TLD2311EL Datasheet, PDF (11/34 Pages) Infineon Technologies AG – 3 Channel High Side Current Source Basic LED Driver

TLD2311EL
EN Pin
5.2
Internal Supply Pin
The EN pin can be used to supply the internal logic. There are two typical application conditions, where this feature
can be used:
1) In “DC/DC control Buck” configurations, where the voltage V_s can be below 5.5V.
2) In configurations, where a PWM signal is applied at the Vbatt pin of a light module. The buffer capacitor C_BUF is
used to supply the Basic LED Driver IC during Vbatt low (V_s low) periods. This feature can be used to minimize
the turn-on time to the values specified in Pos. 9.2.13. Otherwise, the power-on reset delay time t_POR (Pos. 5.4.8)
has to be considered.
The capacitor can be calculated using the following formula:
C_BUF
=
t_LOW(max)
⋅
-----------------^I--^E---^N----⁽--^L---^S---⁾----------------
V_S – V_D1 – V_S(POR)
(1)
See also a typical application drawing in Chapter 10.
V_BATT
D1
CBUF
VS
Internal
supply
EN
Thermal
protection
Output
control
IN_SET3
IN_SET2 Current
IN_SET1 ^adjust
Basic LED Driver
OUT3
OUT2
OUT1
GND
R_SET3 R_SET2 R_SET1
GND
Figure 5 External circuit when applying a fast PWM signal on V_BATT
Data Sheet
11
Rev. 1.0, 2013-08-08