NCV8502 ON Semiconductor, NCV8502 Datasheet - Page 9

• Manufacturer Part Number: NCV8502
• Manufacturer: ON Semiconductor

control function RESET (Figure 12).
RESET Function
powers up until V
voltage, or when V
than 8.0% below the regulated output voltage. Hysteresis is
included in the function to minimize oscillations.
controlled by a low voltage detection circuit. The circuit is
functionally independent of the rest of the IC thereby
guaranteeing that the RESET signal is valid for V
as 1.0 V.
Adjustable Reset Function
external resistor divider to the R
lead, as displayed in Figure 13. This lead is grounded to
select the default value of 4.6 V.
DELAY Function
external capacitor) delay on the RESET output lead.
to the external DELAY capacitor during the following
proceedings:
DELAY
V
RESET
V
OUT
The NCV8502 contains the microprocessor compatible
A RESET signal (low voltage) is generated as the IC
The RESET output is an open collector NPN transistor,
The reset threshold can be made lower by connecting an
The reset delay circuit provides a programmable (by
The DELAY lead provides source current (typically 2.5 mA)
IN
Figure 12. Reset and Delay Circuit Wave Forms
REGULATOR CONTROL FUNCTIONS
R
ADJ
DELAY
NCV8502
T
Figure 13. Adjustable RESET
d
C
DELAY
OUT
OUT
RESET
V
is within 6.0% of the regulated output
OUT
drops out of regulation,and is lower
T
d
ADJ
R
RST
lead from the V
C
OUT
CIRCUIT DESCRIPTION
OUT
to mP and
System
Power
to mP and
RESET
Port
NCV8502 Series
Threshold
Threshold
http://onsemi.com
as low
DELAY
RESET
OUT
(V
DT
)
9
FLAG/Monitor Function
warning to the microprocessor of a possible reset signal. The
reset signal typically turns the microprocessor off
instantaneously. This can cause unpredictable results with
the microprocessor. The signal received from the FLAG pin
will allow the microprocessor time to complete its present
task before shutting down. This function is performed by a
comparator referenced to the bandgap reference. The actual
trip point can be programmed externally using a resistor
divider to the input monitor (MON) (Figure 14). The typical
threshold is 1.20 V on the MON pin.
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 (1.28 V
typical).
V
BAT
An on−chip comparator is provided to perform an early
Figure 15 shows the device setup for a user configurable
1. During Power Up (once the regulation threshold
2. After a reset event has occurred and the device is
has been verified).
back in regulation. The DELAY capacitor is
discharged when the regulation (RESET threshold)
has been violated. This is a latched incident. The
capacitor will fully discharge and wait for the
device to regulate before going through the delay
time event again.
Figure 15. Adjustable Output Voltage
Figure 14. FLAG/Monitor Function
NCV8502
V
MON
DELAY
R
IN
ADJ
NCV8502
V
V
OUT
ADJ
RESET
GND
FLAG
V
OUT
15 k
1.28 V
5.1 k
ADJ
C
pin is taken from
5.0 V
OUT
C
OUT
V
I/O
RESET
CC
mP