SCD4480-DFI Rev B 2/27/2013

10

Aeroflex Plainview

ACT4480 Power Dissipation

Total Power Input

The ACT4480-DFI uses ±15 Volt supplies and a +5 Volt supply.

Total Input Power: Channel A transmitting, Channel B in standby

Conditions

Supply Voltages

Supply Current

(100% Duty Cycle)

Power

CH_A: Transmitting at 30vpk-pk into a

243

Ω load resistance.

Transmitter inhibited)

+15 Volts

76mA

1.140 Watts

-15 Volts

93mA

1.395 Watts

+5 Volts

33mA

0.165 Watts

Total Power

2.700 Watts

Total Input Power: Channel A and Channel B in standby

Conditions

Supply Voltages

Supply Current

(100% Duty Cycle)

Power

CH_A: Standby (Receive mode,

Transmitter inhibited)

CH_B: Standby (Receive mode,

Transmitter inhibited)

+15 Volts

12mA

0.180 Watts

-15 Volts

30mA

0.450 Watts

+5 Volts

31mA

0.155 Watts

Total Power

30.0Vpk-pk, line to line, measured across RLoad

RLoad:

34 + 34 + 175

= 243

Ω

15.0Vpk / 243 Ohms

= 61.73mApk

Instantaneous Power:

15.0V * 61.73mA

= 926mWatts (960mW measured)

Average Power

= 569mW

Total Hybrid Power Dissipation:

2.7W

– 569mW

= 2.131 Watts

Θjc

= 3.02°C/W (Calculated)

Junction Temperature Rise over Case

CH_A Die Transmitting = 2.131 x 3.02°C/W = 6.40°C

Junction Temperature Rise over Case

CH_B Die Standby

= 0.785 x 3.02°C/W = 2.37°C