TJ49150 参数 Datasheet PDF下载

TJ49150

APPLICATION INFORMATION

The TJ49150 is a high performance, low dropout linear regulator, designed for high current application that

requires fast transient response. The TJ49150 operates from two input supply voltages, significantly reducing

dropout voltage. The TJ49150 is designed so that a minimum of external component are necessary.

Bias Supply Voltage

The TJ49150 control circuitry is supplied by the BIAS pin which requires a very low bias current even at the

maximum output current level. A bypass capacitor on the bias pin is recommended to improve the

performance of the TJ49150 during line and load transient. A small ceramic capacitor from BIAS pin to ground

reduces high frequency noise that could be injected into the control circuitry from the bias rail. In practical

applications, a 1μF capacitor and smaller valued capacitors such as 0.01μF or 0.001μF in parallel with that larger

capacitor may be used to decouple the bias supply. The BIAS input voltage must be 2.1V above the output

voltage, with a minimum BIAS input voltage of 3.0V.

Adjustable Regulator Design

The TJ49150 adjustable version allows fixing output voltage anywhere between 0.8V and 2.0V using two external

resistors as presented in the typical application circuit. The resistor values are given by;



V



R1

=

R2

× 

OUT

−

1





0.8







It is suggested to use R1 values lower than 10kΩ to obtain better load transient performances. Even, higher

values up to 100kΩ are suitable.

Enable

The SOP-8 and SOP8-PP types of TJ49150 feature an active high Enable input(EN) that allows on/off control of the

regulator. The enable function of TJ49150 has hysteresis characteristics. The enable input allows on control of

the regulator with the enable pin voltage of 2.0V or above. When the enable input voltage lowers under 0.4V,

the enable input allows off control of the regulator. If not in used for logic control, EN pin must be tied to BIAS

voltage for proper operation. When a pull-up resistor is connected between EN pin and V

EN

signal(or V

BIAS

line),

the resistance should be kept under 10kΩ. The EN pin must not be left at high impedance.

Supply Power Sequencing

In common applications where the power on transient of IN and BIAS voltages are not particularly fast(Tr>100μs),

no power sequencing is required. Where voltage transient input is very fast(Tr<100μs), it is recommended to

have the IN voltage present before or, at least, at the same time as the BIAS voltage in order to avoid over voltage

spikes during the power on transient.

Output Capacitors

The TJ49150 requires a minimum output capacitance to maintain stability. The TJ49150 is specifically designed to

be stable with a ceramic chip, tantalum, and aluminum electrolytic capacitor. A 10μF of ceramic chip capacitor or

a 33μF tantalum or aluminum electrolytic capacitor would satisfy most applications. Its minimum value of

ceramic chip capacitor is 1μF and of tantalum or aluminum electrolytic capacitor is 22μF. They might be

increased if output current is high.

Input Capacitor

An input capacitor of minimum 1μF of chip ceramic capacitor or 10μF of tantalum or aluminum electrolytic

8

July 2011

HTC