ADA4940-2ACPZ - Low Power Differential ADC Driver | Analog Devices
MPN: ADA4940-2ACPZ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.21 | $7.21 |
| 10 | $6.49 | $64.90 |
| 100 | $5.77 | $577.00 |
| 500 | $5.05 | $2,525.00 |
| 1,000 | $4.33 | $4,330.00 |
ADA4940-2ACPZ Overview
A fully differential amplifier (FDA) is an amplifier with differential inputs and differential outputs, used to convert single-ended signals to differential, buffer differential signals, and drive ADCs. It is a key building block in signal chains, sitting between the sensor/amplifier stage and the ADC, ensuring optimal signal integrity and common-mode rejection. The ADA4940-2 belongs to the family of differential amplifiers, which are a subset of operational amplifiers, which are part of the broader category of analog integrated circuits.
Key features include a -3 dB bandwidth of 26 MHz, a slew rate of 45 V/µs, and a low input voltage noise of 3.9 nV/√Hz. The device achieves a spurious-free dynamic range (SFDR) of -110 dBc at 100 kHz and a THD of -110 dB at 100 kHz, ensuring high fidelity for precision applications. It also features an output common-mode voltage control pin (VOCM) for level shifting, and a power-down pin for standby operation.
The ADA4940-2 is fabricated on Analog Devices' advanced dielectrically isolated SiGe bipolar process, providing excellent DC accuracy with a maximum input offset voltage of 150 µV and a typical offset drift of 0.5 µV/°C. The device is available in a Pb-free, 4 mm × 4 mm, 24-lead LFCSP package, which is compact and suitable for space-constrained designs.
Typical applications include driving PULSAR ADCs, such as the AD7985 and AD7986, in medical imaging, industrial process control, and instrumentation. The low power consumption and high performance make it suitable for battery-powered portable devices and multi-channel data acquisition systems.
When designing with the ADA4940-2, ensure proper supply decoupling with 0.1 µF capacitors close to the supply pins. The VOCM pin should be driven by a low-impedance source to set the output common-mode voltage, and the feedback network should be matched to maintain balance and minimize distortion.
Drop-in alternatives for ADA4940-2ACPZ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ADA4940-2ACPZ (same form factor and footprint) — differing in Number of Channels, Package, Supply Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADA4940-2ACPZ-R2
✅ Drop-In📋 Reference alternative (not in catalog)
ADA4940-2ACPZ-R7
✅ Drop-In📋 Reference alternative (not in catalog)
ADA4950-2YCPZ-RL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADA4930-2YCPZ-R2
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
THS4521
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADA4940-2ACPZ Maximum Ratings & Electrical Characteristics
| Number of Channels | 2 (Dual) |
| Amplifier Type | Fully Differential |
| Supply Voltage Range | 3.3 V to 7 V (single), ±1.65 V to ±3.5 V (dual) |
| Quiescent Current per Amplifier | 1.25 mA |
| Bandwidth (-3 dB) | 26 MHz |
| Slew Rate | 45 V/µs |
| Input Voltage Noise | 3.9 nV/√Hz |
| Input Offset Voltage (max) | 150 µV |
| Input Offset Drift | 0.5 µV/°C (typical) |
| SFDR | -110 dBc at 100 kHz |
| THD | -110 dB at 100 kHz |
| Output Common-Mode Range | 0.1 V to 3.4 V (single 5V supply) |
| Package | 24-Lead LFCSP (4x4 mm) |
| Operating Temperature Range | -40°C to +125°C |
| RoHS Status | Compliant |
| Mounting Type | Surface Mount |
ADA4940-2ACPZ Pin Configuration
| Pin 1 | OUT+ — Positive differential output |
| Pin 2 | OUT- — Negative differential output |
| Pin 3 | VOCM — Output common-mode voltage control |
| Pin 4 | V+ — Positive supply |
| Pin 5 | V- — Negative supply (connect to ground for single supply) |
| Pin 6 | PD — Power-down (active high) |
| Pin 7 | IN+ — Non-inverting input |
| Pin 8 | IN- — Inverting input |
| Pin 9 | VOCM — Output common-mode voltage control (second channel) |
| Pin 10 | OUT+ — Positive differential output (second channel) |
| Pin 11 | OUT- — Negative differential output (second channel) |
| Pin 12 | V+ — Positive supply (second channel) |
Typical Applications
ADA4940-2ACPZ is suitable for 6 applications: ADC Driver for PULSAR ADCs, Medical Imaging, Industrial Process Control, Instrumentation, Portable Battery-Powered Devices, Communications.
ADC Driver for PULSAR ADCs
The ADA4940-2ACPZ is specifically designed to drive low power, high resolution SAR ADCs like the AD7985 and AD7986. Its low noise (3.9 nV/√Hz) and low distortion (-110 dB THD) ensure that the ADC's performance is not degraded. The differential output provides common-mode rejection and doubles the dynamic range compared to single-ended drive. With only 1.25 mA quiescent current per amplifier, it is ideal for battery-powered and multi-channel systems where power is limited. The VOCM pin allows precise setting of the output common-mode voltage to match the ADC's input range, ensuring optimal performance.
Recommended
Medical Imaging
In medical imaging systems such as ultrasound and MRI, the ADA4940-2ACPZ provides the low noise and high linearity required for accurate signal acquisition. Its -110 dB SFDR at 100 kHz ensures that weak signals are not masked by distortion. The low power consumption (1.25 mA per channel) is critical for portable and battery-operated devices. The differential output helps reject common-mode interference from the environment, improving signal integrity. The wide temperature range (-40°C to +125°C) makes it suitable for clinical environments.
Recommended
Industrial Process Control
The ADA4940-2ACPZ is well-suited for industrial process control systems that require precise measurement of sensors and transducers. Its low offset voltage (150 µV max) and low drift (0.5 µV/°C) ensure accurate DC accuracy over temperature. The differential output provides immunity to common-mode noise, which is common in industrial environments. The device can operate from a single 5V supply, simplifying power design. Its small 4x4 mm LFCSP package saves board space in dense control systems.
Recommended
Instrumentation
In precision instrumentation such as spectrum analyzers and data loggers, the ADA4940-2ACPZ provides the high dynamic range needed to capture small signals. Its 26 MHz bandwidth supports high-speed data acquisition, while the low noise and distortion preserve signal fidelity. The dual-channel configuration allows simultaneous sampling of multiple signals, reducing component count. The power-down pin enables power saving in battery-operated instruments. The device's excellent AC performance makes it a reliable choice for laboratory equipment.
Recommended
Portable Battery-Powered Devices
The ADA4940-2ACPZ's low quiescent current (1.25 mA per amplifier) makes it ideal for portable devices where battery life is critical. It can operate from a single 3.3V supply, compatible with common battery voltages. The small LFCSP package minimizes PCB area, enabling compact designs. The device's low noise ensures high-quality signal acquisition in portable medical monitors, handheld instruments, and IoT sensors. The power-down feature further extends battery life in standby mode.
Recommended
Communications
In communications systems, the ADA4940-2ACPZ can be used to drive ADCs in base stations and software-defined radios. Its high SFDR (-110 dBc) and low distortion ensure that the signal chain does not introduce intermodulation products. The differential output is compatible with differential ADC inputs, improving common-mode rejection. The device's low power consumption is beneficial in multi-channel systems. The wide bandwidth supports IF sampling applications up to 26 MHz.
Recommended
Recommended Products Summary
Engineering reference data for ADA4940-2ACPZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADA4940-2ACPZ-R2 | ADA4940-2ACPZ-R7 | ADA4950-2YCPZ-RL | ADA4930-2YCPZ-R2 | THS4521 |
|---|---|---|---|---|---|---|
| Package | 24-Lead LFCSP (4x4 mm) | 24-Lead LFCSP (4x4 mm) | 24-Lead LFCSP (4x4 mm) | 24-Lead LFCSP (4x4 mm) | 24-Lead LFCSP (4x4 mm) | 24-Lead LFCSP (4x4 mm) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Texas Instruments |
| Number of Channels | 2 | 2 | 2 | 2 | 2 | 1 |
| Supply Current per Amplifier | 1.25 mA | 1.25 mA | 1.25 mA | 9.5 mA | 40 mA | 1.1 mA |
| Bandwidth (-3 dB) | 26 MHz | 26 MHz | 26 MHz | 500 MHz | 1.35 GHz | 145 MHz |
| Input Voltage Noise | 3.9 nV/√Hz | 3.9 nV/√Hz | 3.9 nV/√Hz | 2.2 nV/√Hz | 2.2 nV/√Hz | 4.6 nV/√Hz |
| SFDR at 100 kHz | -110 dBc | -110 dBc | -110 dBc | -95 dBc | -90 dBc | -100 dBc |
| Supply Voltage Range | 3.3V to 7V | 3.3V to 7V | 3.3V to 7V | 3.3V to 5V | 3.3V to 5V | 2.7V to 5.25V |
Key Differentiators
- Ultra-low power consumption (vs ADA4950-2YCPZ-RL)
- Lower noise (vs THS4521)
- Dual-channel integration (vs THS4521)
Design Notes
The ADA4940-2ACPZ operates from a single 3.3V to 7V supply or dual supplies. For single-supply operation, connect V- to ground and ensure the input common-mode voltage is within the specified range. Use 0.1 µF decoupling capacitors close to each supply pin to minimize noise and ensure stability.
For optimal performance, place the ADA4940-2ACPZ close to the ADC it drives to minimize trace length and parasitic capacitance. Use a solid ground plane and route differential traces symmetrically to maintain balance. The exposed pad on the LFCSP package should be soldered to the PCB ground for thermal and electrical performance.
Avoid driving purely capacitive loads directly, as the bond wire and pin inductance can cause ringing and loss of phase margin. Use a series resistor or an RC snubber if necessary. Also, ensure the VOCM pin is driven by a low-impedance source to set the output common-mode voltage accurately.
Compliance Information
RoHS compliant per Analog Devices product page. Not AEC-Q100 qualified.
