PRELIMINARY INFORMATION
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
TC1014
PIN DESCRIPTION
Pin No.
(SOT-23A-5)
Symbol
Description
1
2
3
VIN
Unregulated supply input.
Ground terminal.
GND
SHDN
Shutdown control input. The regulator is fully enabled when a logic high is applied to this
input. The regulator enters shutdown when a logic low is applied to this input. During
shutdown, output voltage falls to zero, and supply current is reduced to under 1 microamp
(typical).
4
5
Bypass
VOUT
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
Regulated voltage 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.
DETAILED DESCRIPTION
The TC1014 is a precision fixed output voltage regula-
tor. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regula-
tors, the TC1014 supply current does not increase with load
current. In addition, VOUT remains stable and within regula-
tion at very low load currents (an important consideration in
RTC and CMOS RAM battery back-up applications).
Figure 1 shows a typical application circuit. The regula-
tor is enabled any time the shutdown input (SHDN) is at or
above VIH, and shutdown (disabled) when SHDN is at or
below VIL. 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) and VOUT falls to zero volts.
Output Capacitor
A 1µF (min) capacitor from VOUT to ground is recom-
mended. The output capacitor should have an effective
series resistance of 5Ω or less, and a resonant frequency
above1MHz.A1µFcapacitorshouldbeconnected fromVIN
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
thepowersource. Aluminumelectrolyticortantalumcapaci-
tor types can be used. (Since many aluminum electrolytic
capacitors freeze at approximately – 30°C, solid tantalums
arerecommendedforapplicationsoperatingbelow –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.
V
V
V
OUT
OUT
IN
1µF
1µF
Thermal Considerations
BATTERY
GND
Thermal Shutdown
TC1014
Integrated thermal protection circuitry shuts the regula-
tor off when die temperature exceeds 160°C. The regulator
remains off until the die temperature drops to approximately
150°C.
SHDN
Bypass
470pF
Reference
Bypass Cap
(Optional)
Power Dissipation
The amount of power the regulator dissipates is prima-
rilyafunctionofinputandoutputvoltage,andoutputcurrent.
The following equation is used to calculate worst case
actual power dissipation:
Shutdown Control
(to CMOS Logic or Tie to V if Unused)
IN
Figure 1. Typical Application Circuit
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
TC1014-01-6/5/97
3
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