TC1305 Datasheet, PDF (5/18 Pages) Microchip Technology – Dual 150mA CMOS LDO With Select Mode™ Operation, Shutdown and Independent RESET Output

3.0 DETAILED DESCRIPTION
The TC1305 is a precision fixed output voltage
regulator that contains two fully independent 150mA
regulator outputs. The device features separate
shutdown modes for low-power operation, and a
common bypass pin that can be used to further reduce
output noise. The Select Mode^™ operation allows the
user to select V_OUT1 and V_OUT2 from three different
values (2.5V, 2.8V, 3.0V), therefore providing high
design flexibility. The CMOS construction of the
TC1305 results to a very low supply current, which
does not increase with load changes. In addition, V_OUT
remains stable and within regulation at no load
currents.
The TC1305 also features an integrated microproces-
sor supervisor that monitors power-up, power-down,
and brown-out conditions. The active low RESET
signal is asserted when the detected voltage V_DET falls
below the reset voltage threshold (2.63V). The RESET
output remains low for 300msec (typical) after V_DET
rises above the reset threshold. The RESET output of
the TC1305 is ensured valid down to V_DET = 1V and is
optimized to reject fast transient glitches on the
monitored power supply line.
TC1305
4.0 TYPICAL APPLICATIONS
4.1 Input and Output Capacitor
The TC1305 is stable with a wide range of capacitor
values and types. A capacitor with a minimum value of
1µF from V_OUT to Ground is required. The output
capacitor should have an effective series resistance
(ESR) of 0.1Ω to 10Ω for a 1µF capacitor and 0.01Ω to
10Ω for a 10µF capacitor. A 1µF capacitor should be
connected from the 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 -20°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.
4.2 Bypass Capacitor
A 0.01µF 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 result in a
longer time period to rated output voltage when power
is initially applied.
4.3 Shutdown Mode
Applying a logic high to each of the shutdown pins turns
on the corresponding output. Each regulator enters
shutdown mode when a logic low is applied in the
corresponding input. During shutdown mode, the out-
put voltage falls to zero, and regulator supply current is
reduced to 0.5µA (max). If shutdown mode is not
necessary, the pins should be connected to V_IN.
© 2002 Microchip Technology Inc.
DS21526A-page 5