Absolute Maximum Ratings

If MilitaryAerospace specified devices are required

please contact the National Semiconductor Sales

OfficeDistributors for availability and specifications

20V

Power Dissipation (note 1)

1300 mW

Operating Temperature

b

Storage Temperature

b

Lead Temp (Soldering 10 seconds)

260 C

Symbol

Parameter

Pin(s)

Conditions

Min

Typ

Max

Units

Supply Current

13

Zero Input Frequency

65

mA

(See

Figure 1 )

Regulator Voltage

11

81

85

89

V

Regulator Output Resistance

11

135

X

Reference Voltage

4

19

21

23

V

Reference Output Resistance

4

53

kX

Norton Amplifier Mirror Gain

5 6

09

10

11

NPN Transistor DC Gain

9 10

125

Function Generator Feedback

1

10

mA

Bias Current

Drive Voltage Extremes

2 12

g

4

g

45

V

Sine and Cosine

Sine Output Voltage

2

b

350

0

a

350

mV

with Zero Input

Function Generator Linearity

g

17

%FSD

k

Function Generator Gain

5075

5375

5675

V

Note 1

For operation above 25 C the LM1819 must be derated based upon a 125 C maximum junction temperature and a thermal resistance of 76 CW which

applies for the device soldered in a printed circuit board and operating in a still-air ambient

Application Hints

AIR-CORE METER MOVEMENTS

Air-core meters are often favored over other movements as

a result of their mechanical ruggedness and their indepen-

dence of calibration with age A simplified diagram of an air-

core meter is shown in

Figure 2 There are three basic

pieces a magnet and pointer attached to a freely rotating

axle and two coils each oriented at a right angle with re-

spect to the other The only moving part in this meter is the

axle assembly The magnet will tend to align itself with the

vector sum of H fields of each coil where H is the magnetic

field strength vector If for instance a current passes

through the cosine coil (the reason for this nomenclature

will become apparent later) as shown in

Figure 3(a) the

magnet will align its magnetic axis with the coil’s H field

Similarly a current in the sine coil (

Figure 3(b) ) causes the

magnet to align itself with the sine H field If currents are

applied simultaneously to both sine and cosine coils the

magnet will turn to the direction of the vector sum of the two

H

fields

(Figure 3(c)) H is proportional to the voltage applied

to a coil Therefore by varying both the polarity and magni-

tude of the coil voltages the axle assembly can be made to

rotate a full 360 The LM1819 is designed to drive the me-

ter through a minimum of 305

TLH5263 – 2

FIGURE 2 Simplified Diagram of an Air Core Meter

2