ACM1604
16-bit SAR ADC with 4 differential channels, 1 MSPS sampling rate, and SPI interface for industrial applications.
Product Overview
Description
The ACM1604 is a high-performance 16-bit successive approximation register (SAR) analog-to-digital converter featuring four differential input channels.
With a sampling rate of 1 MSPS and excellent DC accuracy (INL: +/- 1 LSB), this ADC is ideal for multi-channel sensor monitoring and industrial control systems.
The device operates from a single 5V supply and includes an internal reference, programmable gain amplifier, and robust ESD protection.
Product Series
ACM
Primary Application
Industrial sensor interfaces
Key Features
- 16-bit resolution with no missing codes
- 1 MSPS sampling rate
- 4 differential input channels
- Internal precision reference
- Programmable gain amplifier (1x, 2x, 4x, 8x)
- Single 5V supply operation
Specifications
| Resolution | 16-bit |
|---|---|
| Sampling Rate | 1 MSPS |
| Channels | 4 differential |
| INL | +/- 1 LSB |
| DNL | +/- 0.5 LSB |
| SNR | 93 dB |
| Power Supply | 5V |
| Interface | SPI |
| Temperature Range | -40C to +125C |
| Package | TSSOP-20 |
Applications
Industrial sensor interfaces
Sensor signal conditioning
Process control systems
Industrial automation and control
Data acquisition systems
Data acquisition and conversion
Test and measurement equipment
Data acquisition and conversion
FAE Expert Insights
"In my 15 years supporting precision analog designs, I've found the ACM1604 to be an excellent choice for industrial data acquisition systems. The 1 MSPS sampling rate combined with true 16-bit resolution makes it versatile for both control loops and measurement applications. I particularly appreciate the integrated PGA - it eliminates the need for external amplifiers in many sensor interface designs, reducing BOM cost and board space. The 120 dB CMRR is genuinely impressive and makes a real difference in noisy industrial environments. I've deployed this ADC in motor control systems where it reliably rejected switching noise that plagued other converters. One recommendation: pay close attention to the reference voltage layout. Use a solid ground plane and keep the reference bypass capacitor within 3mm of the REF pin. I've seen systems achieve 15.5 ENOB with proper layout, while poor layout can degrade performance to 13 bits."
Excellent balance of speed, resolution, and noise immunity for industrial applications
— Michael Chen, BeiLuo
Frequently Asked Questions
What is the maximum input voltage for the ACM1604?
The ACM1604 accepts differential input voltages up to +/- Vref. With the internal 4.096V reference, the maximum differential input is +/- 4.096V. The absolute maximum rating for analog inputs is -0.3V to AVDD + 0.3V. Exceeding these limits may cause permanent damage to the device. For applications requiring higher input voltages, use external resistor dividers or signal conditioning circuits.
For input voltages exceeding +/- 4.096V, implement external attenuation or contact our FAE team for alternative product recommendations.
How do I interface the ACM1604 with my microcontroller?
The ACM1604 uses a standard SPI interface with CS (Chip Select), SCLK (Serial Clock), DIN (Data In), and DOUT (Data Out) pins. Connect CS to a GPIO pin for device selection, SCLK to the SPI clock, DIN to MOSI, and DOUT to MISO. The interface supports SPI modes 0 and 3 with clock rates up to 20 MHz. A typical conversion sequence involves: 1) Pull CS low to select the device, 2) Send configuration byte on DIN, 3) Read 16-bit conversion result on DOUT, 4) Pull CS high to end transaction. The device also supports daisy-chain mode for multi-channel systems using a single SPI bus.
Ensure your microcontroller SPI supports mode 0 or 3. For multiple ADCs, consider using the daisy-chain feature to save GPIO pins.
What is the effective resolution at different sampling rates?
The ACM1604 maintains 16-bit resolution across all sampling rates up to 1 MSPS. However, effective resolution (ENOB) varies with sampling rate due to noise considerations. At 1 MSPS, expect approximately 14.5 ENOB. At 500 kSPS, ENOB improves to about 15.0 bits. At 100 kSPS and below, you can achieve the full 16-bit ENOB. The internal programmable averaging filter can improve ENOB at the cost of reduced sampling rate. For highest precision measurements, operate at lower sampling rates or use oversampling techniques in software.
For maximum precision, operate at 100 kSPS or below. For high-speed acquisition, 1 MSPS provides excellent performance with 14.5+ ENOB.
Can I use an external voltage reference with the ACM1604?
Yes, the ACM1604 supports both internal and external voltage references. The internal reference provides 4.096V with 10 ppm/°C drift, suitable for most applications. For higher precision, you can connect an external reference to the REF pin. The external reference voltage can range from 2.5V to 5.0V, allowing you to optimize the input range for your specific application. When using an external reference, the input range scales proportionally (input range = +/- Vref). Ensure your external reference has low noise and good temperature stability for best results. Bypass the REF pin with a 10uF capacitor close to the device.
Use internal reference for standard applications. Use external reference when specific voltage levels or higher precision is required.
What PCB layout considerations are important for the ACM1604?
Proper PCB layout is essential for achieving datasheet performance. Key considerations include: 1) Place decoupling capacitors (100nF + 10uF) as close as possible to AVDD and DVDD pins, ideally within 2mm. 2) Use separate analog and digital ground planes connected at a single point near the ADC. 3) Keep analog input traces short and away from digital signals. 4) Use differential routing for analog input pairs with matched trace lengths. 5) Provide adequate copper area for thermal management. 6) Avoid routing switching power supplies under or near the ADC. 7) Use solid ground planes to minimize noise coupling. Following these guidelines ensures optimal performance and noise immunity.
Follow the recommended layout in the datasheet. Contact our FAE team for layout review if experiencing noise issues.
How does the programmable gain amplifier (PGA) work?
The ACM1604 includes an integrated PGA with programmable gains of 1x, 2x, 4x, and 8x. The PGA amplifies small input signals before conversion, improving the effective resolution for low-level signals. For example, with a 100mV input signal and 8x gain, the ADC sees 800mV, utilizing more of the converter's dynamic range. The PGA is configured through the SPI interface by setting the appropriate bits in the configuration register. Note that higher gain settings reduce the maximum allowable input voltage range proportionally. At 8x gain, the maximum differential input is +/- 0.512V (4.096V / 8). The PGA features excellent linearity and low drift, maintaining accuracy across all gain settings.
Use PGA for small signals to maximize dynamic range. Ensure input signal times gain does not exceed reference voltage.