voltage to VST(OL/SC) (Pos. 8.4.7). Details are
shown in Chapter 8.
7.3
Disable Input
If an external voltage higher than VST(H) (Pos. 8.4.5) is applied to the ST pin, the device is switched off. This
function is used for applications, where multiple drivers should be used for one light function. It is possible to
combine the driversâ fault diagnosis via the ST pins. If a single LED chain fails, the entire light function is switched
off. In this scenario e.g. the diagnostic circuit on the body control module can easily distinguish between the two
cases (normal load or load fault), because nearly no current is flowing into the LED module during the fault
scenario - the drivers consume a current of IS(fault,STu) (Pos. 5.4.5) or IS(dis,ST) (Pos. 5.4.3).
As soon as one LED chain fails, the ST-pin of this device is switched to VST(OL/SC). The other devices used for the
same light function can be connected together via the ST pins. This leads to a switch off of all devices connected
together.
Data Sheet
19
Rev. 1.1, 2015-03-24
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