LT1249

5

TEMPERATURE (

°C)

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

1249 G11

75

–25

25

125

–50

0

50

100

Synchronization Threshold

Voltage Amp Sink Current Limits

(Threshold)

–2.4

–1.2

0

1.2

1.0

0.8

0.6

0.4

0.2

0

–0.2

–0.4

–0.6

–0.8

–1.0

1249 G12

1.2

2.4

125

°C

25

°C

–50

°C

TEMPERATURE (

°C)

1249 G15

–1.30

–1.25

–1.20

–1.15

–1.10

–1.05

–1.00

–0.95

–0.90

–75

–25

–50

25

0

50

100

75

125

Maximum Multiplier Output

Transconductance of Current

Amplifier Over Temperature

TEMPERATURE (

°C)

–50

100

1249 G13

050

400

350

300

250

200

150

100

50

0

–25

25

75

125

Maximum Duty Cycle

TEMPERATURE (

°C)

100

99

98

97

96

95

94

93

92

91

90

1249 G16

75

–25

25

125

–50

0

50

100

TEMPERATURE (

°C)

–75

–25

–50

25

0

50

100

75

125

1249 G14

60

50

40

30

20

10

0

UP THRESHOLD

DOWN THRESHOLD

NOTE: THESE SINK CURRENT THRESHOLDS ARE

FOR OVERVOLTAGE PROTECTION FUNCTION.

GND (Pin 1): Ground.

that senses and forces the line current to follow the

reference signal that comes from the multiplier by com-

the modulator has zero duty cycle.

and it is limited to 1.1V. The noninverting input of the

is normally at negative potential and only AC signals

appear at the noninverting input of the current amplifier.

multiplier. It is a current input that is biased at 2V to

minimize the crossover dead zone caused by low line

voltage. A 32k resistor is in series with the current input,

so that a small external capacitor can be used to filter out

the switching noise from the high impedance lines.

amplifier. The output is clamped at 12V. When the output

goes below 1.5V, the multiplier output current is zero.