+3.0V to +5.5V, 125Mbps to 266Mbps

Limiting Amplifiers with Loss-of-Signal Detector

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5

Pin Description

PIN

QSOP

QFN

NAME

FUNCTION

1

19

SQUELCH

Squelch Input. The squelch function disables the data outputs by forcing OUT- low and OUT+

high during a loss-of-signal condition. Connect to GND or leave unconnected to disable.

2

20

Output of Internal Op Amp that Sets Loss-of-Signal Threshold Voltage (Figure 1). Connect a

Ω) to program the

desired threshold voltage.

31

INV

Inverting Input of Internal Op Amp that Sets Loss-of-Signal Threshold Voltage (Figure 1).

Ω) to

program the desired threshold voltage.

42

FILTER

Filter Output of Full-Wave Logarithmic Detectors (FWDs). The FWD outputs are summed

together at FILTER to generate the received-signal-strength indicator (RSSI). Connect a

53

RSSI

Received-Signal-Strength Indicator Output. The analog DC voltage at RSSI indicates the input

signal power. The RSSI output is reduced approximately 120mV when LOS+ is asserted.

64

IN-

Inverting Data Input

75

IN+

Noninverting Data Input

8—

SUB

Substrate. Connect to ground.

9, 10

6, 7, 8

GND

Ground

11

9

CZP

Auto-Zero Capacitor Input. Connect a capacitor between CZP and CZN to determine the offset-

correction-loop bandwidth.

12

10

CZN

Auto-Zero Capacitor Input. Connect a capacitor between CZP and CZN to determine the offset-

correction-loop bandwidth.

13

11

separately.

14

12

OUT+

Noninverting PECL Data Output. Terminate with 50

15

13

OUT-

Inverting PECL Data Output. Terminate with 50

16

14

LOS-

Inverting Loss-of-Signal Output. LOS- is asserted low when input power drops below the LOS

threshold. For the MAX3964/MAX3968, this pin is PECL compatible and should be terminated

with 50

termination.

17

15

LOS+

Noninverting Loss-of-Signal Output. LOS+ is asserted high when input power drops below the

LOS threshold. For the MAX3964/MAX3968, this pin is PECL compatible and should be

terminated with 50

require termination.

MAX3964/MAX3968: This pin can be left open or connected to the positive supply.

18

16

GNDO

MAX3965: This pin must be connected to ground.

19, 20

17, 18

+3.0V to +5.5V Supply Voltage

—EP

Exposed

Pad

Connect the exposed pad to board ground for optional electrical and thermal performance.