d166e5955dcc139515bbc8e652aa58e991b96540
BOM-DAT/speaker-dat/speaker-dat.md
| ... | ... | @@ -26,4 +26,23 @@ Sound Performance: |
| 26 | 26 | There is no inherent sound quality difference between 4-ohm and 8-ohm speakers. However: |
| 27 | 27 | |
| 28 | 28 | - A 4-ohm speaker may be slightly louder if the amplifier can handle it because it draws more power from the amplifier. |
| 29 | -- Matching the amplifier's power output with the speaker's impedance ensures optimal sound quality and avoids distortion or damage. |
|
| ... | ... | \ No newline at end of file |
| 0 | +- Matching the amplifier's power output with the speaker's impedance ensures optimal sound quality and avoids distortion or damage. |
|
| 1 | + |
|
| 2 | + |
|
| 3 | +## tech |
|
| 4 | + |
|
| 5 | +- [[amplifier-dat]] - [[amplifier-audio-dat]] |
|
| 6 | + |
|
| 7 | +- [[signal-dat]] - [[signal-differential-dat]] |
|
| 8 | + |
|
| 9 | +- [[I2S-dat]] |
|
| 10 | + |
|
| 11 | +- [[speaker-dat]] - [[headphone-dat]] |
|
| 12 | + |
|
| 13 | + |
|
| 14 | + |
|
| 15 | + |
|
| 16 | + |
|
| 17 | +## ref |
|
| 18 | + |
|
| 19 | + |
Board-dat/AMP/AMP1024-dat/2026-02-07-18-40-29.png
| ... | ... | Binary files /dev/null and b/Board-dat/AMP/AMP1024-dat/2026-02-07-18-40-29.png differ |
Board-dat/AMP/AMP1024-dat/AMP1024-dat.md
| ... | ... | @@ -0,0 +1,28 @@ |
| 1 | + |
|
| 2 | +# AMP1024-dat |
|
| 3 | + |
|
| 4 | +## Info |
|
| 5 | + |
|
| 6 | +product url - |
|
| 7 | + |
|
| 8 | +### Board Map, Dimension, Pins, chip info, Use Guide, Setup Jumper, etc. |
|
| 9 | + |
|
| 10 | +- [[max97220-dat]] - [[ad-audio-dat]] - [[analog-device-dat]] - [[amplifier-audio-dat]] |
|
| 11 | + |
|
| 12 | + |
|
| 13 | + |
|
| 14 | + |
|
| 15 | + |
|
| 16 | + |
|
| 17 | + |
|
| 18 | +## Applications, category, tags, etc. |
|
| 19 | + |
|
| 20 | +## Demo Code and Video |
|
| 21 | + |
|
| 22 | +## ref |
|
| 23 | + |
|
| 24 | +- [[]] |
|
| 25 | + |
|
| 26 | +- legacy wiki page |
|
| 27 | + |
|
| 28 | + |
Board-dat/NBL/NBL1055-dat/NBL1055-dat.md
| ... | ... | @@ -3,6 +3,8 @@ |
| 3 | 3 | |
| 4 | 4 | - [[NBL1050-dat]] - [[NBL1051-dat]] - [[NBL1054-dat]] - [[NBL1055-dat]] |
| 5 | 5 | |
| 6 | +- [[qualcomm-dat]] |
|
| 7 | + |
|
| 6 | 8 | ## Info |
| 7 | 9 | |
| 8 | 10 | [product url - EB8635 EB8645 Bluetooth BT4.0 Audio Board [Type]](https://www.electrodragon.com/product/exbt-ex8635-ex8645-bluetooth-bt4-0-audio-board/?attribute_pa_attributes=ex8645-breakout-board) |
Chip-dat/Analog-device-dat/AD-audio-dat/AD-audio-dat.md
| ... | ... | @@ -0,0 +1,53 @@ |
| 1 | +# AD-audio-dat |
|
| 2 | + |
|
| 3 | + |
|
| 4 | +## MAX97220 |
|
| 5 | + |
|
| 6 | +The MAX97220 is a high-fidelity DirectDrive® headphone amplifier and differential line driver from Analog Devices, designed for portable audio applications. It removes the need for large output coupling capacitors by using an on-chip charge pump to create a negative rail, allowing the outputs to be biased around ground. |
|
| 7 | + |
|
| 8 | +Quick summary |
|
| 9 | + |
|
| 10 | +- Input voltage: 2.5 V – 5.5 V |
|
| 11 | +- Typical power consumption: ≈12.65 mW |
|
| 12 | +- Output: DirectDrive (no large output caps required) |
|
| 13 | +- Commonly used with DACs (example: CX31993) in USB-C to 3.5 mm DAC/amp dongles |
|
| 14 | + |
|
| 15 | +Key specifications |
|
| 16 | + |
|
| 17 | +| Parameter | Value | |
|
| 18 | +|---|---:| |
|
| 19 | +| Supply voltage | 2.5 V – 5.5 V | |
|
| 20 | +| Typical power | ≈ 12.65 mW | |
|
| 21 | +| Headphone output (typ.) | 125 mW into 32 Ω (VCC = 5 V) | |
|
| 22 | +| Line output | 3 V RMS into 1 kΩ (VCC = 5 V) | |
|
| 23 | +| High-impedance output | 2 V RMS into 600 Ω (VCC = 3.3 V) | |
|
| 24 | +| Supported headphone impedance | Up to ~300 Ω (depends on required SPL) | |
|
| 25 | +| THD+N | Low (typical values depend on operating point) | |
|
| 26 | +| Turn-on time | A/C/E versions: ~5.5 ms; B/D versions: ~130 ms | |
|
| 27 | +| Package | 16-pin TQFN (3 mm × 3 mm) | |
|
| 28 | + |
|
| 29 | +Features |
|
| 30 | + |
|
| 31 | +- DirectDrive® architecture (on-chip negative rail via charge pump) |
|
| 32 | +- Eliminates large distortion-inducing output coupling capacitors |
|
| 33 | +- Low noise and low THD+N |
|
| 34 | +- Click-and-pop suppression circuitry |
|
| 35 | +- Power-down (shutdown) modes for low-power applications |
|
| 36 | + |
|
| 37 | +Typical applications |
|
| 38 | + |
|
| 39 | +- USB-C to 3.5 mm DAC/amp dongles (paired with DACs such as CX31993) |
|
| 40 | +- Portable audio players and mobile devices |
|
| 41 | +- Set-top boxes and TV audio (slower turn-on variants) |
|
| 42 | +- High-impedance headphone driving and balanced line outputs |
|
| 43 | + |
|
| 44 | +Variants and notes |
|
| 45 | + |
|
| 46 | +- Fast turn-on versions (A/C/E) are optimized for headphone use (~5.5 ms). Slower turn-on versions (B/D) are intended for applications like set-top boxes where longer startup is acceptable (~130 ms). |
|
| 47 | +- The raw outputs are DirectDrive and may still require output filtering or buffers depending on system load and EMI requirements. |
|
| 48 | + |
|
| 49 | + |
|
| 50 | + |
|
| 51 | +## ref |
|
| 52 | + |
|
| 53 | +- [[analog-device-dat]] - [[AD-audio-dat]] |
|
| ... | ... | \ No newline at end of file |
Chip-dat/TI-dat/TI-dat.md
| ... | ... | @@ -39,7 +39,7 @@ TPDxEUSB30 2-, 4-Channel ESD Protection for Super-Speed USB 3.0 Interface |
| 39 | 39 | |
| 40 | 40 | - [[voltage-reference-dat]] |
| 41 | 41 | |
| 42 | -- [[differential-signal-dat]] |
|
| 42 | +- [[signal-differential-dat]] |
|
| 43 | 43 | |
| 44 | 44 | |
| 45 | 45 | ## ref |
Chip-dat/qualcomm-dat/qualcomm-dat.md
| ... | ... | @@ -9,11 +9,24 @@ |
| 9 | 9 | |
| 10 | 10 | - CSR8645, CSR8635, CSR8625, CSR8615, CSR8605, CSR8640, CSR8630, CSR8620, CSR8610, CSR8600 |
| 11 | 11 | |
| 12 | -- [[qualcomm-dat]] - [[BT-audio-dat]] - [[CSRA64215-dat]] |
|
| 12 | +- [[qualcomm-dat]] - [[BT-audio-dat]] |
|
| 13 | 13 | |
| 14 | 14 | |
| 15 | 15 | - [[CSR8635-dat]] - [[CSR-dat]] |
| 16 | 16 | |
| 17 | + |
|
| 18 | + |
|
| 19 | +- [[bt-audio-dat]] |
|
| 20 | + |
|
| 21 | +- [[CSR8645-dat]] - [[CSR8635-dat]] |
|
| 22 | + |
|
| 23 | + |
|
| 24 | + |
|
| 25 | +## board |
|
| 26 | + |
|
| 27 | +- [[NBL1055-dat]] |
|
| 28 | + |
|
| 29 | + |
|
| 17 | 30 | ## ref |
| 18 | 31 | |
| 19 | 32 | - [[bt-audio-dat]] |
| ... | ... | \ No newline at end of file |
Circuits-dat/circuits-dat.md
| ... | ... | @@ -9,7 +9,7 @@ |
| 9 | 9 | |
| 10 | 10 | - [[protection-dat]] |
| 11 | 11 | |
| 12 | -- [[differential-signal-dat]] - [[signal-dat]] |
|
| 12 | +- [[signal-differential-dat]] - [[signal-dat]] |
|
| 13 | 13 | |
| 14 | 14 | - [[MMA7660-dat]] - [[SD-card-dat]] |
| 15 | 15 |
Network-dat/Bluetooth-dat/bt-audio-dat/bt-audio-dat.md
| ... | ... | @@ -5,6 +5,13 @@ |
| 5 | 5 | |
| 6 | 6 | [legacy wiki page](https://www.electrodragon.com/w/Category:BT_Audio) |
| 7 | 7 | |
| 8 | +## tech |
|
| 9 | + |
|
| 10 | +- [[bluetooth-dat]] |
|
| 11 | + |
|
| 12 | +- [[amplifier-audio-dat]] |
|
| 13 | + |
|
| 14 | + |
|
| 8 | 15 | ## boards |
| 9 | 16 | |
| 10 | 17 | - [[NBL1037-dat]] - [[NBL1038-dat]] - [[NBL1097-dat]] |
PCB-dat/PCB-design-dat/PCB-trace-dat.md
| ... | ... | @@ -1,7 +1,7 @@ |
| 1 | 1 | |
| 2 | 2 | # PCB-trace-dat |
| 3 | 3 | |
| 4 | -- [[differential-signal-dat]] |
|
| 4 | +- [[signal-differential-dat]] |
|
| 5 | 5 | |
| 6 | 6 | ### Quick reference table (External trace, 1 oz copper, ΔT = 10°C): |
| 7 | 7 |
SDK-dat/PIC-PROG/PICKIT-DAT.md
| ... | ... | @@ -1,8 +1,19 @@ |
| 1 | 1 | |
| 2 | 2 | |
| 3 | + |
|
| 4 | +# pickit-dat |
|
| 5 | + |
|
| 6 | + |
|
| 3 | 7 | - MCLR |
| 4 | 8 | - VCC |
| 5 | 9 | - GND |
| 6 | 10 | - PGD |
| 7 | 11 | - PGC |
| 8 | 12 | |
| 13 | + |
|
| 14 | +## ref |
|
| 15 | + |
|
| 16 | +- [[pic-sdk-dat]] |
|
| 17 | + |
|
| 18 | + |
|
| 19 | + |
SDK-dat/PIC-SDK-dat/pic-sdk-dat.md
| ... | ... | @@ -5,6 +5,8 @@ |
| 5 | 5 | - legacy wiki page - https://w.electrodragon.com/w/PIC_SDK |
| 6 | 6 | |
| 7 | 7 | |
| 8 | +- [[pickit-dat]] |
|
| 9 | + |
|
| 8 | 10 | ## Boards |
| 9 | 11 | |
| 10 | 12 | - [[DOD1049-dat]] |
| ... | ... | @@ -35,6 +37,10 @@ |
| 35 | 37 | |
| 36 | 38 |  |
| 37 | 39 | |
| 40 | + |
|
| 41 | + |
|
| 42 | + |
|
| 43 | + |
|
| 38 | 44 | ### Programming PIC16F72 |
| 39 | 45 | |
| 40 | 46 | - power option: |
SDK-dat/avr-sdk-dat/UPDI-dat/UPDI-dat.md
| ... | ... | @@ -5,6 +5,11 @@ |
| 5 | 5 | Wiring: 3.3V or 5V, GND, UPDI |
| 6 | 6 | |
| 7 | 7 | |
| 8 | +## supported board |
|
| 9 | + |
|
| 10 | +- [[ILE1073-dat]] - [[DAR1064-dat]] |
|
| 11 | + |
|
| 12 | + |
|
| 8 | 13 | ## programmers |
| 9 | 14 | |
| 10 | 15 | ## atmel ICE |
Tech-dat/amplifier-dat/amplifier-audio-dat/amplifier-audio-dat.md
| ... | ... | @@ -1,7 +1,35 @@ |
| 1 | -# Audio-amplifier-dat |
|
| 1 | +# amplifier-audio-dat |
|
| 2 | + |
|
| 3 | + |
|
| 4 | + |
|
| 5 | + |
|
| 6 | +## tech |
|
| 7 | + |
|
| 8 | +- [[amplifier-dat]] - [[amplifier-audio-dat]] |
|
| 9 | + |
|
| 10 | +- [[signal-dat]] - [[signal-differential-dat]] |
|
| 11 | + |
|
| 12 | +- [[I2S-dat]] |
|
| 13 | + |
|
| 14 | +- [[speaker-dat]] - [[headphone-dat]] |
|
| 15 | + |
|
| 16 | + |
|
| 17 | +## boards |
|
| 18 | + |
|
| 19 | +- [[AMP1024-dat]] |
|
| 20 | + |
|
| 21 | + |
|
| 22 | + |
|
| 23 | +## chip |
|
| 24 | + |
|
| 2 | 25 | |
| 3 | 26 | - [[ST-audio-amp-dat]] - [[ST-dat]] |
| 4 | 27 | |
| 28 | +- [[analog-device-dat]] - [[AD-audio-dat]] |
|
| 29 | + |
|
| 30 | +- [[diodes-dat]] - [[PAM-dat]] |
|
| 31 | + |
|
| 32 | +- [[TI-AMP-dat]] |
|
| 5 | 33 | |
| 6 | 34 | - [[OPA1622-dat]] == SoundPlus™ Audio Operational Amplifier with High Performance, Low THD+N and Bipolar Input |
| 7 | 35 | |
| ... | ... | @@ -13,7 +41,7 @@ Low-Power Audio Amplifiers |
| 13 | 41 | |
| 14 | 42 | |
| 15 | 43 | |
| 16 | -- [[diodes-dat]] - [[PAM-dat]] |
|
| 44 | + |
|
| 17 | 45 | |
| 18 | 46 | - [[heroic-dat]] |
| 19 | 47 | |
| ... | ... | @@ -37,6 +65,11 @@ Low-Power Audio Amplifiers |
| 37 | 65 | |
| 38 | 66 | - [[HT6872-dat]] |
| 39 | 67 | |
| 68 | + |
|
| 69 | + |
|
| 70 | + |
|
| 71 | + |
|
| 72 | + |
|
| 40 | 73 | ## more chip |
| 41 | 74 | |
| 42 | 75 | OPA1678 IDR SOIC-8 Dual Audio Operational Amplifier IC Chip |
Tech-dat/signal-dat/differential-signal-dat/differential-signal-dat.md
| ... | ... | @@ -1,105 +0,0 @@ |
| 1 | - |
|
| 2 | -# differential-signal-dat |
|
| 3 | - |
|
| 4 | -## board |
|
| 5 | - |
|
| 6 | -- [[DPR1097-dat]] |
|
| 7 | - |
|
| 8 | - |
|
| 9 | -## 🔍 Key Differences: RS-485 vs RS-422 |
|
| 10 | - |
|
| 11 | -| Feature | RS-485 | RS-422 | |
|
| 12 | -|------------------|------------------------|----------------------------| |
|
| 13 | -| Driver count | Multiple drivers | One driver only | |
|
| 14 | -| Receiver count | Up to 32 receivers | Typically up to 10 | |
|
| 15 | -| Duplex mode | Half or full duplex | Full duplex (typical) | |
|
| 16 | -| Biasing required | ✅ Yes (often) | ❌ Not usually needed | |
|
| 17 | -| Termination | ✅ Yes (120Ω) | ✅ Yes (120Ω) | |
|
| 18 | - |
|
| 19 | ---- |
|
| 20 | - |
|
| 21 | -### 🧠 MAX490 in RS-422 Setup |
|
| 22 | - |
|
| 23 | -- The **MAX490 can act as the driver or receiver** in an RS-422 setup. |
|
| 24 | -- Ensure only **one driver is active** on the bus. |
|
| 25 | -- Communication is **half-duplex only**, due to MAX490 design. |
|
| 26 | -- For full-duplex RS-422, use a different transceiver (e.g., MAX491). |
|
| 27 | - |
|
| 28 | -## MAX490 for RS422 |
|
| 29 | - |
|
| 30 | - |
|
| 31 | -| Feature | RS-422 (with MAX490) | Notes | |
|
| 32 | -|----------------------------|----------------------------------|--------------------------------------| |
|
| 33 | -| Driver | 1 (only one MAX490 TX active) | Matches RS-422 spec | |
|
| 34 | -| Receiver | Up to 32 (MAX490 supports 32 RX) | RS-422 typically supports 10 | |
|
| 35 | -| Termination needed | ✅ Yes | 120 Ω between A and B | |
|
| 36 | -| Biasing resistors needed | ❌ Usually not | Optional; only if line floats | |
|
| 37 | -| Duplex Mode | **Half-duplex only** | MAX490 can't do full-duplex RS-422 | |
|
| 38 | - |
|
| 39 | -#### ✅ Termination Resistor: |
|
| 40 | -- Use a **120 Ω** resistor between A and B at the **end of the cable**. |
|
| 41 | - |
|
| 42 | -#### ❌ Biasing Resistors: |
|
| 43 | -- **Not required** in RS-422 because the single driver maintains a known state. |
|
| 44 | -- Optional if you observe floating voltages or noise. |
|
| 45 | - |
|
| 46 | - |
|
| 47 | - |
|
| 48 | -## Pull-up and Pull-down Resistors for MAX490 (RS-485) |
|
| 49 | - |
|
| 50 | -The **MAX490** is a differential RS-485/RS-422 transceiver. While it does not require internal pull-up or pull-down resistors, **external resistors are typically used for bus biasing** to ensure known voltage levels when no device is actively driving the bus. |
|
| 51 | - |
|
| 52 | -### ✅ When Are They Needed? |
|
| 53 | - |
|
| 54 | -- When no device is guaranteed to drive the RS-485 bus (e.g., during idle periods). |
|
| 55 | -- To avoid undefined logic levels on the differential lines A and B. |
|
| 56 | -- Especially important in **multi-drop** configurations. |
|
| 57 | - |
|
| 58 | ---- |
|
| 59 | - |
|
| 60 | -### 🛠️ Recommended Biasing Setup |
|
| 61 | - |
|
| 62 | -Typical resistor values: |
|
| 63 | - |
|
| 64 | -- **Pull-up on A**: 680 Ω to +5V |
|
| 65 | -- **Pull-down on B**: 680 Ω to GND |
|
| 66 | -- **Termination resistor**: 120 Ω between A and B (at both ends of the bus) |
|
| 67 | - |
|
| 68 | ---- |
|
| 69 | - |
|
| 70 | -### 📘 Circuit Diagram |
|
| 71 | - |
|
| 72 | - +5V |
|
| 73 | - | |
|
| 74 | - R1 = 680Ω |
|
| 75 | - | |
|
| 76 | - A -----------+------------------------------+--- RS-485 Bus |
|
| 77 | - | | |
|
| 78 | - Rterm = 120Ω Other devices |
|
| 79 | - | | |
|
| 80 | - B -----------+------------------------------+--- RS-485 Bus |
|
| 81 | - | |
|
| 82 | - R2 = 680Ω |
|
| 83 | - | |
|
| 84 | - GND |
|
| 85 | - |
|
| 86 | -### 🔍 Notes |
|
| 87 | - |
|
| 88 | -- MAX490 includes **receiver failsafe** features, but **external biasing is still standard practice**. |
|
| 89 | -- In **point-to-point** setups, biasing might be optional but is still recommended for stability. |
|
| 90 | -- In **multi-drop** (multi-device) RS-485 networks, biasing is essential for reliable communication. |
|
| 91 | - |
|
| 92 | - |
|
| 93 | - |
|
| 94 | -## differential line driver |
|
| 95 | - |
|
| 96 | -- [[TI-dat]] |
|
| 97 | - |
|
| 98 | -DS26LS31MJ/883 - Quad High Speed Differential Line Driver |
|
| 99 | - |
|
| 100 | -The DS26LS31MQML is a quad differential line driver designed for digital data transmission over balanced lines. The DS26LS31MQML meets all the requirements of EIA Standard RS-422 and Federal Standard 1020. It is designed to provide unipolar differential drive to twisted-pair or parallel-wire transmission lines. |
|
| 101 | - |
|
| 102 | - |
|
| 103 | -AM26C32ID - Quadruple Differential Line Receiver |
|
| 104 | - |
|
| 105 | -AM26LS31 Quadruple Differential Line Driver |
|
| ... | ... | \ No newline at end of file |
Tech-dat/signal-dat/signal-dat.md
| ... | ... | @@ -4,7 +4,7 @@ |
| 4 | 4 | - [[digital-dat]] - [[analog-dat]] |
| 5 | 5 | |
| 6 | 6 | |
| 7 | -- [[differential-signal-dat]] |
|
| 7 | +- [[signal-differential-dat]] |
|
| 8 | 8 | |
| 9 | 9 | |
| 10 | 10 | - [[digitizer-dat]] |
Tech-dat/signal-dat/signal-differential-dat/signal-differential-dat.md
| ... | ... | @@ -0,0 +1,105 @@ |
| 1 | + |
|
| 2 | +# signal-differential-dat |
|
| 3 | + |
|
| 4 | +## board |
|
| 5 | + |
|
| 6 | +- [[DPR1097-dat]] |
|
| 7 | + |
|
| 8 | + |
|
| 9 | +## 🔍 Key Differences: RS-485 vs RS-422 |
|
| 10 | + |
|
| 11 | +| Feature | RS-485 | RS-422 | |
|
| 12 | +|------------------|------------------------|----------------------------| |
|
| 13 | +| Driver count | Multiple drivers | One driver only | |
|
| 14 | +| Receiver count | Up to 32 receivers | Typically up to 10 | |
|
| 15 | +| Duplex mode | Half or full duplex | Full duplex (typical) | |
|
| 16 | +| Biasing required | ✅ Yes (often) | ❌ Not usually needed | |
|
| 17 | +| Termination | ✅ Yes (120Ω) | ✅ Yes (120Ω) | |
|
| 18 | + |
|
| 19 | +--- |
|
| 20 | + |
|
| 21 | +### 🧠 MAX490 in RS-422 Setup |
|
| 22 | + |
|
| 23 | +- The **MAX490 can act as the driver or receiver** in an RS-422 setup. |
|
| 24 | +- Ensure only **one driver is active** on the bus. |
|
| 25 | +- Communication is **half-duplex only**, due to MAX490 design. |
|
| 26 | +- For full-duplex RS-422, use a different transceiver (e.g., MAX491). |
|
| 27 | + |
|
| 28 | +## MAX490 for RS422 |
|
| 29 | + |
|
| 30 | + |
|
| 31 | +| Feature | RS-422 (with MAX490) | Notes | |
|
| 32 | +|----------------------------|----------------------------------|--------------------------------------| |
|
| 33 | +| Driver | 1 (only one MAX490 TX active) | Matches RS-422 spec | |
|
| 34 | +| Receiver | Up to 32 (MAX490 supports 32 RX) | RS-422 typically supports 10 | |
|
| 35 | +| Termination needed | ✅ Yes | 120 Ω between A and B | |
|
| 36 | +| Biasing resistors needed | ❌ Usually not | Optional; only if line floats | |
|
| 37 | +| Duplex Mode | **Half-duplex only** | MAX490 can't do full-duplex RS-422 | |
|
| 38 | + |
|
| 39 | +#### ✅ Termination Resistor: |
|
| 40 | +- Use a **120 Ω** resistor between A and B at the **end of the cable**. |
|
| 41 | + |
|
| 42 | +#### ❌ Biasing Resistors: |
|
| 43 | +- **Not required** in RS-422 because the single driver maintains a known state. |
|
| 44 | +- Optional if you observe floating voltages or noise. |
|
| 45 | + |
|
| 46 | + |
|
| 47 | + |
|
| 48 | +## Pull-up and Pull-down Resistors for MAX490 (RS-485) |
|
| 49 | + |
|
| 50 | +The **MAX490** is a differential RS-485/RS-422 transceiver. While it does not require internal pull-up or pull-down resistors, **external resistors are typically used for bus biasing** to ensure known voltage levels when no device is actively driving the bus. |
|
| 51 | + |
|
| 52 | +### ✅ When Are They Needed? |
|
| 53 | + |
|
| 54 | +- When no device is guaranteed to drive the RS-485 bus (e.g., during idle periods). |
|
| 55 | +- To avoid undefined logic levels on the differential lines A and B. |
|
| 56 | +- Especially important in **multi-drop** configurations. |
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| 57 | + |
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| 58 | +--- |
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| 59 | + |
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| 60 | +### 🛠️ Recommended Biasing Setup |
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| 61 | + |
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| 62 | +Typical resistor values: |
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| 63 | + |
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| 64 | +- **Pull-up on A**: 680 Ω to +5V |
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| 65 | +- **Pull-down on B**: 680 Ω to GND |
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| 66 | +- **Termination resistor**: 120 Ω between A and B (at both ends of the bus) |
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| 67 | + |
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| 68 | +--- |
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| 69 | + |
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| 70 | +### 📘 Circuit Diagram |
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| 71 | + |
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| 72 | + +5V |
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| 73 | + | |
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| 74 | + R1 = 680Ω |
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| 75 | + | |
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| 76 | + A -----------+------------------------------+--- RS-485 Bus |
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| 77 | + | | |
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| 78 | + Rterm = 120Ω Other devices |
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| 79 | + | | |
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| 80 | + B -----------+------------------------------+--- RS-485 Bus |
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| 81 | + | |
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| 82 | + R2 = 680Ω |
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| 83 | + | |
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| 84 | + GND |
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| 85 | + |
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| 86 | +### 🔍 Notes |
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| 87 | + |
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| 88 | +- MAX490 includes **receiver failsafe** features, but **external biasing is still standard practice**. |
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| 89 | +- In **point-to-point** setups, biasing might be optional but is still recommended for stability. |
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| 90 | +- In **multi-drop** (multi-device) RS-485 networks, biasing is essential for reliable communication. |
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| 91 | + |
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| 92 | + |
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| 93 | + |
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| 94 | +## differential line driver |
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| 95 | + |
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| 96 | +- [[TI-dat]] |
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| 97 | + |
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| 98 | +DS26LS31MJ/883 - Quad High Speed Differential Line Driver |
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| 99 | + |
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| 100 | +The DS26LS31MQML is a quad differential line driver designed for digital data transmission over balanced lines. The DS26LS31MQML meets all the requirements of EIA Standard RS-422 and Federal Standard 1020. It is designed to provide unipolar differential drive to twisted-pair or parallel-wire transmission lines. |
|
| 101 | + |
|
| 102 | + |
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| 103 | +AM26C32ID - Quadruple Differential Line Receiver |
|
| 104 | + |
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| 105 | +AM26LS31 Quadruple Differential Line Driver |
|
| ... | ... | \ No newline at end of file |
Tech-dat/tech-dat.md
| ... | ... | @@ -94,7 +94,7 @@ |
| 94 | 94 | |
| 95 | 95 | - [[ethernet-dat]] - [[USB-dat]] |
| 96 | 96 | |
| 97 | -- [[bluetooth-dat]] - [[ble-dat]] |
|
| 97 | +- [[bluetooth-dat]] - [[ble-dat]] - [[bt-audio-dat]] |
|
| 98 | 98 | |
| 99 | 99 | - [[WIFI-DAT]] - [[mqtt-dat]] - [[TCPIP-dat]] |
| 100 | 100 |