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Texas Instruments SN761678DBT
- Part No.:
- SN761678DBT
- Manufacturer:
- Texas Instruments
- Category:
- Video Processing
- Package:
- -
- Datasheet:
-
SN761678DBT.pdf
- Description:
- TV/VCR TUNER MOP IC
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Product details
Overview
SN761678DBT from Texas Instruments is a single-chip TV tuner IC integrating a three-band local oscillator (VHF-LOW, VHF-HIGH, UHF), mixer, PLL synthesizer, 30-V tuning voltage amplifier, and four NPN band-switch drivers. It operates from a 5-V supply, supports I²C bus control, and delivers typical conversion gain of 25 dB and noise figure of 9.5 dB across VHF/UHF bands for terrestrial/analog TV signal reception.
For engineers reviewing the SN761678DBT datasheet, SN761678DBT pinout, SN761678DBT application, or SN761678DBT equivalent, this device serves as a complete RF-to-IF downconversion solution requiring external 4-MHz crystal and passive IF filter - critical for legacy TV, set-top box, and VCR/DVD recorder tuner designs where integrated PLL control and multi-band switching are essential.
Technical Context
The SN761678DBT implements a 15-bit programmable counter with selectable reference divider ratios (512/640/1024) to generate precise local oscillator frequencies from a 4-MHz crystal input. Its PLL architecture includes a charge-pump output (CP) with configurable current (60 µA or 280 µA) and phase detector driving prescalers (1/8, 1/32, or 1/33) for VHF/UHF band coverage up to 804 MHz.
It integrates dual IF amplifier paths (IF IN1/IN2, MIX OUT1/MIX OUT2) supporting independent signal processing, while four NPN band-switch drivers (BS1–BS4) provide emitter-follower outputs (3.5 V @ 10 mA) to control external RF front-end filters and amplifiers - enabling seamless band selection between VHF-LOW (58 MHz), VHF-HIGH (136 MHz), and UHF (804 MHz) channels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5-V system rails; absolute max 6.5 V |
| Tuning Voltage Output | 0.4 V to 33 V - 30-V capable VTU pin drives varactor diodes in external VCO circuits |
| Crystal Frequency | 4 MHz nominal (3.2–4.48 MHz range) - enables stable PLL reference with external 4-MHz crystal |
| I²C Interface | Standard-mode (100 kHz) and fast-mode (400 kHz) support - bidirectional SDA/SCL for register programming |
| Operating Temperature | –20°C to +85°C - qualified for consumer electronics environments including STBs and TVs |
| Conversion Gain | 25 dB typical (VHF/UHF bands) - sufficient for direct connection to downstream IF amplifiers without gain staging |
| Noise Figure | 9.5 dB (VHF-LOW), 11 dB (UHF) - meets analog TV signal-to-noise requirements at antenna input |
Pinout & Package
SN761678DBT is housed in a 30-pin Thin Shrink Small-Outline Package (TSSOP), DBT package drawing, with 0.65-mm lead pitch and exposed thermal pad (not electrically connected). Pin numbering follows top-view layout per TI SLES185.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4, 5 | VHI/VLO OSC C/B | Collector/base connections for VHF HIGH/LOW oscillator transistors - require external tank components |
| 6–9 | UHF OSC B1/C1/C2/B2 | Dual-base/dual-collector UHF oscillator terminals - enable wideband UHF tuning up to 804 MHz |
| 10, 27 | IF GND / RF GND | Separate ground returns for IF and RF sections - minimize coupling and preserve noise performance |
| 11 | VCC | Main 5-V supply for mixer, oscillator, PLL, and band switches - bypassing required per layout guidelines |
| 12 | IF OUT | Differential-capable IF output - connects to external 43-MHz IF filter before IF amplifier stage |
| 13 | CP | Charge-pump output - drives loop filter to control VCO frequency; current selectable via I²C |
| 14 | VTU | 30-V tuning voltage amplifier output - directly biases varactor diodes in external VHF/UHF oscillators |
| 15 | XTAL | 4-MHz crystal input - ac-coupled with 0.1-µF capacitor; internal oscillator circuit requires 25–300 Ω crystal ESR |
| 16, 17 | SCL, SDA | I²C serial interface pins - support standard/fast-mode timing; require pull-up resistors to VCC |
| 18 | AS | Address-select input - sets I²C slave address via voltage level (LOW/MID1/MID2/HIGH) |
| 19 | ADC | 3-bit ADC input - monitors analog voltage (0–VCC) with 0.03×VCC accuracy for diagnostics or AGC feedback |
| 20–22, 28 | BS3, BS1, BS2, BS4 | NPN band-switch driver outputs - emitter-follower configuration; each sinks 10 mA at 3.5 V for RF switch control |
| 23, 24 | IF IN1, IF IN2 | Dual IF amplifier inputs - accept filtered IF signals for gain/AGC processing within the IC |
| 25, 26 | MIX OUT1, MIX OUT2 | Mixer differential outputs - feed internal IF amplifiers; support two independent IF paths |
| 29, 30 | VHF RF IN, UHF RF IN | Separated RF inputs - allow simultaneous VHF/UHF antenna connection with band-select isolation |
Key Features
| Feature | Design Value |
|---|---|
| Three-band LO synthesis | Covers VHF-LOW (55–120 MHz), VHF-HIGH (125–220 MHz), and UHF (470–862 MHz) bands with dedicated oscillator sections |
| I²C programmable PLL | 15-bit frequency word + selectable reference dividers (512/640/1024) enable precise channel stepping and flexible crystal usage |
| Integrated 30-V VTU amplifier | Drives high-voltage varactors directly - eliminates need for external tuning amplifier in most TV tuner designs |
| Four NPN band-switch drivers | Emitter-follower outputs (BS1–BS4) with 10-mA sink capability simplify RF front-end switching without discrete transistors |
| Dual IF amplifier paths | Independent IF IN1/IN2 and MIX OUT1/MIX OUT2 support diversity reception or dual-tuner architectures |
| On-chip 3-bit ADC | Monitors analog voltage on ADC pin (0–VCC range) with 0.03×VCC accuracy - usable for signal strength indication or thermal monitoring |
Applications
| Analog Terrestrial TV Tuner | VCR/DVD Recorder Tuner |
|---|---|
|
Use Scenario: Reception of PAL/NTSC broadcast signals from rooftop or indoor antenna in legacy TV sets. IC Role / Device Role / Timing Role: Primary RF-to-IF downconverter with integrated PLL-controlled LO, band switching, and IF amplification. Use Value: Eliminates discrete oscillator, mixer, and PLL ICs - reduces BOM count and PCB area while maintaining 9.5-dB noise figure at 58 MHz. |
Use Scenario: Channel selection and signal conditioning in consumer-grade VCRs and DVD recorders with analog TV input. IC Role / Device Role / Timing Role: Full-spectrum tuner IC handling VHF/UHF band switching, IF filtering interface, and I²C-controlled channel lock. Use Value: Enables compact tuner module design with only one external 4-MHz crystal and passive IF filter - no external VCO needed. |
| Set-Top Box (STB) Tuner | Legacy Cable TV Receiver |
|
Use Scenario: Digital-to-analog conversion path in early-generation digital STBs supporting analog passthrough. IC Role / Device Role / Timing Role: Analog front-end tuner providing IF output to MPEG decoder's analog input stage. Use Value: Delivers 25-dB conversion gain and <87-dBµV cross-modulation distortion - meets EIA/CEA-600 linearity requirements. |
Use Scenario: Signal acquisition in cable-ready TVs and standalone cable receivers prior to QAM demodulation. IC Role / Device Role / Timing Role: Multi-band RF tuner with programmable reference divider supporting 6-MHz channel spacing in 54–860 MHz range. Use Value: Supports all North American cable bands (low-VHF, high-VHF, UHF) using single IC with BS1–BS4 band-switch logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TV tuner IC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SI2151-A10-GM | Single-die silicon tuner; integrates IF filter and demodulator; no external crystal required; 1.8-V core, 3.3-V I/O | Targets modern digital TV systems with QAM/8VSB demodulation; lacks analog IF output and 30-V VTU | Choose SI2151-A10-GM for digital-only STBs; SN761678DBT remains preferred for analog IF output and legacy crystal-based PLL designs. |
| TDA9886HN/C1 | IF demodulator + PLL alignment IC; requires external mixer and oscillator; no integrated RF front-end or band switches | Used in hybrid tuner architectures where RF section is discrete; no UHF/VHF switching capability onboard | Select TDA9886HN/C1 when reusing existing RF modules; SN761678DBT provides full integration including BS1–BS4 drivers and VTU amplifier. |
Compared with SI2151-A10-GM and TDA9886HN/C1, the SN761678DBT uniquely combines three-band oscillator synthesis, 30-V tuning voltage generation, and four integrated band-switch drivers in a single 30-pin TSSOP - making it irreplaceable for cost-sensitive analog TV tuner designs requiring minimal external components and crystal-based frequency control.
Availability
SN761678DBT is available at Aetrix Electronics and suitable for analog terrestrial TV sets, VCR/DVD recorders, and legacy set-top boxes requiring stable component supply and long-lifecycle support for maintenance production.
Supply support for SN761678DBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies with over 50 years of innovation in signal chain and power management ICs.
The SN761678DBT belongs to TI's legacy TV tuner product line, designed specifically for cost-effective, high-performance analog broadcast reception in consumer electronics - emphasizing integration of PLL, mixer, oscillator, and band-switch functions in one package.
FAQ
What is the function of the VTU pin on the SN761678DBT?
The VTU pin on the SN761678DBT is the 30-V tuning voltage amplifier output. It drives varactor diodes in external VHF and UHF oscillator tanks to control resonant frequency. With a low-level output voltage of 0.4–0.5 V and leakage current under 10 µA when disabled, the VTU pin enables precise analog tuning without external amplification - a key feature distinguishing the SN761678DBT from later digital tuners.
Does the SN761678DBT support I²C fast-mode operation?
Yes, the SN761678DBT supports I²C fast-mode operation at up to 400 kHz on its SCL/SDA pins. The device meets standard I²C timing requirements including data hold time (0 µs), start setup time (0.6 µs), and rise/fall times (0.3 µs), allowing rapid register writes for channel changes. This capability is confirmed in the Electrical Characteristics table of the SLES185 datasheet for SN761678DBT.
What are the supported reference divider ratios for the SN761678DBT PLL?
The SN761678DBT supports three programmable reference divider ratios: 512, 640, and 1024 - selected via RSA and RSB bits in the control byte. These ratios determine the effective reference frequency applied to the PLL phase detector (e.g., 4 MHz / 1024 = 3.90625 kHz), enabling flexible channel spacing and compatibility with standard 4-MHz crystals across global TV standards.
Can the SN761678DBT operate without an external crystal?
No, the SN761678DBT requires an external 4-MHz crystal connected to the XTAL pin. The internal oscillator circuit is designed for ac-coupled 4-MHz fundamental-mode crystals with ESR between 25 Ω and 300 Ω. There is no internal RC oscillator or clock input option - the crystal is mandatory for PLL reference generation, as specified in the SLES185 datasheet for SN761678DBT.
How many bands does the SN761678DBT support, and how is band selection controlled?
The SN761678DBT supports three RF bands: VHF-LOW, VHF-HIGH, and UHF. Band selection is controlled via four NPN band-switch drivers (BS1–BS4) using a fixed logic mapping: BS1=1/BS2=0/BS4=0 selects VHF-LOW; BS1=0/BS2=1/BS4=0 selects VHF-HIGH; BS1=0/BS2=0/BS4=1 selects UHF. BS3 is unused in standard configurations per the functional description in the SN761678DBT datasheet.
SN761678DBT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- -
- Applications:
- -
- Standards:
- -
- Control Interface:
- -
- Voltage - Supply:
- -
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SN761678DBT FAQ
1.How can I place an order for SN761678DBT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN761678DBT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN761678DBT reliable?
The price and inventory of SN761678DBT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN761678DBT is usually 5 days.
3.What payment methods are accepted for SN761678DBT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN761678DBT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN761678DBT?
SN761678DBT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN761678DBT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN761678DBT?
For technical support, including SN761678DBT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN761678DBT requirements.
6.How does Aetrix verify that SN761678DBT is sourced from the original manufacturer or authorized distributors?
All SN761678DBT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN761678DBT meets industry standards.
7.What is the process for return or replacement of SN761678DBT?
All SN761678DBT units undergo pre-shipment inspection (PSI). If there is an issue with SN761678DBT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN761678DBT part is unused and in its original packaging.
Return procedure for SN761678DBT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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