Application information
Figure 32. Application schematic
+5V
R prot CS_DIS
MCU R prot
IN
R prot
C ext
R
SENSE
CS
45V
GND
V
CC
20V
OUT
VN5E010AH
D ld
3.2
24/37
D ld
is necessary (voltage transient suppressor) if the load dump peak voltage exceeds the
V
CC
max DC rating. The same applies if the device is subject to transients on the V
CC that are greater than the ones shown in the ISO 7637-2 2004 (E) table.
line
MCU I/Os protection
When negative transients are present on the V
CC
line, the control pins is pulled negative to approximatly -1.5 V. ST suggests to insert a resistor (R prot microcontroller I/Os pins to latch-up.
) in line to prevent the
The value of these resistors is a compromise between the leakage current of microcontroller and the current required by the HSD I/Os (input levels compatibility) with the latch-up limit of microcontroller I/Os.
Equation 1
-V
CCpeak
/ I latchup
R prot
(V
OH C
- V
IH
) / I
IHmax
Calculation example:
For V
CCpeak
= - 1.5 V; I latchup
20 mA; V
OH C
4.5 V
75 R prot
240 k .
Recommended values: R prot
=10 k C
EXT
=10 nF .
Doc ID 15984 Rev 3
