TS5215CS50 Datasheet, PDF (4/9 Pages) Taiwan Semiconductor Company, Ltd – 300mA Low Noise LDO Voltage Regulator with Enable

TS5215
300mA Low Noise LDO
Voltage Regulator with Enable
Application Information
Enable Input
TS5215 series feature an active-high (>2V) enable (EN) input that allows ON/OFF control of the regulator. Current
drain reduces to “zero” when the device is shutdown, with only micro-amperes of leakage current. The EN is
compatible with CMOS logic interfacing. EN may be directly tied to V_IN and pulled up to the maximum supply voltage.
Input Capacitor Requirement
An input capacitor of 0.1uF or greater is recommended when the device is more than 10” away from the bulk AC
supply capacitance or when the supply is a battery.
Output Capacitor Requirement
The TS5215 series requires an output capacitor to maintain stability and improve transient response is necessary.
2.2uF minimum is recommended. Larger values improve the regulator’s transient response. The output capacitor
value may be increased without limit.
The output capacitor should have an ESR (effective series resistance) less than 5Ω and a resonant frequency above
1MHz. Ultra low ESR capacitors can cause a low amplitude oscillation on the output and/or under damped transient
response. Most of tantalum or aluminum electrolytic capacitors are adequate; film types will work. Since many
aluminum electrolytic have electrolytes that freeze at about –30^oC, solid tantalums are recommended for operation
below –25^oC. At lower values of output current, less output capacitance is required for output stability. The capacitor
can be reduced to 0.47uF for current below 10mA or 0.33uF for currents below 1mA.
Reference Bypass Capacitor
Bypass is connected to the internal voltage reference. A 470pF capacitor (C_BYPASS) connected from Bypass to
Ground quiets this reference, providing a significant reduction in output noise. C_BYPASS reduces the regulator phase
margin; when using C_BYPASS, output capacitors of 2.2uF or greater are generally required to maintain stability.
The star up speed of the TS5215 is inversely proportional to the size of the reference bypass capacitor. Applications
requiring a slow ramp up of output voltage should consider larger values of C_BYPASS. Likewise, if rapid turn on is
necessary, consider omitting C_BYPASS. If output noise is not a major concern, omitted C_BYPASS and leave Bypass open.
No Load Stability
The TS5215 series will remain stable and in regulation with no load, unlike many other voltage regulators. This is
especially important in CMOS RAM keep alive applications.
Adjustable Regulator Design
The adjustable regulator versions can be adjusted to a specific output voltage by using two external resistors to
programming the output voltage anywhere between 1.25 and the 8V maximum operating rating of the family.
Two resistors are used. Resistors can be quite large up to 470kΩ, because of the very high input impedance and low
bias current of the sense comparator, the resistor values are calculated by:
A capacitor from Adjust to Ground provides greatly improved noise performance.
TS5215CX5
V_IN
V_OUT
EN
on
off
C_BYP
470pF
R1
C_OUT
2.2uF
R2
Adjustable Version: V_OUT = 1.24 (1+R2/R1)
(Adjustable output range up to 8V)
4/9
Version: B07