Application Information
Application Information
The value of the output capacitor can be increased
without limit. Higher capacitance values help to
improve transient response and ripple rejection and
reduce output noise.
The TS39100/1/2/3 series are high performance with
low dropout voltage regulator suitable for moderate to
high current and voltage regulator application. Its
630mV dropout voltage at full load and over
temperature makes it especially valuable in battery
power systems and as high efficiency noise filters in
post regulator applications. Unlike normal NPN
transistor design, where the base to emitter voltage
drop and collector to emitter saturation voltage limit the
minimum dropout voltage, dropout performance of the
PNP output of these devices is limited only by low Vce
saturation voltage.
Input Capacitor Requirement
An input capacitor of 1uF or greater is recommended
when the device is more than 4” away from the bulk
AC supply capacitance or when the supply is a battery.
Small, surface mount, ceramic chip cpapcitors can be
used for bypassing. Larger values will help to improve
ripple rejection by bypassing the input to the regulator,
further improving the integrity of the output voltage.
The TS39100/1/2/3 series is fully protected from
damage due to fault conditions. Linear current limiting is
provided. Output current during overload conditions is
constant. Thermal shutdown the device when the die
temperature exceeds the maximum safe operating
temperature. Transient protection allows device survival
even when the input voltage spikes above and below
nominal. The output structure of these regulators allows
voltages in excess of the desired output voltage to be
applied without reverse current flow.
Minimum Load Current
The TS39100/1/2/3 series is specified between finite
loads. If the output current is too small leakage
currents dominate and the output voltage rises. A
10mA minimum load current is necessary for proper
regulation.
Adjustable Regulator Design
The adjustable regulator versions (TS39102) is allow
to programming the output voltage anywhere between
1.25 and the 16V maximum operating rating of the
family.
Output Capacitor Requirement
The TS39100/1/2/3 series requires an output capacitor
to maintain stability and improve transient response is
necessary. The value of this capacitor is dependent
upon the output current, lower currents allow smaller
capacitors. TS39100/1/2/3 series output capacitor
selection is dependent upon the ESR of the output
capacitor to maintain stability. When the output
capacitor is 10uF or greater, the output capacitor should
have an ESR less than 2Ω. This will improve transient
response as well as promote stability. Ultra low ESR
capacitors (<100mΩ), such as ceramic chip capacitors,
may promote instability. These very low ESR levels may
cause an oscillation and/or under damped transient
response. A low ESR solid tantalum capacitor works
extremely well and provides good transient response
and stability over temperature aluminum electrolytes
can also be used, as long as the ESR of the capacitor is
<2Ω.
Two resistors are used. Resistors can be quite large
up to 1Mꢀ, because of the very high input impedance
and low bias current of the sense comparator, the
resistor values are calculated by:
R1 = R2 * [(Vout / 1.24) – 1]
Where Vout is the desired output voltage. Above
application circuit shows component definition.
Applications with widely varying load currents may
scale the resistors to draw the minimum load current
required for proper operation.
TS39100/1/2/3
6-10
2004/06 rev. E
TSC [ TAIWAN SEMICONDUCTOR COMPANY, LTD ]
