TS5218

800mA Ultra Low Dropout

Voltage Regulator with Enable

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Version: A09

Application Information (Continue)

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 capacitors 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.

Minimum Load Current

The TS5218 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.

Enable Input

TS5218 versions feature an active-high 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 input has

TTL/CMOS compatible thresholds for simple interfacing with logic interfacing. EN may be directly tied to VIN and

pulled up to the maximum supply voltage.

Adjustable Regulator Design

The TS5218 is allowed to programming the output voltage anywhere between 1.25 and the 16V maximum operating

rating of the family. Two resistors are used. Resistors can be quite large up to 1MΩ, because of the very high input

impedance and low bias current of the sense comparator, the resistor values are calculated by:

widely varying load currents may scale the resistors to draw the minimum load current required for proper operation.

Transient Response and 3.3V to 2.5V or 2.5V to 1.8V Conversion

TS5218 has excellent transient response to variations in input voltage and load current. The device have been

designed to respond quickly to load current variations and input voltage variations. Large output capacitors are not

required to obtain this performance. A standard 10uF output capacitor, preferably tantalum, is all that is required.

Larger values help to improve performance even further. By virtue of its low dropout voltage, this device does not

saturate into dropout as readily as similar NPN base designs. When converting from 3.3V to 2.5V or 2.5V to 1.8V, the

NPN based regulators are already operating in dropout, with typical dropout requirements of 1.2V or greater,. To

convert down to 2.5V or 1.8V without operating in dropout, NPN based regulators require an input voltage of 3.7V at

the very least. The TS5218 regulator will provide excellent performance with an input as low as 3.0V or 2.5V

respectively. This gives the PNP based regulators a distinct advantage over older, NPN based linear regulators.