Ordering number : EN5268A Monolithic Linear IC LA7780M QPSK Downconverter for CATV Systems Overview Functions The LA7780M is a downconverter for QPSK data demodulation for digital CATV transmission. This IC integrates a preamplifier, an AGC amplifier, a mixer, an oscillator, a post-amplifier, and other circuits in a single chip, and provides all the functions required from cable signal input through output to the A/D converter. • • • • • • • Preamplifier AGC amplifier Mixer Oscillator Post amplifier IF AGC (internal/external) AGC detector Features Package Dimensions unit: mm 3108-MFP24D [LA7780M] 24 12 15.3 0.25 0.1 2.25 1 0.625 7.9 9.2 10.5 13 2.55max • Since a preamplifier is built in, the LA7780M has adequate sensitivity to handle the input signal from the cable directly. (Input signal level:–30 to +30 dBm) • Both internal and external AGC are supported as the AGC amplifier drive technique. • The output amplitude of the post amplifier used to drive the A/D converter is 2 Vp-p (typical). • Applications can be designed to use either a crystal or an inductor oscillator. 0.4 Specifications 1.27 0.67 SANYO: MFP24D Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Symbol Conditions Ratings Unit VCC max Pins 5, 6, and 17 7.0 V Circuit voltage V max Pins 4, 12, and 24 VCC V I4 The pin 4 output current 30 mA Circuit current I13 The pin 13 sink current 2 mA I16 The pin 16 sink current Allowable power dissipation Pd max Ta ≤ 70°C 2 mA 540 mW Operating temperature Topr –20 to +70 °C Storage temperature Tstg –55 to +150 °C Any and all SANYO products described or contained herein do not have specifications that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft’s control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO representative nearest you before using any SANYO products described or contained herein in such applications. SANYO assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all SANYO products described or contained herein. SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN D1698RM (OT) No. 5268-1/9 LA7780M Operating Conditions at Ta = 25°C Parameter Symbol Conditions Ratings Unit Recommended supply voltage VCC Pins 5, 6, and 17 5.0 V Operating supply voltage range VCC op Pins 5, 6, and 17 4.5 to 5.5 V AC Characteristics at Ta = 25°C, VCC = 5.0 V, internal AGC mode, Pin 24 is left open. Parameter Symbol Ratings Conditions min typ Circuit current Itotal Pins 4, 5, 6, and 17: no signal 64 RF input frequency range f(in) Pins 1, 8, and 9 30 Unit max 80 mA MHz 2.5 Vp-p IF output level VO(IF) Pin 13: *1 1.6 IF output IM3 VO(IM3) Pin 13: *2 40 dB BW Pin 13: *3 15 MHz IF output frequency bandwidth Local oscillator frequency range AGC amplifier input sensitivity AGC range f(LO) Pins 18, 19, 20, and 21 Vin(RF2) GR 30 Pins 8 and 9: *4 –25 –21 MHz –17 dBmV 60 80 –1 0 +1 19 21 AGC flatness ∆VO(IF) Preamplifier gain G(RF1) Pin 4: *5 17 Maximum preamplifier output level VOmax Pin 4: *6 50 VO(OSC) 200 Pin 13: IF output level < ±1 dB Pin 13: Compare with the state when Vin (RF2) = 30 dBmV Oscillator output level 2.0 95 150 Pin 23: The pin 23 frequency is 1/2 that of the local oscillator dB dB dB dBmV 500 800 1000 mVp-p Operating Modes Mode Pin 10 Pin 11 Pin 12 Internal AGC GND With a capacitor between pin 11 and ground Connected to pin 11 External AGC (Narrow control range: 3 to 5 V) GND (AGC divider inactive) With a capacitor between pin 11 and ground External AGC voltage supply Pin 12 = high impedance External AGC (Wide control range: 0 to 5 V) Open (AGC divider active) With a capacitor between pin 11 and ground External AGC voltage supply Pin 12 = low impedance (14 kΩ) Internal AGC External AGC Note: In internal AGC mode, the IF output level can be adjusted by varying the pin 24 DC voltage. Caution: Note 1. Input: SG = 69.55 MHz, 20 dBm V Other conditions: Internal AGC mode Pin 24 left open. Output: The post amplifier output (pin 13) at 5 MHz Transfer ratio = 1 : 1 No. 5268-2/9 LA7780M Note 2. Input: SG1 = 69.55 MHz, SG2 = 70.55 MHz Point Other conditions: Internal AGC mode Pin 24 left open. Output: The post amplifier output (pin 13) = 20 dBmV (69.55 MHz) + 20 dBmV (70.55 MHz) Note 3. Post amplifier output level = –3 dB Remove the low-pass filter between pins 14 and 16. (Short the coil of 27 µH and remove the capacitors of 27 pF and 15 pF.) Note 4. Input: SG1 = 69.55 MHz Other conditions: Internal AGC mode Pin 24 left open. Output: The signal level such that the post amplifier output (pin 13) falls by –3 dB. Note 5. SG = 75 MHz, 20 dBm V Note 6. SG1 = 75 MHz, SG2 = 76 MHz, Adjust the pin 1 level until the IM3 in the pin 4 output is 40 dB. Output:RF1-OUT (pin 4) VO(IM3) = 40 dB No. 5268-3/9 LA7780M Pin Assignment Top view Usage Notes • The oscillator may stop if the power supply rise time is extremely short. To prevent this problem, insert a 500 kΩ resistor between pin 18 and ground or between pin 21 and ground. (This applies when a crystal oscillator is used.) • This IC should be used with the pin 13 output level between 1 Vp-p and 2 Vp-p. • Use a low-pass filter with a 6-dB attenuation between pins 14 and 16. • Since the high-frequency process is adopted, care must be taken to prevent the influence of static electricity. Block Diagram No. 5268-4/9 LA7780M Pin Descriptions Pin No. Function Pin voltage (V) Note 1 RF1 input 2.8 2 RF gain 1.3 3 GND 0 4 RF1 output Open collector 5 VCC 5.0 6 VCC 5.0 7 GND 0 8 RF2 input (1) 2.5 V = 2.5 V 9 RF2 input (2) 2.5 R = 1 kΩ Internal/external 0 (GND) AGC switch 1.0 (open) 11 AGC filter 2 Open collector I1 = 20 µA 12 AGC filter 1 Open base (Pin 10 → GND) 4.0 (Pin 10 open) I2 = 100 µA 10 Equivalent circuit Impedance connected to pin 2 must be > 45 Ω Pin 10 → GND : Internal or external AGC (narrow control range) Pin 10 → open : External AGC (wide control range) I3, I4 & Q1 are switched on and off by pin 10. Continued on next page. No. 5268-5/9 LA7780M Continued from preceding page. Pin No. Function Pin voltage (V) 13 Post-amp output 2, 3 14 Post-amp input 2.0 15 GND 0 16 IF output 1.7 17 VCC 5.0 18 Oscillator input 4 3.0 19 Oscillator input 3 20 Oscillator input 2 21 Oscillator input 1 3.0 22 GND 0 23 Divider output 3.3 24 Output level adjustment 2.5 Note Equivalent circuit R = 30 Ω I = 7 mA V = 2.1 V R = 300 Ω R = 100 Ω I = 3.5 mA V = 3.0 V R = 5 kΩ I = 1 mA R = 100 Ω I = 1 mA R = 25 kΩ No. 5268-6/9 LA7780M Test Circuit No. 5268-7/9 *: The choke coil between pins 19 and 20 is not required if the fundamental frequency of the crystal (not an overtone) is used. LA7780M Sample Application Circuit No. 5268-8/9 LA7780M Specifications of any and all SANYO products described or contained herein stipulate the performance, characteristics, and functions of the described products in the independent state, and are not guarantees of the performance, characteristics, and functions of the described products as mounted in the customer’s products or equipment. To verify symptoms and states that cannot be evaluated in an independent device, the customer should always evaluate and test devices mounted in the customer’s products or equipment. SANYO Electric Co., Ltd. strives to supply high-quality high-reliability products. However, any and all semiconductor products fail with some probability. It is possible that these probabilistic failures could give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire, or that could cause damage to other property. When designing equipment, adopt safety measures so that these kinds of accidents or events cannot occur. Such measures include but are not limited to protective circuits and error prevention circuits for safe design, redundant design, and structural design. In the event that any or all SANYO products (including technical data, services) described or contained herein are controlled under any of applicable local export control laws and regulations, such products must not be exported without obtaining the export license from the authorities concerned in accordance with the above law. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or any information storage or retrieval system, or otherwise, without the prior written permission of SANYO Electric Co., Ltd. Any and all information described or contained herein are subject to change without notice due to product/technology improvement, etc. When designing equipment, refer to the “Delivery Specification” for the SANYO product that you intend to use. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of October, 1998. Specifications and information herein are subject to change without notice. PS No. 5268-9/9