TLE4678 Datasheet, PDF (23/31 Pages) Infineon Technologies AG – Low Drop Out Linear Voltage Regulator 5 V Fixed Output Voltage

TLE4678
Watchdog Function
Supply
I
RWADJ ,ext
(optional)
WADJ
Control
I_WADJ
RWADJ ,int
VWADJ,th
Int.
Supply
WI Edge
Detect
OR
S1
R
V_DW,hi
I_D,ch
IDW ,dsch
GND
Q
RWO
I_Q
VDD
CQ
Micro-
Controller
WO
IWO
V_DW
&
Reset
WI
I/O
D
CD
BlockDiagram _WatchdogAdjust .vsd
GND
Figure 9 Block Diagram Watchdog Circuit
Figure 10 Watchdog Output “WO”
The watchdog output “WO” is an open collector output with an integrated pull-up resistor. In case a lower-ohmic
“WO” signal is desired, an external pull-up resistor to the output “Q” can be connected. Since the maximum “WO”
sink current is limited, the optional external resistor R_WO,ext needs to be sized to comply with the watchdog output
sink current (see Item 8.2.15 and Item 8.2.16).
Watchdog Input “WI”
The watchdog is triggered by an positive edge at the watchdog input “WI”. The signal is filtered by a bandpass
filter and therefore its amplitude and slope has to comply with the specification Item 8.2.10 to Item 8.2.14. For
details on the test pulse applied, see Figure 11.
V_WI
VWI,hi
tWI,p
VWI,lo
d VWI / d t
t
Figure 11 Test Pulses Watchdog Input WI
Datasheet
23
V_WI
VWI,hi
VWI,lo
1 / fWI
t
Rev. 1.1, 2009-08-27