L4979D-E STMicroelectronics, L4979D-E Datasheet - Page 11
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L4979D-E
Manufacturer Part Number
L4979D-E
Description
IC REG PROGR WATCHDOG 8SOIC
Manufacturer
STMicroelectronics
Type
Step-Down (Buck)r
Datasheet
1.L4979DTR-E.pdf
(22 pages)
Specifications of L4979D-E
Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
5V
Current - Output
150mA
Voltage - Input
5.6 ~ 31 V
Operating Temperature
-40°C ~ 150°C
Mounting Type
Surface Mount
Package / Case
8-SOIC (0.236", 6.0mm Width)
Power - Output
*
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Frequency - Switching
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Available stocks
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3.3
Table 10.
Watchdog
The watchdog input W
reset output R
thorough the external capacitor C
the constant current I
generated. To prevent this reset, the microcontroller must generate a positive edge during
the discharge of the capacitor before the voltage has reached the threshold V
calculate the minimum time T
edge, the following equation can be used:
Each W
happens when the lower V
threshold V
voltage at the watchdog timer capacitor C
Figure 4.
i
positive edge switches the current source from discharging to charging; the same
whth
Reset time diagram
Watchdog time diagram
es
the current switches from charging to discharging. The result is a saw tooth
is set to low. The pulse sequence time can be set within a wide range
cwd
i
monitors a connected microcontroller. If pulses are missing, the
. If the lower threshold V
wlth
(
V
dis
whth
Doc ID 10262 Rev 7
threshold is reached. When the voltage reaches the upper
during which the microcontroller must generate the positive
tw
. The watchdog circuit discharges the capacitor C
–
V
wlth
tw
)
.
×
C
tw
wlth
=
is reached, a watchdog reset is
I
cwd
×
T
dis
wlth
. In order to
tw
11/22
with