RC2798G Fairchild Semiconductor, RC2798G Datasheet

Up-Down Converters TSSOP-20

RC2798G

Manufacturer Part Number
RC2798G
Description
Up-Down Converters TSSOP-20
Manufacturer
Fairchild Semiconductor
Type
Frequency Down Converterr
Datasheet

Specifications of RC2798G

Mounting Style
SMD/SMT
Operating Supply Voltage
5 V
Maximum Operating Temperature
+ 75 C
Minimum Operating Temperature
- 40 C
Package / Case
TSSOP-20
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Features
• RF input frequency range 30 to 250MHz
• On chip VCO with LO frequency range 30 to 250MHz
• IF amplifier with AGC setting
• High dynamic range -9dBm IIP3
• On chip Video Amplifier
• Built in ESD protection
• Supply voltage range 5 to 10 V
• Space saving 20-Lead TSSOP package
Applications
• Digital Set-top receivers
• Cable modems
• Internet surfboards
• Network Interface Modules
• Multimedia PCs
Block Diagram
PRELIMINARY INFORMATION describes products that are not in full production at the time of printing. Specifications are based on design goals
and limited characterization. They may change without notice. Contact Fairchild Semiconductor for current information.
RC2798
Integrated QAM IF Downconverter
OSC_OUT
AGC_IN1
AGC_IN2
VCC MIX
VAGC
GND
C1
C2
B2
B1
10
1
2
3
4
5
6
7
8
9
LO
AGC + MIX
RC2798
Description
The RC2798 is an integrated solution for the down-
conversion of QAM IF signals in the front-end design of
cable modem and set-top receivers. It is intended for use in
64QAM and 256QAM IF downconversion applications.
The RC2798 integrates IF amplifier with AGC , mixer, VCO,
and a video amplifier on a single chip. It accepts the QAM IF
signals via SAW filter and downconverts it to 5MHz
baseband signal.
The baseband signal can be digitized using Fairchild
Semiconductor’s 8 bit A/D (TMC1175 series) or 10bit A/D
(TMC1185 series) and decoded further with a QAM
demodulator. The IF, Oscillator and Mixer section work at
5V. The video amplifier works at 5V to 10V. The RC2798 is
available in a 20 Lead TSSOP package.
VideoAmp
20
19
18
17
16
15
14
13
12
11
GND
MIX_OUT2
MIX_OUT1
G1A
G1B
VampIn1
VampIn2
VccAmp
OUT1
OUT2
www.fairchildsemi.com
Rev 1.0.0

Related parts for RC2798G

RC2798G Summary of contents

Page 1

... C2 B1 PRELIMINARY INFORMATION describes products that are not in full production at the time of printing. Specifications are based on design goals and limited characterization. They may change without notice. Contact Fairchild Semiconductor for current information. Description The RC2798 is an integrated solution for the down- conversion of QAM IF signals in the front-end design of cable modem and set-top receivers ...

Page 2

RC2798 Absolute Maximum Ratings Parameter Video Amplifier 5V Operation Vcc_Mix Supply voltage 1 (for AGC amplifier, oscillator, and mixer) VccVamp Supply voltage 2 ( for video amplifier) P Power dissipation D T Operation temperature range A Tstg Storage temperature range ...

Page 3

PRODUCT SPECIFICATION Electrical Characteristics Parameter AGC Amplifier, Oscillator, and Mixer Blocks (Vcc = 5V) Icc1 Supply current input frequency range RF f OSC frequency range OSC f IF output frequency range IF CG Maximum conversion gain MAX ...

Page 4

RC2798 Typical Characteristics -10 0 5.00 E-01 4.50E-02 4.00E-02 3.50E-02 3.00E-02 2.50E-02 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 -5.00E-03 0 4.00 8.00 1.2 1.6 E-01 E- 1.5 2 2.5 3 3.5 ...

Page 5

PRODUCT SPECIFICATION 10nF AGC_IN1 RF input AGC_IN2 51 10nF 10K VAGC (1.0–4.0V) 10K 0.22µF Vcc_Mix(+5V) FB VCC MIX + 0.1µF + 0.1µF 10µF 10µF OSC_OUT 10nF Oscillator O/P 10nF Ext. LO I/P 10nF 51 Figure 3. Measurement Circuit 1—AGC + ...

Page 6

RC2798 AGC_IN1 1 AGC_IN2 2 VAGC 3 VCC MIX 4 OSC_OUT 5 GND Figure 4. Measurement Circuit 2—Video Amplifier Block 6 RC2798 GND 20 MIX_OUT2 19 AGC + MIX MIX_OUT1 ...

Page 7

PRODUCT SPECIFICATION Applications Discussion GND Figure 5. Application Circuit RC2798 7 ...

Page 8

RC2798 Crystal Oscillator Implementation + .1µF + .1µF 10µF 10µF Oscillator O/P 220pF XTL 38.886 MHz Fundamental mode Series Resonant Figure 6. Fundamental Mode—Series Resonant XTL + .1µF .1µF 10µF 10µF Oscillator O/P 220pF XTL ...

Page 9

PRODUCT SPECIFICATION Overtone Mode—Series Resonant XTL desired to operate a XTL at non-fundamental or overtone frequency coupled parallel resonant network should be connected to feedback input pin, B1. The typical impedance looking into B1 with ...

Page 10

RC2798 + .1µF 10µF Oscillator O/P XTL 38.886 MHz Parallel Resonant Cc: 15pF for Fundamental 2pF for Overtone Figure 9. Fundamental or Overtone Mode with Improved Duty Cycle—Parallel Resonant XTL 10 RC2798 AGC_IN1 1 AGC_IN2 2 VAGC 3 ...

Page 11

PRODUCT SPECIFICATION Package Dimensions 20-pin TSSOP package Inches Millimeters Symbol Min. Max. Min. A — .047 — A1 .002 .006 0.05 A2 .031 .041 0.80 B .007 0.19 .012 C .004 .008 0.09 D .250 .257 6.40 E .240 .264 ...

Page 12

... RC2798 Ordering Information Product Number Package RC2798G 20 pin TSSOP LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems ...

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