RT9013B 데이터 시트보기 (PDF) - Richtek Technology

부품명

상세내역

일치하는 목록

RT9013B

300mA, Low Dropout, Low Noise Ultra-Fast Without Bypass Capacitor CMOS LDO Regulator

Richtek Technology 

RT9013B

Applications Information

Like any low-dropout regulator, the external capacitors used

with the RT9013B must be carefully selected for regulator

stability and performance. Using a capacitor whose value

is > 1uF / X7R on the RT9013B input and the amount of

capacitance can be increased without limit. The input

capacitor must be located at a distance of not more than

0.5 inch from the input pin of the IC and returned to a clean

analog ground. Any good quality ceramic can be used for

this capacitor. The capacitor with larger value and lower

ESR (equivalent series resistance) provides better PSRR

and line-transient response.

The output capacitor must meet both requirements for

minimum amount of capacitance and ESR in all LDOs

application. The RT9013B is designed specifically to work

with low ESR ceramic output capacitor in space-saving

and performance consideration. Using a ceramic capacitor

whose value is at least 1uF with ESR is > 20mΩ on the

RT9013B output ensures stability. The RT9013B still works

well with output capacitor of other types due to the wide

stable ESR range. Figure 1. shows the curves of allowable

ESR range as a function of load current for various output

capacitor values. Output capacitor of larger capacitance

can reduce noise and improve load transient response,

stability, and PSRR. The output capacitor should be located

not more than 0.5 inch from the VOUT pin of the RT9013B

and returned to a clean analog ground.

Region of Stable COUT ESR vs. Load Current

100

Unstable Range

10

1

Stable Range

0.1

0.01

VIN = 5V

CIN = COUT = 1uF/X7R

0.001

Unstable Range

0

50

100 150 200 250 300

Load Current (mA)

Figure 1

Enable

The RT9013B goes into sleep mode when the EN pin is in

a logic low condition. During this condition, the RT9013B

has an EN pin to turn on or turn off the regulator, When the

EN pin is logic hight the regulator will be turned on. The

supply current to 0.7uA typical. The EN pin may be directly

tied to VIN to keep the part on. The Enable input is CMOS

logic and cannot be left floating.

PSRR

The power supply rejection ratio (PSRR) is defined as the

gain from the input to output divided by the gain from the

supply to the output. The PSRR is found to be

PSRR

=

20

×

log⎜⎛

⎝

ΔGain Error

ΔSupply

⎟⎞

⎠

Note that in heavy load measuring, Δsupply will cause

Δtemperature. And Δtemperature will cause Δoutput

voltage. So the temperature effect is include in heavy load

PSRR measuring.

Current Limit

The RT9013B contains an independent current limiter, which

monitors and controls the pass transistor's gate voltage,

limiting the output current to 0.4A (typ.). The output can

be shorted to ground indefinitely without damaging the part.

Thermal Considerations

Thermal protection limits power dissipation in the RT9013B.

When the operation junction temperature exceeds 170°C,

the OTP circuit starts the thermal shutdown function and

turns the pass element off. The pass element will be turned

on again after the junction temperature cools by 30°C.

For continuous operation, do not exceed absolute

maximum operation junction temperature 125°C. The

power dissipation definition in the device is calculated as

follows :

PD = (VIN − VOUT) x IOUT + VIN x IQ

The maximum power dissipation depends on the thermal

resistance of IC package, PCB layout, the rate of

surroundings airflow and temperature difference between

DS9013B-02 April 2011

www.richtek.com

7

Share Link: