TC1223 Datasheet, PDF (4/14 Pages) Microchip Technology – 50mA and 100mA CMOS LDOs with Shutdown

TC1223/TC1224
3.0 DETAILED DESCRIPTION
The TC1223 and TC1224 are precision fixed output
voltage regulators. Unlike bipolar regulators, the
TC1223 and TC1224’s supply current does not
increase with load current. In addition, V_OUT remains
stable and within regulation over the entire 0mA to
I_OUTMAX operating load current range, (an important
consideration in RTC and CMOS RAM battery back-up
applications).
Figure 3-1 shows a typical application circuit. 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 micro-
controller. If the SHDN input is not required, it should be
connected directly to the input supply. While in
shutdown, supply current decreases to 0.05µA (typical)
and V_OUT falls to zero volts.
FIGURE 3-1:
TYPICAL APPLICATION
CIRCUIT
+
1µF
+
Battery
V_IN
V_OUT
TC1223
TC1224
GND
V_OUT
+
1µF
3.1 Output Capacitor
A 1µF (min) capacitor from V_OUT to ground is
recommended. The output capacitor should have an
effective series resistance greater than 0.1Ω and less
than 5.0Ω, and a resonant frequency above 1MHz. A
1µF 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.
SHDN
NC
Shutdown Control
(to CMOS Logic or Tie
to V_IN if unused)
DS21368B-page 4
© 2002 Microchip Technology Inc.