MCP1525/41
DS21653C-page 4 2001-2012 Microchip Technology Inc.
1.1.4 DROPOUT VOLTAGE
The dropout voltage of these devices is measured by
reducing V
IN
to the point where the output drops by 1%.
Under these conditions the dropout voltage is equal to:
EQUATION 1-2:
The dropout voltage is affected by ambient
temperature and load current.
In Figure 2-18, the dropout voltage is shown over a
negative and positive range of output current. For
currents above zero milliamps, the dropout voltage is
positive. In this case, the voltage reference is primarily
powered by V
IN
. With output currents below zero
milliamps, the dropout voltage is negative. As the
output current becomes more negative, the input
current (I
IN
) reduces. Under this condition, the output
current begins to provide the needed power to the
voltage reference.
1.1.5 LINE REGULATION
Line regulation is a measure of the change in output
voltage (V
OUT
) as a function of a change in the input
voltage (V
IN
). This is expressed as V
OUT
/V
IN
and is
measured in either µV/V or ppm. For example, a 1 µV
change in V
OUT
caused by a 500 mV change in V
IN
would net a V
OUT
/V
IN
of 2 µV/V, or 2 ppm.
1.1.6 LOAD REGULATION (V
OUT
/I
OUT
)
Load regulation is a measure of the change in the
output voltage (V
OUT
) as a function of the change in
output current (I
OUT
). Load regulation is usually
measured in mV/mA.
1.1.7 INPUT CURRENT
The input current (operating current) is the current that
sinks from V
IN
to V
SS
without a load current on the out-
put pin. This current is affected by temperature and the
output current.
1.1.8 INPUT VOLTAGE REJECTION
RATIO
The Input Voltage Rejection Ratio (IVRR) is a measure
of the change in output voltage versus the change in
input voltage over frequency, as shown in Figure 2-7.
The calculation used for this plot is:
EQUATION 1-3:
1.1.9 LONG-TERM OUTPUT STABILITY
The long-term output stability is measured by exposing
the devices to an ambient temperature of 125°C
(Figure 2-9) while configured in the circuit shown in
Figure 1-1. In this test, all electrical specifications of the
devices are measured periodically at +25°C.
FIGURE 1-1: Dynamic Life Test
Configuration.
1.1.10 OUTPUT VOLTAGE HYSTERESIS
The output voltage hysteresis is a measure of the
output voltage error once the powered devices are
cycled over the entire operating temperature range.
The amount of hysteresis can be quantified by
measuring the change in the +25°C output voltage after
temperature excursions from +25°C to +85°C to +25°C
and also from +25°C to -40°C to +25°C.
IVRR 20
V
IN
V
OUT
--------- ----
log dB=
V
SS
V
OUT
V
IN
C
L
V
IN
=5.5V
R
L
±2 mA
square wave
@10Hz
MCP1525
MCP1541
1µF
21653C.book Page 4 Thursday, January 10, 2013 12:55 PM
