7

FN7015.2

March 26, 2007

Applications Information

Product Description

The EL1509 is a dual operational amplifier designed for

customer premise line driving in DMT ADSL solutions. It is a

dual current mode feedback amplifier with low distortion

while drawing moderately low supply current. It is built using

Elantec's proprietary complimentary bipolar process and is

offered in industry standard pin-outs. Due to the current

feedback architecture, the EL1509 closed-loop 3dB

bandwidth is dependent on the value of the feedback

resistor. First the desired bandwidth is selected by choosing

Typical Performance Curves section show the effect of

dependent on the power supply voltage.

Power Supply Bypassing and Printed Circuit

Board Layout

As with any high frequency device, good printed circuit

board layout is necessary for optimum performance. Ground

plane construction is highly recommended. Lead lengths

should be as short as possible, below ¼”. The power supply

pins must be well bypassed to reduce the risk of oscillation.

A 1.0µF tantalum capacitor in parallel with a 0.01µF ceramic

capacitor is adequate for each supply pin.

For good AC performance, parasitic capacitances should be

kept to a minimum, especially at the inverting input. This

implies keeping the ground plane away from this pin. Carbon

resistors are acceptable, while use of wire-wound resistors

should not be used because of their parasitic inductance.

Similarly, capacitors should be low inductance for best

performance.

FIGURE 25. TRANSIMEDANCE vs TEMPERATURE

FIGURE 26. PACKAGE POWER DISSIPATION vs AMBIENT

TEMPERATURE

FIGURE 27. PACKAGE POWER DISSIPATION vs AMBIENT

TEMPERATURE

Typical Performance Curves

3

0

2

1

0.5

1.5

2.5

TEMPERATURE (°C)

-50

100

150

-25

0

50

125

25

75

JEDEC JESD51-3 AND SEMI G42-88 (SINGLE

LAYER) TEST BOARD

0.9

0

AMBIENT TEMPERATURE (°C)

0.2

0.8

0.4

0.6

0.1

0.3

0.5

0.7

0

150

50

100

125

25

75 85

SO

8

&

DF

N8

16

0°C

/W

781mW

JEDEC JESD51-7 HIGH EFFECTIVE THERMAL

CONDUCTIVITY (4-LAYER) TEST BOARD (DFN EXPOSED

DIEPAD SOLDERED TO PCB PER JESD51-5)

3.5

3

0

AMBIENT TEMPERATURE (°C)

0150

50

100

2

2.5

1

1.5

0.5

125

25

75 85

DF

N8

43

°C

/W

SO8

110°C

/W

2.907W

1.136W

EL1509