L4995J STMicroelectronics, L4995J Datasheet - Page 18

• Manufacturer Part Number: L4995J
• Description: IC REG LDO 5V 500MA POWERSSO-12
• Manufacturer: STMicroelectronics

Specifications of L4995J

• Regulator Topology: Positive Fixed
• Voltage - Output: 5V
• Voltage - Input: 5.6 ~ 31 V
• Voltage - Dropout (typical): 0.27V @ 400mA
• Number Of Regulators: 1
• Current - Output: 500mA
• Current - Limit (min): 600mA
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: PowerSSO-12
• Number Of Outputs: 1
• Polarity: Positive
• Output Voltage: 5 V
• Output Type: Fixed
• Dropout Voltage (max): 0.5 V at 400 mA
• Output Current: 500 mA
• Line Regulation: 25 mV
• Load Regulation: 25 mV
• Voltage Regulation Accuracy: 2 %
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application information
3.3
18/34
Watchdog
A connected microcontroller is monitored by the watchdog input W
the Reset output pin is set to low. The pulse sequence time can be set within a wide range
with the external capacitor, C
constant current Icwd. If the lower threshold V
To prevent this the microcontroller must generate a positive edge during the discharge of the
capacitor before the voltage has reached the threshold V
minimum time t, during which the micro-controller must output the positive edge, the
following equation can be used:
Equation 3
Every W
happens when the lower threshold is reached. When the voltage reaches the upper
threshold, V
voltage at the watchdog timer capacitor C
Figure 29. Watchdog timing diagram
W
W
V
V
R
R
cw
cw
es
es
i
i
i
positive edge switches the current source from discharging to charging. The same
whth
, the current switches from charging to discharging. The result is a saw-tooth
(V
tw
Doc ID 13103 Rev 10
. The watchdog circuit discharges the capacitor C
whth
-V
wlth
T
T
) x C
tw
wol
wol
.
wlth
tw
= I
is reached, a watchdog reset is generated.
cwd
x t
T
T
wop
wop
wlth
. In order to calculate the
i
. If pulses are missing,
tw
, with the
V
V
V
V
L4995
whth
whth
wlth
wlth