MAX3505 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – Upstream CATV Amplifier

19-2351; Rev 0; 4/02
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Upstream CATV Amplifier
General Description
The MAX3505 programmable power amplifier is
designed for use in CATV upstream applications. The
MAX3505 drives 64dBmV (QPSK) into a 75Ω load when
driven with a 34dBmV nominal input signal. Both input
and output ports are differential, requiring that an exter-
nal balun be used at the output port. The variable gain
feature provides greater than 56dB of dynamic range,
which is controlled by an SPI™ 3-wire interface. Gain
control is available in 0.5dB steps. The device operates
over a frequency range of 5MHz to 65MHz. The
MAX3505 is internally matched for use with a 1:1 balun.
This device operates from a single 5VDC supply and
draws 285mA during transmit (100% duty cycle,
64dBmV out). The bias current is automatically adjust-
ed based on the output level to increase efficiency.
Additionally, the device can be disabled between
bursts to minimize noise and save power while still
maintaining a match at the output port. In addition, a
shutdown mode is available to disable all circuitry and
reduce current consumption to 5µA (typ).
The MAX3505 is available in a 20-pin QFN package.
The device operates in the extended industrial temper-
ature range (-40°C to +85°C).
Applications
DOCSIS/EuroDOCSIS and DVB Cable
Modems
OpenCable Set-Top Box
Telephony Over Cable
CATV Status Monitor
SPI is a trademark of Motorola, Inc.
DOCSIS/EuroDOCSIS/OpenCable are trademarks of CableLabs.
Typical Operating Circuit
CONTROL
LOGIC
10
SHDN
9
TXEN
0.001µF
+
2
IN+
15
VCC
OUT+ ¹⁴
0.1µF
5V
1:1
ANTI-ALIAS
INPUT
FILTER
-
+5V
0.1µF
4
IN-
0.001µF
1 _VCC
4 _GND
5V
MAX3505
12
OUT-
0.1µF
16
CEXT
0.1µF
GND ⁵
6
SDA
7
SCLK
8
CS
CONTROL
LOGIC
OUTPUT
Features
o Single 5V Supply Operation
o Accurate Gain Control, ±1dB over 56dB Range
o Gain Programmable in 0.5dB Steps
o -55dBc Harmonic Distortion at 65MHz
o Low Burst On/Off Transient
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX3505EGP -40°C to +85°C 20 QFN-EP* (5mm × 5mm)
*EP = exposed pad
TOP VIEW
V_{CC 1}
IN+ 2
GND 3
IN- 4
GND 5
Pin Configuration
MAX3505
15 V_CC
14 OUT+
13 N.C.
12 OUT-
11 N.C.
QFN**
**NOTE: THE EXPOSED PAD MUST BE SOLDERED TO GROUND.
________________________________________________________________ Maxim Integrated Products 1
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