Datasheet

MAX3964A/MAX3968
+3.0V to +5.5V, 125Mbps to 266Mbps
Limiting Amplifiers with Loss-of-Signal Detector
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Pin Description
PIN
QSOP
THIN
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.
Connect to V
CC
to enable squelching.
2
20
V
TH
Output of Internal Op Amp that Sets Loss-of-Signal Threshold Voltage (Figure 1). Connect a
resistor from V
TH
to INV and from INV to ground (minimum resistance 100kΩ) to program the
desired threshold voltage.
3 1 INV
Inverting Input of Internal Op Amp that Sets Loss-of-Signal Threshold Voltage (Figure 1).
Connect a resistor from V
TH
to INV and from INV to ground (minimum resistance 100kΩ) to
program the desired threshold voltage.
4 2 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
capacitor from FILTER to V
CC
for proper operation.
5 3 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.
6 4 IN- Inverting Data Input
7 5 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 V
CCO
Output Buffer Supply Voltage. Connect to the same potential as V
CC
, but filter V
CCO
and V
CC
separately.
14 12 OUT+ Noninverting PECL Data Output. Terminate with 50Ω to (V
CC
- 2V).
15 13 OUT- Inverting PECL Data Output. Terminate with 50Ω to (V
CC
- 2V).
16 14 LOS-
Inverting Loss-of-Signal Output. LOS- is asserted low when input power drops below the LOS
threshold. This pin is PECL compatible and should be terminated with 50Ω to (V
CC
- 2V).
17 15 LOS+
Noninverting Loss-of-Signal Output. LOS+ is asserted high when input power drops below the
LOS threshold. This pin is PECL compatible and should be terminated with 50Ω to (V
CC
- 2V).
18 16 V
CCO
MAX3964A/MAX3968: This pin can be left open or connected to the positive supply.
19, 20
17, 18
V
CC
+3.0V to +5.5V Supply Voltage
—EP
Exposed
Pad
Connect the exposed pad to board ground for optional electrical and thermal performance.