RT9016 View Datasheet(PDF) - Richtek Technology

Part Name

Description

Manufacturer

RT9016

500mA Peak, Thermal Folded Back CMOS LDO Regulator

Richtek Technology 

RT9016

Preliminary

Applications Information

Like any low-dropout regulator, the external capacitors used

with the RT9016 must be carefully selected for regulator

stability and performance. Using a capacitor whose value

is > 1μF on the RT9016 input and the amount of

capacitance can be increased without limit. The input

capacitor must be located 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 or

tantalum 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 RT9016 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 1μF with ESR

is > 25mΩ on the RT9016 output ensures stability. The

RT9016 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 RT9016 and returned to a clean analog

ground.

Region of Stable COUT ESR vs. Load Current

1001.0000

RT9016-15PB

Unstable Region

CIN = 1μF, X7R

10.0100

1.001

COUT = 1uF

Stable Region

0.10

0.01

0.00

0

Unstable Region (Simulation Verity)

100

200

300

400

500

Load Current (mA)

Figure 1

Bypass Capacitor and Low Noise

Connecting a 22nF between the BP pin and GND pin

significantly reduces noise on the regulator output, it is

critical that the capacitor connection between the BP pin

and GND pin be direct and PCB traces should be as short

as possible. There is a relationship between the bypass

capacitor value and the LDO regulator turn on time. DC

leakage on this pin can affect the LDO regulator output

noise and voltage regulation performance.

Enable Function

The RT9016 features an LDO regulator enable/disable

function. To assure the LDO regulator will switch on, the

EN turn on control level must be greater than 1.2 volts.

The LDO regulator will go into the shutdown mode when

the voltage on the EN pin falls below 0.4 volts. For to

protecting the system, the RT9016 have a quick-discharge

function. If the enable function is not needed in a specific

application, it may be tied to VIN to keep the LDO regulator

in a continuously on state.

Thermal Considerations

Thermal protection limits power dissipation in RT9016.

When the operation junction temperature exceeds 165°C,

the OTP circuit starts the thermal shutdown function turn

the pass element off. The pass element turn on again

after the junction temperature cools by 30°C.

RT9016 lowers its OTP trip level from 165°C to 110°C

when output short circuit occurs (VOUT < 0.4V) as shown

in Figure 2. This limits IC case temperature under 100°C

and provides maximum safety to end users when output

short circuit occurs.

For continue operation, do not exceed absolute maximum

operation junction temperature 125°C. The power

dissipation definition in device is :

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

junction to ambient. The maximum power dissipation can

be calculated by following formula :

www.richtek.com

8

DS9016-03 August 2007

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