2

LT1508

By using fixed high frequency PWM current averaging

without the need for slope compensation, the LT1508

achieves far lower line current distortion with a smaller

magnetic element than systems that use either peak

current detection, or zero current switching approach, in

both continuous and discontinuous modes of operation.

The LT1508 also provides filtering capability to reject line

switching noise which can cause instability when fed into

the multiplier. Line current dead zone is minimized with

low bias voltage at the current input to the multiplier. The

LT1508 provides many protection features including peak

current limiting and overvoltage protection. Implemented

with a very high speed process, the LT1508 can be

operated at frequencies as high as 300kHz.

Supply Voltage ........................................................ 27V

GTDR Current Continuous ...................................... 0.5A

GTDR Output Energy ................................................ 5

µJ

Operating Junction Temperature Range

LT1508C ................................................ 0

°C to 100°C

LT1508I ............................................ – 40

°C to 125°C

Thermal Resistance (Junction-to-Ambient)

N Package ................................................... 100

°C/W

SW Package ................................................ 120

°C/W

Consult factory for Military grade parts.

1

2

3

4

5

6

7

8

9

10

TOP VIEW

SW PACKAGE

20-LEAD PLASTIC SO WIDE

N PACKAGE

20-LEAD PDIP

20

19

18

17

16

15

14

13

12

11

GTDR1

GND2

GND1

GTDR2

SS1

SS2

OVP

ORDER PART

NUMBER

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Overall

q

0.25

0.45

mA

Supply Current On

11.5V

q

13

19

mA

q

15.5

16.5

17.5

V

q

9.5

10.5

11.5

V

Voltage Amplifier (PFC Section)

Voltage Amp Offset

q

–10

10

mV

Input Bias Current

q

– 25

– 250

nA

Voltage Gain

70

100

dB

Voltage Amp Unity-Gain Bandwidth

3

MHz

Voltage Amp Output High (Internally Clamped)

q

11.3

13.3

V

Voltage Amp Output Low

q

1.1

2

V

Voltage Amp Short-Circuit Current

q

3

8

17

mA

ELECTRICAL CHARACTERISTICS

LT1508CN

LT1508CSW

LT1508IN

LT1508ISW