MAX3768CUB-T Maxim Integrated, MAX3768CUB-T Datasheet - Page 10

• Manufacturer Part Number: MAX3768CUB-T
• Description: Limiting Amplifiers 3-5.5V 1.25/2.5Gbps
• Manufacturer: Maxim Integrated

Specifications of MAX3768CUB-T

• Operating Supply Voltage: 5 V
• Supply Current: 39 mA
• Operating Temperature Range: + 70 C
• Package / Case: uMAX EP
• Mounting Style: SMD/SMT
• Number Of Channels: 1
• Power Dissipation: 1600 mW

+3.0V to +5.5V, 1.25Gbps/2.5Gbps
Limiting Amplifiers
Figure 3 is a functional diagram of the MAX3264/
MAX3265/MAX3268/MAX3269/MAX3765/MAX3768 lim-
iting amplifiers. A linear input buffer drives a multistage
limiting amplifier and an RMS power-detection circuit.
Offset correction with lowpass filtering ensures low
deterministic jitter. The output buffer produces a limited
output signal. The MAX3264/MAX3265/MAX3765 pro-
duce a CML output, while the MAX3268/MAX3269/
MAX3768 produce a PECL-compatible output signal.
Schematics of these input/output circuits are shown in
Figures 4 through 7.
Figure 3. Functional Diagram
10
_______________Detailed Description
______________________________________________________________________________________
IN+
IN-
TOTAL GAIN = 55dB (MAX3264/MAX3268/MAX3768)
TOTAL GAIN = 49dB (MAX3265/MAX3269/MAX3765)
100Ω
MAX3264
MAX3265
MAX3268
MAX3269
MAX3765
MAX3768
BUFFER
INPUT
CORRECTION
OFFSET
POWER DETECT
COMPARATOR
WITH
TH
CAZ1
R
R
LOS
LOS
GAIN
100pF
LOW-
PASS
= 8kΩ (MAX3265/MAX3269/MAX3765)
= 16kΩ (MAX3264/MAX3268/MAX3768)
CAZ2
An RMS power detector looks at the signal from the
input buffer and compares it to a threshold set by the
TH resistor (see Typical Operating Characteristics for
appropriate resistor values). The signal-detect informa-
tion is provided to the LOS outputs, which are internally
terminated with 8kΩ (MAX3265/MAX3269/MAX3765) or
16kΩ (MAX3264/MAX3268/MAX3768) pullup resistors.
The LOS outputs meet TTL voltage specifications when
loaded with a resistor ≥ 4.7kΩ.
TTL
TTL
CONTROL
OUTPUT
BUFFER
V
V
CC
CC
RMS Power Detect with
Loss-of-Signal Indicator
R
R
LOS
LOS
LOS
LOS
OUT+
OUT-
SQUELCH
LEVEL