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15

LT1010

1010fc

APPLICATIO  S I  FOR   ATIO

W

U

U

U

Typical thermal calculations for the miniDIP package are
detailed in the following paragraphs.

For 4.8mA supply current (typical at 50

°

C, 30V supply

voltage—see supply current graphs) to the LT1010 at

±

15V, P

D

 = power dissipated in the part is equal to:

(30V)(0.0048A) = 0.144W

The rise in junction is then:

(0.144W)(130

°

C/W—This is 

θ

JA

 for the N package)

= 18.7

°

C.

This means that the junction temperature in 50

°

C ambient

air without driving any current into a load is:

18.7

°

C + 50

°

C = 68.7

°

C

Using the LT1010 to drive 8V DC into a 200

 load using

±

15V power supplies dissipates P

D

 in the LT1010 where:

P

V

V

V

R

V

V

V

W

D

OUT

OUT

L

=

(

)

( )

=

(

)( )

=

+

.

15

8

8

200

0 280

This causes the LT1010 junction temperature to rise
another (0.280W)(0.130

°

C/W) = 36.4

°

C.

This heats the junction to 68.7

°

C + 36.4

°

C = 105.1

°

C.

Caution: This exceeds the maximum operating tempera-
ture of the device.

An example of 1MHz operation further shows the limita-
tions of the N (or miniDIP) package. For 

±

15V operation:

P

D

 at I

L

 = 0 at 1MHz* = (10mA)(30V) = 0.30W

This power dissipation causes the junction to heat from
50

°

C (ambient in this example) to 50

°

C + (0.3W)

(130

°

C/W) = 89

°

C. Driving 2V

RMS

 of 1MHz signal into a

200

 load causes an additional

P

V

W

D

=


⎝⎜


⎠⎟

( )

=

2

200

15 2

0 130

.

to be dissipated, resulting in another (0.130W)
(0.130

°

C/W) = 16.9

°

C rise in junction temperature to

89

°

C + 16.9

°

C = 105.9

°

C.

Caution: This exceeds the maximum operating tempera-
ture of the device.

Thermal Resistance of DFN Package

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. DFN Measured Thermal Resistance

COPPER AREA

THERMAL RESISTANCE

TOPSIDE

BACKSIDE

BOARD AREA

(JUNCTION-TO-AMBIENT)

2500 sq mm

2500 sq mm

2500 sq mm

40

°

C/W

1000 sq mm

2500 sq mm

2500 sq mm

45

°

C/W

225 sq mm

2500 sq mm

2500 sq mm

50

°

C/W

100 sq mm

2500 sq mm

2500 sq mm

62

°

C/W

For the DFN package, the thermal resistance junction-to-
case (

θ

JC

), measured at the exposed pad on the back of the

die, is 16

°

C/W.

Continuous operation at the maximum supply voltage and
maximum load current is not practical due to thermal
limitations. Transient operation at the maximum supply is
possible. The approximate thermal time constant for a
2500sq mm 3/32" FR-4 board with maximum topside and
backside area for one ounce copper is 3 seconds. This time
constant will increase as more thermal mass is added (i.e.
vias, larger board, and other components).

For an application with transient high power peaks, aver-
age power dissipation can be used for junction tempera-
ture calculations as long as the pulse period is significantly
less than the thermal time constant of the device and
board.

*See Supply Current vs Frequency graph.

Summary of Contents for LT1010

Page 1: ...h 75V s Slew Rate Drives 10V into 75 5mA Quiescent Current Drives Capacitive Loads 1 F Current and Thermal Limit Operates from Single Supply 4 5V Very Low Distortion Operation Available in 8 Pin miniD...

Page 2: ...20 mV VS 15V VIN 0V 20 100 mV IB Input Bias Current IOUT 0mA 0 250 A IOUT 150mA 0 500 A 0 800 A AV Large Signal Voltage Gain 0 995 1 00 V V ROUT Output Resistance IOUT 1mA 5 10 IOUT 150mA 5 10 12 Slew...

Page 3: ...e DD package for ambient temperatures above 25 C See Applications Information Note 3 In current limit or thermal limit input current increases sharply with input output differentials greater than 8V s...

Page 4: ...0 50 150 10 20 1010 G04 30 100 RL 100 TJ 25 C INPUT OUTPUT FREQUENCY MHz 0 1 1 OUTPUT IMPEDANCE 10 100 1 10 100 1010 G05 IBIAS 0 TJ 25 C FREQUENCY MHz 0 1 20 VOLTAGE GAIN dB 0 10 1 10 100 1010 G06 10...

Page 5: ...utput Noise Voltage TEMPERATURE C 50 0 997 GAIN V V 0 998 0 999 0 50 100 150 1010 G13 1 000 IOUT 0 VS 40V VS 4 5V TEMPERATURE C 50 0 OUTPUT RESISTANCE 4 8 0 50 100 150 1010 G14 12 2 6 10 IOUT 150mA FR...

Page 6: ...0 1 0 RL 50 f 10kHz VS 15V TC 25 C IBIAS 0 RBIAS 50 FREQUENCY kHz 1 0 4 HARMONIC DISTORTION 0 6 0 8 10 100 1000 1010 G21 0 2 0 IBIAS 0 VS 15V VOUT 10V TC 25 C RL 50 RL 100 Shorted Input Characteristic...

Page 7: ...84 2See electrical characteristics section for guaranteed limits The scheme is not perfect in that the rate of rise of sink current is noticeably less than for source current This can be mitigated by...

Page 8: ...st case over a range of supply voltages input voltage and temperature It would groundplaneisprudent especiallywhenoperatingathigh frequencies Thebufferslewratecanbereducedbyinadequatesupply bypass Wit...

Page 9: ...tions Parallel operation is not thermally unstable Should one unit get hotter than its mates its share of the output and its standby dissipation will decrease Asapracticalmatter parallelconnectionneed...

Page 10: ...ve loads is determined by RFCF Wideband Amplifiers This simple circuit provides an adjustable gain video amplifier that will drive 1VP P into 75 The differential pair provides gain with the LT1010 ser...

Page 11: ...rrent Sources A standard op amp voltage to current converter with a buffer to increase output current is shown here As usual A3 LT1010 A2 LT1010 R2 200 R1 50 R3 800 R4 39 R5 39 C1 20pF INPUT 1010 AI11...

Page 12: ...ent to A3 Supply Splitter Dual supply op amps and comparators can be operated fromasinglesupplybycreatinganartificialgroundathalf the supply voltage The supply splitter shown here can source or sink 1...

Page 13: ...ansfer function This circuit is somewhat similar except that the Q2 Q3 stage takes gain A2 DC stabilizes the input output path and A1 provides drive capability Feedback is to Q2 s emitter from A1 s ou...

Page 14: ...A 0 2V DIV B 0 2V DIV 1010 AI20 1010 AI21 Figures A and B show response with both output stages The LT1010 is used in Figure A Trace A input Trace B output Figure B uses the discrete stage and is slig...

Page 15: ...perating tempera ture of the device Thermal Resistance of DFN Package For surface mount devices heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper tra...

Page 16: ...output saturation voltage with no load Saturation Resistance The ratio of the change in output saturation voltage to the change in current producing it going from no load to full load Slew Rate The av...

Page 17: ...INCLUDE MOLD FLASH MOLD FLASH IF PRESENT SHALL NOT EXCEED 0 15mm ON ANY SIDE 5 EXPOSED PAD SHALL BE SOLDER PLATED 6 SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 0 3...

Page 18: ...5 3 302 0 127 020 0 508 MIN 018 003 0 457 0 076 120 3 048 MIN 1 2 3 4 8 7 6 5 255 015 6 477 0 381 400 10 160 MAX 008 015 0 203 0 381 300 325 7 620 8 255 325 035 015 0 889 0 381 8 255 NOTE 1 DIMENSIONS...

Page 19: ...T Package 5 Lead Plastic TO 220 Standard Reference LTC DWG 05 08 1421 U PACKAGE DESCRIPTIO T5 TO 220 0801 028 038 0 711 0 965 067 1 70 135 165 3 429 4 191 700 728 17 78 18 491 045 055 1 143 1 397 095...

Page 20: ...dback Amplifier 900V s Slew Rate Stable with Large Capacitive Loads LT1795 Dual 500mA 50MHz CFA 500mA IOUT ADSL Driver LT1886 Dual 700MHz 200mA Op Amp DSL Driver LINEAR TECHNOLOGY CORPORATION 1991 LT...

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