TLD5098EL Datasheet, PDF (25/39 Pages) Infineon Technologies AG – DC/DC Boost, Buck-Boost, SEPIC controller

TLD5098EL
Protection and Diagnostic Functions
example: V_OUT,max=40V
1.25mA
TLD5098
R_OVH
OVFB ⁹
40V _{≅ 33.2kΩ}
1.25mA
GND
12
R_{OVL 1kΩ 1.25V}
Figure 14 Overvoltage Protection description
V_OVFB
V_OVP,max
Overvoltage Protection
ACTIVE
V_OVFB,TH
1.25V
Overvoltage Protection is
disabled
t
Short to GND protection for Highside Return Applications (B2B) from Figure 23
The FBH and FBL pins features a Short to GND detection threshold (V_{FBL,FBH_S2G}). If the potential on those pins is
below this threshold the Device stops his operation. This means that the PWMO signal changes to inactive state
(LOW potential) and the corresponding p-channel (T_DIM2) is switched OFF accordingly and protects the LED chain.
For the B2B application some external components are needed to ensure a LOW potential during a short circuit
event. D1 and D2 are low power diodes (BAS16-03W) and the resistor R_lim (10kOhm) is needed to limit the current
through this path. The diode D3 should be a high power diode and is needed to protect the R_FB and the FBH and
FBL pins in case of an short circuit to GND event. This short circuit detection and protection concept considers
potential faults for LED chains (LED Modules) which are separated from the ECU via two wires (at the beginning
and at the end of the LED chain). If the short circuit condition disappears, the device will re-start with an soft start.
V_bb
C_IN
D1 Rlim
C_BO
D2
V_FBL,FBH
60V
R_FB
wire
harness
LED Module
wire
harness
T_DIM2
D3
D_n
D₁
Short to GND
Short to GND
Normal Operation
T_DIM1
PWMO
FBH
FBL
IN
L_BO
D_BO I_LED
SWO
SWCS
I_{SW TSWVOUT}
4.5V
V_{FBL,FBH_S2G}
Device working with parameter
deviations
Short Circuit detected on
SGND
FBH/FBL
t
Figure 15 Short Circuit to GND Protection
Datasheet
25
Rev. 1.0, 2010-10-13