2002-2012 Microchip Technology Inc. DS21350E-page 9
TC1054/TC1055/TC1186
4.0 DETAILED DESCRIPTION
The TC1054, TC1055 and TC1186 are precision fixed
output voltage regulators (If an adjustable version is
desired, please see the TC1070/TC1071/TC1187 data
sheet (DS21353)). Unlike bipolar regulators, the
TC1054, TC1055 and TC1186 supply current does not
increase with load current.
Figure 4-1 shows a typical application circuit, where the
regulator is enabled any time the shutdown input
(SHDN
) is at or above V
IH
, and shutdown (disabled)
when SHDN
is at or below V
IL
. SHDN may be
controlled by a CMOS logic gate or I/O port of a
microcontroller. If the SHDN input is not required, it
should be connected directly to the input supply. While
in Shutdown, supply current decreases to 0.05 µA
(typical), V
OUT
falls to zero volts, and ERROR is open-
circuited.
FIGURE 4-1: Typical Application Circuit.
4.1 ERROR Open-Drain Output
ERROR is driven low whenever V
OUT
falls out of
regulation by more than -5% (typical). This condition
may be caused by low input voltage, output current
limiting or thermal limiting. The ERROR
threshold is 5%
below rated V
OUT
, regardless of the programmed
output voltage value (e.g. ERROR
= V
OL
at 4.75V
(typical) for a 5.0V regulator and 2.85V (typical) for a
3.0V regulator). ERROR output operation is shown in
Figure 4-2.
Note that ERROR
is active when V
OUT
falls to V
TH
and
inactive when V
OUT
rises above V
TH
by V
HYS
.
As shown in Figure 4-1, ERROR
can be used either as
a battery low flag or as a processor RESET
signal (with
the addition of timing capacitor C
2
). R
1
xC
2
should be
chosen to maintain ERROR
below V
IH
of the processor
RESET
input for at least 200 ms to allow time for the
system to stabilize. Pull-up resistor R
1
can be tied to
V
OUT
, V
IN
or any other voltage less than (V
IN
+0.3V).
FIGURE 4-2: Error Output Operation.
4.2 Output Capacitor
A 1 µF (minimum) capacitor from V
OUT
to ground is
recommended. The output capacitor should have an
effective series resistance greater than 0.1 and less
than 10.0, with a resonant frequency above 1 MHz. A
1 µF capacitor should be connected from V
IN
to GND if
there is more than 10 inches of wire between the
regulator and the AC filter capacitor, or if a battery is
used as the power source. Aluminum electrolytic or
tantalum capacitor types can be used (since many
aluminum electrolytic capacitors freeze at approxi-
mately -30°C, solid tantalums are recommended for
applications operating below -25°C). When operating
from sources other than batteries, supply-noise
rejection and transient response can be improved by
increasing the value of the input and output capacitors
and employing passive filtering techniques.
or RESET
V
OUT
SHDN
GND
ERROR
+
V
IN
V
OUT
1µF
+
Battery
+
0.2 µF
C
2
R
1
1MΩ
V+
BATTLOW
1µF
C
1
TC1054
TC1055
TC1186
C
2
Required Only if
ERROR
is used as a
Processor RESET
Signal (see Text)
Shutdown
Control (to
CMOS Logic or
Tie to V
IN
if
unused)
V
TH
V
OUT
ERROR
V
IH
V
OL
HYSTERESIS (V
H
)
t
DELAY
