NCV8501 ON Semiconductor, NCV8501 Datasheet - Page 11

• Manufacturer Part Number: NCV8501
• Description: 2.5v, 3.3v, 5.0v, 8v, 10v, Adj./150ma Low Quiescent Current Ldo W/ Reset, Enable And Early Warning
• Manufacturer: ON Semiconductor

Adding Capability
be used with an external pass transistor for additional current
capability. The setup as shown will provide greater than 1
Amp of output current.
of the circuit depicted in Figure 16. As the output voltage
falls (V
the voltage on the FLAG output to go low sending a warning
signal to the microprocessor that a RESET signal may occur
in a short period of time. T
microprocessor has to complete the function it is currently
working on and get ready for the RESET shutdown signal.
V
FLAG Monitor
RESET
FLAG
MON
Ref. Voltage
OUT
V
Figure 18 shows how the adjustable version of parts can
Figure 19 shows the FLAG Monitor waveforms as a result
BAT
Figure 19. FLAG Monitor Circuit Waveform
OUT
C2
0.1 mF
Figure 18. Additional Output Current
), the Monitor threshold is crossed. This causes
V
IN
NCV8501
FLAG MONITOR
V
ADJ
V
OUT
T
WARNING
294 k
100 k
WARNING
R1
R2
MJD31C
is the time the
>1 Amp
C1
47 mF
APPLICATION NOTES
NCV8501 Series
http://onsemi.com
5.0 V
11
*C
Voltage, Delay Switching Threshold, and the Delay Charge
Current. The delay follows the equation:
Example:
three main characteristics of a linear regulator: start-up
delay, load transient response and loop stability.
availability, size and temperature constraints.
should work for most applications, however it is not
necessarily the optimized solution.
V
**C
IN
t DELAY +
0.1 mF
IN
The delay time is controlled by the Reset Delay Low
Using C
Assume reset Delay Low Voltage = 0.
Use the typical value for V
Use the typical value for Delay Charge Current = 2.5 mA.
The output or compensation capacitor helps determine
The capacitor value and type should be based on cost,
The value for the output capacitor C
C
OUT
Figure 20. Test and Application Circuit Showing
IN
required if regulator is located far from the power supply filter
*
required for stability. Capacitor must operate at minimum
t DELAY +
DELAY
STABILITY CONSIDERATIONS
[ C DELAY (V dt * Reset Delay Low Voltage) ]
SETTING THE DELAY TIME
Output Compensation
= 33 nF.
NCV8501
temperature expected
[ 33 nF(1.8 * 0) ]
Delay Charge Current
RESET
2.5 mA
V
OUT
dt
= 1.8 V.
OUT
R
+ 23.8 ms
RST
shown in Figure 20
10 mF
C
OUT
**