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LT1964ES5-SD

200mA, Low Noise, Low Dropout Negative Micropower Regulator in ThinSOT

Linear Technology 

LT1964

APPLICATIO S I FOR ATIO

20

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

0

X5R

–20

–40

–60

Y5V

–80

–100

0 2 4 6 8 10 12 14 16

DC BIAS VOLTAGE (V)

1964 F02

Figure 2. Ceramic Capacitor DC Bias Characteristics

40

20

0

X5R

–20

–40

Y5V

–60

–80 BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

–100

–50 –25 0 25 50 75

TEMPERATURE (°C)

100 125

1964 F03

Figure 3. Ceramic Capacitor Temperature Characteristics

VOUT

1mV/DIV

LT1964-5

100ms/DIV

COUT = 10µF

CBYP = 0.01µF

ILOAD = –200mA

1964 F04

Figure 4. Noise Resulting from Tapping on a Ceramic Capacitor

10

Thermal Considerations

The power handling capability of the device will be limited

by the maximum rated junction temperature (125°C). The

power dissipated by the device will be made up of two

components:

1. Output current multiplied by the input/output voltage

differential: IOUT • (VIN – VOUT), and

2. Ground pin current multiplied by the input voltage:

IGND • VIN.

The GND pin current can be found by examining the GND

Pin Current curves in the Typical Performance Character-

istics. Power dissipation will be equal to the sum of the two

components listed above.

The LT1964 series regulators have internal thermal limit-

ing designed to protect the device during overload condi-

tions. For continuous normal conditions the maximum

junction temperature rating of 125°C must not be

exceeded. It is important to give careful consideration to

all sources of thermal resistance from junction to ambient.

Additional heat sources mounted nearby must also be

considered.

For surface mount devices, heat sinking is accomplished

by using the heat spreading capabilities of the PC board

and its copper traces. Copper board stiffeners and plated

through-holes can also be used to spread the heat gener-

ated by power devices.

The following table lists thermal resistance for several

different board sizes and copper areas. All measurements

were taken in still air on 3/32" FR-4 board with one ounce

copper.

Table 1. Measured Thermal Resistance

COPPER AREA

TOPSIDE* BACKSIDE

2500mm2 2500mm2

1000mm2 2500mm2

225mm2 2500mm2

100mm2 2500mm2

50mm2 2500mm2

BOARD AREA

2500mm2

2500mm2

2500mm2

2500mm2

2500mm2

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

125°C/W

125°C/W

130°C/W

135°C/W

150°C/W

*Device is mounted on topside.

The thermal resistance junction-to-case (θJC), measured

at Pin 2, is 60°C/W.

1964f

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