TC2014 Datasheet, PDF (10/18 Pages) Microchip Technology – 50 mA, 100 mA, 150 mA CMOS LDOs with Shutdown and Reference Bypass

TC2014/2015/2185
4.0 DETAILED DESCRIPTION
The TC2014, TC2015 and TC2185 are precision fixed
output voltage regulators (If an adjustable version is
needed, see the TC1070, TC1071 or TC1187
(DS21353) datasheet.) Unlike bipolar regulators, the
TC2014, TC2015 and TC2185 supply current does not
increase with load current. In addition, the LDO output
voltage is stable using 1 µF of ceramic or tantalum
capacitance over the entire specified input voltage
range and output current range.
Figure 4-1 shows a typical application circuit. The reg-
ulator is enabled any time the shutdown input (SHDN)
is at or above V_IH, and disabled (shutdown) 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) and V_OUT falls to
zero volts.
1
V_IN
++
1 µF
V_OUT ⁵
V_OUT
+
1 µF
Battery
2
TC2014
GND _TC2015
TC2185
3
SHDN
4
Bypass
Shutdown Control
(from Power Control Logic)
0.01 µF
Reference
Bypass Cap
(Optional)
FIGURE 4-1:
Typical Application Circuit.
4.1 Bypass Input
A 0.01 µF ceramic 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 the result is a longer time period to rated
output voltage when power is initially applied.
4.2 Output Capacitor
A 1 µF (min) capacitor from V_OUT to ground is required.
The output capacitor should have an esr (effective
series resistance) of 0.01Ω to 5Ω for V_OUT ≥ 2.5V, and
0.05Ω. to 5Ω for V_OUT < 2.5V. Ceramic, tantalum or alu-
minum electrolytic capacitors can be used. When using
ceramic capacitors, X5R and X7R dielectric material
are recommended due to their stable tolerance over
temperature. However, other dielectrics can be used as
long as the minimum output capacitance is maintained.
4.3 Input Capacitor
A 1 µF capacitor should be connected from V_IN to GND
if there is more than 10 inches of wire between the reg-
ulator and this AC filter capacitor, or if a battery is used
as the power source. Aluminum, electrolytic or tanta-
lum capacitors can be used (Since many aluminum
electrolytic capacitors freeze at approximately -30°C,
solid tantalum are recommended for applications oper-
ating 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.
DS21662C-page 10
 2003 Microchip Technology Inc.