NCV8141 ON Semiconductor, NCV8141 Datasheet - Page 6

• Manufacturer Part Number: NCV8141
• Description: 5v, 500ma Linear Regulator With Enable, /reset, And Watchdog
• Manufacturer: ON Semiconductor

at which the circuit ceases to regulate against further
reduction in input voltage. Measured when the output
voltage has dropped 100 mV from the nominal value
obtained at 14 V input, dropout voltage is dependent upon
load current and junction temperature.
terminals with respect to ground.
change in the input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
protection circuitry and three logic control functions that
allow a microprocessor to control its own power supply. The
NCV8141 is designed for use in automotive, switch mode
power supply post regulator, and battery powered systems.
noise, low drift, 5.0 V ±3.0% precision output voltage with
low dropout voltage (1.25 V @ I
quiescent current (7.0 mA @ I
short circuit, thermal, and overvoltage protection make it
possible to use this regulator in particularly harsh operating
environments.
(WDI) from the microprocessor or other signal source.
When the signal frequency goes below the externally
programmable limit, a RESET signal is generated (RESET).
Proper operation has been verified at a frequency up to 100
kHz. No abnormal RESET signals will occur with
frequencies lower than 100 kHz and the maximum
Threshold Frequency (96 Hz). An external capacitor
(C
the power on reset (POR) and RESET delay.
conditions: the watchdog signal moves outside of its preset
limits; the output voltage drops out of regulation by more
than 4.5%; or the IC is in its power up sequence. The RESET
signal is independent of V
1.0 V.
function controls the regulator's power consumption. The
NCV8141's output stage and its attendant circuitry are
enabled by setting the ENABLE lead high. The regulator
goes into sleep mode when the ENABLE lead goes low and
the watchdog signal moves outside its preset limit. This
unique combination of control functions in the NCV8141
gives the microprocessor control over its own power down
sequence: i.e. it gives the microprocessor the flexibility to
perform housekeeping functions before it powers down.
Dropout Voltage: The input-output voltage differential
Input Voltage: The DC voltage applied to the input
Line Regulation: The change in output voltage for a
The NCV8141 is a 5.0 V Watchdog Regulator with
Basic regulator performance characteristics include a low
The Watchdog logic function monitors an input signal
The RESET function is activated by any of three
In conjunction with the Watchdog, the ENABLE
DELAY
) programs the watchdog frequency limit as well as
IN
and reliable down to V
OUT
OUT
= 500 mA). On board
= 500 mA) and low
DEFINITION OF TERMS
CIRCUIT DESCRIPTION
http://onsemi.com
OUT
NCV8141
=
6
such that the average chip temperature is not significantly
affected.
change in load current at constant chip temperature.
that does not contribute to the positive load current. The
regulator ground lead current.
ripple voltage to the peak-to-peak output ripple voltage.
output.
Precision Voltage Reference
gap voltage reference in the IC. By adding an error amplifier
into the feedback loop, the output voltage is maintained within
±3.0% over temperature and supply variation.
Output Stage
provides 500 mA (min) of output current while maintaining
a low drop out voltage (1.25 V) and drawing little quiescent
current (7.0 mA).
output stage which in turn improves the IC's efficiency by
preventing excess current from being used and dissipated by
the IC.
Output Stage Protection
circuit and thermal runaway conditions (Figure 8).
output shuts down. This response protects the internal
circuitry and enables the IC to survive unexpected voltage
transients.
Load Regulation: The change in output voltage for a
Quiescent Current: The part of the positive input current
Ripple Rejection: The ratio of the peak-to-peak input
Current Limit: Peak current that can be delivered to the
The regulated output voltage depends on the precision band
The composite PNP-NPN output structure (Figure 7)
The NPN pass device prevents deep saturation of the
The output stage is protected against overvoltage, short
If the input voltage rises above 30 V (e.g. load dump), the
VOLTAGE REFERENCE AND OUTPUT CIRCUITRY
Figure 7. Composite Output Stage of the NCV8141
V
IN
V
OUT