NCV8503 ON Semiconductor, NCV8503 Datasheet - Page 10

• Manufacturer Part Number: NCV8503
• Description: 2.5v, 3.3v, 5.0v, Adjustable/400ma Ldo W/ Reset, Delay, Adjustable Reset, Enable And Early Warning
• Manufacturer: ON Semiconductor

V
Voltage Adjust
output voltage. The feedback to the V
a voltage divider referenced to the output voltage. The loop
is balanced around the Unity Gain threshold (1.30 V
typical). JEDEC standard JESD78 requires -100 mA trigger
test conditions. V
of the circuit depicted in Figure 18. As the input voltage falls
(V
voltage on the FLAG output to go low.
Voltage, Delay Switching Threshold, and the Delay Charge
Current. The delay follows the equation:
Example:
FLAG
MON
Flag Monitor
Ref. Voltage
MON
t DELAY +
Figure 19 shows the device setup for a user configurable
Figure 20 shows the FLAG Monitor waveforms as a result
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 = 4.2 mA.
MON
Figure 20. FLAG Monitor Circuit Waveform
), the Monitor threshold is crossed. This causes the
5.0 V options).
t DELAY +
DELAY
[ C DELAY (V dt * Reset Delay Low Voltage) ]
SETTING THE DELAY TIME
ADJ
= 33 nF.
FLAG MONITOR
[ 33 nF(1.8 * 0) ]
conforms to -75 mA test conditions.
Delay Charge Current
4.2 mA
dt
= 1.8 V (2.5 V, 3.3 V, and
ADJ
+ 14 ms
pin is taken from
APPLICATION NOTES
NCV8503 Series
http://onsemi.com
10
*C
three main characteristics of a linear regulator: start-up
delay, load transient response and loop stability.
availability, size and temperature constraints. A tantalum or
aluminum electrolytic capacitor is best, since a film or
ceramic capacitor with almost zero ESR can cause
instability. The aluminum electrolytic capacitor is the least
expensive solution, but, if the circuit operates at low
temperatures (-25°C to -40°C), both the value and ESR of
the capacitor will vary considerably. The capacitor
manufacturers data sheet usually provides this information.
should work for most applications, however it is not
necessarily the optimized solution.
V
**C
IN
0.1 mF
IN
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 21. 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
STABILITY CONSIDERATIONS
NCV8503
Figure 19. Adjustable Output
Output Compensation
NCV8503
V
temperature expected
V
OUT
ADJ
RESET
Voltage
V
OUT
1.28 V
15 k
5.1 k
OUT
R
RST
shown in Figure 21
≈5.0 V
C
OUT
33 mF
C
OUT
**