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Analog Devices Inc./Maxim Integrated MAX9638AVB+
- Part No.:
- MAX9638AVB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 10-UFQFN
- Datasheet:
-
MAX9638AVB+.pdf
- Description:
- 3V/5V LOW-POWER, LOW-NOISE, CMOS
- Quantity:
- Payment:
- Shipping:
Inventory:3,400
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Product details
Overview
MAX9638AVB+ from Maxim Integrated is a dual, rail-to-rail input/output CMOS operational amplifier optimized for ultra-low-power, high-impedance sensor interfacing. It delivers 1.5MHz gain bandwidth at 36μA quiescent current per amplifier, 0.1pA typical input bias current, and operates from 2.1V to 5.5V over –40°C to +125°C - enabling precision transimpedance amplification in portable medical instruments and smoke detectors.
For engineers reviewing the MAX9638AVB+ datasheet, MAX9638AVB+ pinout, MAX9638AVB+ application, or MAX9638AVB+ equivalent, key selection criteria include its guaranteed ±800pA input bias current over full temperature range, 10-pin UTQFN package with dual independent shutdown controls (SHDNA/SHDNB), low 0.9fA/√Hz input current noise density, and compatibility with photodiode and piezoelectric sensor front ends requiring minimal loading.
Technical Context
The MAX9638AVB+ integrates two independent CMOS op amps in a single 10-pin UTQFN package, each featuring parallel n-channel/p-channel input stages enabling rail-to-rail common-mode input range (VSS – 0.1V to VDD + 0.1V) and rail-to-rail output swing within 100mV of rails at 3mA load. Its BiCMOS process ensures ultra-low input bias current stability across temperature.
Each amplifier supports independent active-low shutdown (SHDNA/SHDNB), reducing supply current to 1μA while placing outputs in high-impedance state. Input voltage noise is 38nV/√Hz at 1kHz, and input capacitance is 2pF - critical for stable transimpedance configurations with photodiodes up to 300pF capacitive load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Bandwidth Product | 1.5MHz - enables stable unity-gain buffering and closed-loop gains up to ~100 with phase margin >45° into 10kΩ//100pF loads. |
| Input Bias Current (max, –40°C to +125°C) | ±800pA - ensures <1µV error from 10GΩ source impedance, critical for photodiode current-to-voltage conversion. |
| Quiescent Current per Amplifier | 36µA typical - supports >1-year battery life in coin-cell–powered smoke detectors operating at 10s–minute sampling intervals. |
| Shutdown Supply Current | 1µA - reduces system standby power by >97% versus active mode, enabling duty-cycled sensor acquisition. |
| Input Voltage Noise Density | 38nV/√Hz at 1kHz - limits total integrated noise to <1.2µV RMS in 10kHz bandwidth, preserving SNR for µV-level piezoelectric signals. |
| Rail-to-Rail I/O | VIN: VSS – 0.1V to VDD + 0.1V; VOUT: within 100mV of rails at 3mA - maximizes dynamic range in single-supply 3.3V systems. |
| Operating Temperature Range | –40°C to +125°C - qualified for under-hood automotive and industrial environments without derating. |
Pinout & Package
MAX9638AVB+ is housed in a 10-pin, 2.1mm × 1.6mm UTQFN package with exposed thermal pad (V101A1CN+1 land pattern). Pin 1 is top-left corner (marking dot adjacent), pin count increases clockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | SHDN | Active-low global shutdown control (not used in MAX9638; reserved for family compatibility). |
| 2 | VDD | Positive supply input - requires 0.1µF ceramic bypass capacitor to VSS for PSRR >69dB. |
| 3 | INA− | Inverting input of amplifier A - high-impedance node; guard ring recommended for leakage control. |
| 4 | INA+ | Noninverting input of amplifier A - accepts common-mode voltages beyond rails (VSS – 0.1V to VDD + 0.1V). |
| 5 | OUTA | Output of amplifier A - rail-to-rail capable; drives 10kΩ loads with <0.03V drop at VDD = 3.3V. |
| 6 | SHDNA | Active-low shutdown control for amplifier A - pulls output to high-Z when ≤0.5V; VIH ≥1.4V. |
| 7 | SHDNB | Active-low shutdown control for amplifier B - independent of SHDNA, enabling asymmetric power gating. |
| 8 | OUTB | Output of amplifier B - electrically isolated from OUTA; supports dual-sensor simultaneous readout. |
| 9 | INB− | Inverting input of amplifier B - matched to INA− for common-mode rejection in differential sensing. |
| 10 | INB+ | Noninverting input of amplifier B - identical input structure to INA+, ensuring channel-to-channel matching. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low input bias current | 0.1pA typical (±800pA max over –40°C to +125°C) - minimizes offset drift and dark-current error in photodiode transimpedance amplifiers. |
| Dual independent shutdown | SHDNA/SHDNB pins enable per-amplifier power gating - allows one channel to remain active during calibration while the other sleeps. |
| High capacitive-load tolerance | Stable with up to 300pF in unity gain - eliminates need for external isolation resistors in most photodiode PCB layouts. |
| Rail-to-rail input stage | Common-mode range extends 100mV beyond supplies - supports direct interface to sensors referenced to VSS or VDD without level-shifting. |
| Low input current noise | 0.9fA/√Hz - dominates noise floor only above 10MHz; preserves signal integrity for high-Z piezoelectric sources below 100kHz. |
Applications
| Piezoelectric Transducer Amplifier | Photodiode Transimpedance Amplifier |
|---|---|
Use Scenario: Signal conditioning for vibration sensing in predictive maintenance modules using ceramic piezoelectric elements. IC Role / Device Role / Timing Role: Noninverting buffer with gain = 1, providing high-input-impedance interface and low-noise amplification before ADC sampling. Use Value: 0.1pA input bias current prevents signal attenuation from 100MΩ+ sensor impedance; 38nV/√Hz voltage noise maintains >80dB SNR at 1kHz. |
Use Scenario: Pulse oximetry front end where photodiode current (nA range) must be converted to voltage with minimal dark-current error. IC Role / Device Role / Timing Role: Transimpedance amplifier with 10MΩ feedback resistor, configured for DC-coupled, low-drift optical measurement. Use Value: ±800pA max input bias current over –40°C to +125°C ensures <10nA dark-current-induced offset, enabling accurate SpO₂ calculation. |
| Portable Smoke Detector Sensor Interface | Battery-Powered Medical Instrument Front End |
Use Scenario: Ionization chamber current detection in UL-certified residential smoke alarms powered by 9V alkaline batteries. IC Role / Device Role / Timing Role: Low-power current-to-voltage converter with shutdown gating synchronized to periodic chamber bias cycles. Use Value: 1µA shutdown current extends 9V battery life to >5 years; 1.5MHz GBW supports fast transient response to smoke-induced current spikes. |
Use Scenario: ECG electrode amplifier in handheld cardiac monitors requiring clinical-grade DC accuracy and low power. IC Role / Device Role / Timing Role: First-stage instrumentation amplifier input buffer, rejecting common-mode interference while preserving microvolt-level ST-segment signals. Use Value: 72dB min CMRR over full temperature range suppresses 50/60Hz mains coupling; rail-to-rail I/O maximizes ADC utilization in 3.3V systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual low-power precision op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA2333PDR | Higher 17µV max VOS, 0.02µV/°C TCVOS; no shutdown; 8-pin SOIC package (larger footprint). | Lacks independent shutdown; unsuitable for duty-cycled multi-sensor systems requiring per-channel power control. | Select when ultra-low offset drift is prioritized over shutdown flexibility and board space. |
| MCP6V82-E/MS | Zero-drift architecture; 25µV max VOS, 0.012µV/°C TCVOS; 1.2MHz GBW; 65µA IQ; no shutdown. | Superior DC precision but higher power and no shutdown - incompatible with aggressive battery-life targets. | Choose for DC-critical applications like precision weigh scales where long-term offset stability outweighs power savings. |
Compared with OPA2333PDR and MCP6V82-E/MS, MAX9638AVB+ uniquely balances ultra-low input bias current, dual independent shutdown, and 10-pin UTQFN compactness - making it optimal for space-constrained, multi-sensor battery-powered devices requiring both precision and aggressive power management.
Availability
MAX9638AVB+ is available at Aetrix Electronics and suitable for portable medical instruments, smoke detectors, and piezoelectric transducer amplifiers requiring stable component supply across automotive (-40°C to +125°C) and industrial temperature grades.
Supply support for MAX9638AVB+ 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
Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for demanding industrial, medical, and automotive applications, with expertise in low-power, high-accuracy signal conditioning.
The MAX9636/MAX9637/MAX9638 product line was engineered specifically for battery-powered sensor front ends - emphasizing ultra-low input bias current, rail-to-rail operation, and shutdown efficiency to extend runtime in portable safety and health monitoring systems.
FAQ
What is the maximum capacitive load the MAX9638AVB+ can drive stably in unity-gain configuration?
The MAX9638AVB+ is specified to drive up to 300pF of pure capacitive load stably in unity-gain configuration without external compensation. This capability is validated across –40°C to +125°C and supports direct connection to photodiode packages and long PCB traces without added series resistance. For loads exceeding 300pF or including resistive components, stability can be enhanced using RISO (5Ω–30Ω) in series with the output or RP in parallel with CL, as detailed in the MAX9638AVB+ datasheet Figure 1 and Figure 2.
Does the MAX9638AVB+ support true rail-to-rail input and output operation?
Yes, the MAX9638AVB+ supports true rail-to-rail input and output operation. Its input common-mode range extends from VSS – 0.1V to VDD + 0.1V, and its output swings within 100mV of both rails under 3mA load. This is achieved via complementary n-channel and p-channel input stages and a Class AB output stage. The specification is guaranteed over the full –40°C to +125°C temperature range and across the 2.1V to 5.5V supply range, enabling full utilization of ADC input ranges in single-supply systems.
How does the shutdown functionality work on the MAX9638AVB+?
The MAX9638AVB+ features two independent active-low shutdown inputs: SHDNA (pin 6) for amplifier A and SHDNB (pin 7) for amplifier B. When either pin is pulled ≤0.5V (VIL), the corresponding amplifier enters shutdown mode, reducing its quiescent current to 1µA and placing its output in a high-impedance state. Outputs remain isolated; pulling SHDNA low does not affect amplifier B. This allows asymmetric power management - e.g., keeping one channel active for reference while shutting down the other during idle periods.
What is the guaranteed input bias current specification for MAX9638AVB+ over temperature?
The MAX9638AVB+ guarantees an input bias current of ±800pA maximum over the full operating temperature range of –40°C to +125°C. This is explicitly specified in the Electrical Characteristics table under "Input Bias Current" with conditions TA = –40°C to +125°C. At +25°C, typical input bias current is ±0.1pA, and the maximum is ±0.8pA. The ±800pA limit ensures predictable performance in high-impedance sensor interfaces such as photodiode transimpedance amplifiers deployed in automotive or industrial environments.
Can the MAX9638AVB+ be used as a transimpedance amplifier for photodiode applications?
Yes, the MAX9638AVB+ is explicitly designed and characterized for photodiode transimpedance amplifier applications. Its ultra-low 0.1pA typical input bias current, low 0.9fA/√Hz input current noise, and 2pF input capacitance minimize noise and offset errors. The device's 1.5MHz gain bandwidth supports fast pulse detection (e.g., in pulse oximetry), and its stability with 300pF capacitive loads accommodates typical photodiode junction capacitance. Application circuits and layout guidance are provided in the MAX9638AVB+ datasheet Figures 3 and 10–12.
MAX9638AVB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-UFQFN
- Packaging:
- Strip
- Product Status:
- Active
- Amplifier Type:
- CMOS
- Number of Circuits:
- 2
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 0.9V/µs
- Gain Bandwidth Product:
- 1.5 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 0.1 pA
- Voltage - Input Offset:
- 2.2 mV
- Current - Supply:
- 36µA (x2 Channels)
- Current - Output / Channel:
- 55 mA
- Voltage - Supply Span (Min):
- 2.1 V
- Voltage - Supply Span (Max):
- 5.5 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-UTQFN (1.4x1.8)
MAX9638AVB+ FAQ
1.How can I place an order for MAX9638AVB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX9638AVB+ 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 MAX9638AVB+ reliable?
The price and inventory of MAX9638AVB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX9638AVB+ is usually 5 days.
3.What payment methods are accepted for MAX9638AVB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX9638AVB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX9638AVB+?
MAX9638AVB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX9638AVB+ 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 MAX9638AVB+?
For technical support, including MAX9638AVB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX9638AVB+ requirements.
6.How does Aetrix verify that MAX9638AVB+ is sourced from the original manufacturer or authorized distributors?
All MAX9638AVB+ 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 MAX9638AVB+ meets industry standards.
7.What is the process for return or replacement of MAX9638AVB+?
All MAX9638AVB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX9638AVB+, 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 MAX9638AVB+ part is unused and in its original packaging.
Return procedure for MAX9638AVB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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