RT9149 datasheet(8/13 Pages) RICHTEK

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RT9148/9

DS9148/9-04

October 2013

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Applications Information

The RT9148/9 is a high performance operational amplifier

capable of driving large loads for different applications. A

high slew rates, rail-to-rail input and output capability, and

low power consumption are the features which make the

RT9148/9 ideal for LCD applications. The RT9148/9 also

has wide bandwidth and phase margin to drive a load with

10k

Ω resistance and 10pF capacitance.

Operating Voltage

The RT9148/9 total supply voltage range is guaranteed

from 6V to 20V. The specifications are stable over both

the full supply range and operating temperatures from

−40°C to 85°C. The output swing of the RT9148/9 typically

extends to within 1.5V of positive/negative supply rails

with 50mA load current source/sink. Decreasing the load

current will obtain an output swing even closer to the

supply rails.

Short Circuit Condition

An internal short circuit protection is implemented to

protect the device from output short circuit. The

RT9148/9 limits the short circuit current to

±350mA if the

output is directly shorted to positive/negative supply rails.

LCD Panel Applications

The RT9148/9 is mainly designed for LCD V-com buffer.

The operational amplifier has 350mA instantaneous source/

sink peak current.

Thermal Considerations

For continuous operation, do not exceed absolute

maximum junction temperature. The maximum power

dissipation depends on the thermal resistance of the IC

package, PCB layout, rate of surrounding airflow, and

difference between junction and ambient temperature. The

maximum power dissipation can be calculated by the

following formula :

PD(MAX) = (TJ(MAX)

− TA) / θJA

where TJ(MAX) is the maximum junction temperature, TA is

the ambient temperature, and

θJA is the junction to ambient

thermal resistance.

For recommended operating condition specifications, the

maximum junction temperature is 125

°C. The junction to

ambient thermal resistance,

θJA, is layout dependent. For

WDFN-6L 2x2 packages, the thermal resistance,

θJA, is

47.5

°C/W on a standard JEDEC 51-7 four-layer thermal

test board. For TSOT-23-5 packages, the thermal

resistance,

θJA, is 230.6°C/W on a standard JEDEC 51-7

four-layer thermal test board. For UDFN-6L 2x2 packages,

the thermal resistance,

θJA, is 47.7°C/W on a standard

JEDEC 51-7 four-layer thermal test board. For WDFN-8L

3x3 packages, the thermal resistance,

θJA, is 31°C/W on

a standard JEDEC 51-7 four-layer thermal test board. The

maximum power dissipation at TA = 25

°C can be calculated

by the following formula :

PD(MAX) = (125

°C − 25°C) / (47.5°C/W) = 2.1W for

WDFN-6L 2x2 package

PD(MAX) = (125

°C − 25°C) / (230.6°C/W) = 0.43W for

TSOT-23-5 package

PD(MAX) = (125

°C − 25°C) / (47.7°C/W) = 2.09W for

WDFN-6L 2x2 package

PD(MAX) = (125

°C − 25°C) / (31°C/W) = 3.22W for

WDFN-8L 3x3 package

The maximum power dissipation depends on the operating

ambient temperature for fixed TJ(MAX) and thermal

resistance,

θJA. The derating curve in Figure 1 allows the

designer to see the effect of rising ambient temperature

on the maximum power dissipation.

Figure 1. Derating Curve of Maximum Power Dissipation

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

3.6

4.0

100

125

Ambient Temperature (°C)

Four-Layer PCB

WDFN 6L 2x2

WDFN 8L 3x3

TSOT-23-5

UDFN 6L 2x2

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