TC1014 Datasheet, PDF (6/20 Pages) TelCom Semiconductor, Inc – 50mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS

TC1014/TC1015/TC1185
3.0 DETAILED DESCRIPTION
The TC1014/TC1015/TC1185 are precision fixed
output voltage regulators. (If an adjustable version is
desired, please see the TC1070/TC1071/TC1187 data
sheet.) Unlike bipolar regulators, the TC1014/TC1015/
TC1185 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 ranges (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
microcontroller. If the SHDN input is not required, it
should be connected directly to the input supply. While
in shutdown, supply current decreases to 0.05µA
(typical), V_OUT falls to zero volts.
FIGURE 3-1:
TYPICAL APPLICATION
CIRCUIT
+
V_IN
V_OUT
+
1µF
TC1014
TC1015
Battery
TC1185
GND
V_OUT
+
1µF
3.1 Bypass Input
A 470pF capacitor connected from the Bypass input to
ground reduces noise present on the internal
reference, which in turn significantly reduces output
noise. If output noise is not a concern, this input may be
left unconnected. Larger capacitor values may be
used, but results in a longer time period to rated output
voltage when power is initially applied.
3.2 Output Capacitor
A 1µF (min) capacitor from V_OUT to ground is required.
The output capacitor should have an effective series
resistance greater than 0.1Ω and less than 5Ω. 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 approximately -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 Bypass
Shutdown Control
(to CMOS Logic or Tie
to V_IN if unused)
470pF
Reference
Bypass Cap
(Optional)
DS21335B-page 6
© 2002 Microchip Technology Inc.