Data Sheet

ADA4310-1

Rev. C | Page 11 of 14

APPLICATIONS INFORMATION

FEEDBACK RESISTOR SELECTION

The feedback resistor has a direct impact on the closed-loop

bandwidth and stability of the current feedback op amp.

Reducing the resistance below the recommended value can

make the amplifier response peak and even become unstable.

Increasing the size of the feedback resistor beyond the recom-

mended value reduces the closed-loop bandwidth. Table 6

provides a convenient reference for quickly determining the

feedback and gain resistor values, and the corresponding

bandwidth, for common gain configurations. The recommended

value of feedback resistor for the ADA4310-1 is 499 Ω.

Gain

−3 dB SS BW (MHz)

+2

499

499

230

+5

499

124

190

+5

1k

249

125

+10

499

55.4

160

+20

499

26.1

115

1

POWER CONTROL MODES OF OPERATION

The ADA4310-1 features four power modes: full power, ¾

power, ½ power, and shutdown. The power modes are

controlled by two logic pins, PD0 and PD1. The power-down

control pins are compatible with standard 3 V and 5 V CMOS

logic. Table 7 shows the various power modes and associated

logic states. In the power-down mode, the output of the

amplifier goes into a high-impedance state.

Table 7. Power Modes

PD1

PD0

Power Mode

Total Supply

Current (mA)

Output

Impedance

Low

Low

Full Power

15.2

Low

Low

High

¾ Power

11.2

Low

High

Low

½ Power

7.8

Low

High

High

Power Down

1.3

High

EXPOSED THERMAL PAD CONNECTIONS

The exposed thermal pad on the 10-lead MSOP package is both

the reference for the PD pins and the only electrical connection

for the negative supply voltage. Therefore, in the 10-lead MSOP

package, the ADA4310-1 can only be used on a single supply.

The exposed thermal pad MUST be connected to ground.

Failure to do so will render the part inoperable.

The 4 mm × 4 mm 16-lead LFCSP package has dedicated pins

for both the positive and negative supplies, and it can be used

in either single supply or dual supply applications. There is no

electrical connection for the exposed thermal pad. Although the

pad could theoretically be connected to any potential, it is still

typically connected to ground.

A requirement for both packages is that the thermal pad be

connected to a solid plane with low thermal resistance, ensuring

adequate heat transfer away from the die and into the board.

POWER LINE APPLICATION

Applications (that is, powerline AV modems) requiring greater

than 10 dBm peak power should consider using an external line

driver, such as the ADA4310-1. Figure 21 shows an example

interface between the TxDAC® output and ADA4310-1 biased

for single-supply operation. The TxDAC’s peak-to-peak differ-

ential output voltage swing should be limited to 2 V p-p, with

the ADA4310-1s gain configured to realize the additional

voltage gain required by the application. A low-pass filter

should be considered to filter the DAC images inherent in the

signal reconstruction process. In addition, dc blocking capacitors

are required to level-shift the TxDAC’s output signal to the

common-mode level of the ADA4310-1 (that is, AVDD/2).

0.1µF

IOUTP+

IOUTP–

0dB TO –7.5dB

OPTIONAL

LCLPF

AVDD/2

ADA4310-1

ADA4310-1

1/2

1/2

TxDAC

Figure 21. TxDAC Output Directly via Center-Tap Transformer