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Analog Devices Inc./Maxim Integrated MAX9938WEBS+T
- Part No.:
- MAX9938WEBS+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 4-WFBGA, CSPBGA
- Datasheet:
-
MAX9938WEBS+T.pdf
- Description:
- IC CURRENT SENSE 1 CIRCUIT 4UCSP
- Quantity:
- Payment:
- Shipping:
Inventory:22,500
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Product details
Overview
The MAX9938WEBS+T from Maxim Integrated is a unidirectional high-side current-sense amplifier with 200V/V fixed gain, 500μV (max) input offset voltage, <0.5% (max) gain error, and ultra-low 1μA (max) quiescent supply current. It operates over a +1.6V to +28V input common-mode range and delivers a voltage output ideal for precision battery-current monitoring in portable power management systems.
For engineers reviewing the MAX9938WEBS+T datasheet, MAX9938WEBS+T pinout, MAX9938WEBS+T application, or MAX9938WEBS+T equivalent, this device is selected for low-voltage-drop, high-accuracy sensing in space-constrained, battery-powered designs where input offset, gain stability, and supply current directly impact measurement fidelity and runtime.
Technical Context
The MAX9938WEBS+T uses a BiCMOS architecture with matched internal gain resistors (R1 = 100Ω, ROUT = 20kΩ) to achieve its 200V/V gain. Its high-voltage p-channel FET input stage enables operation down to 1.6V common-mode voltage while maintaining rail-to-rail output swing relative to VRS−.
It features no separate VCC pin - supply is derived solely from the sensed rail (RS+/RS−), eliminating auxiliary bias requirements. Output is protected by a 6V clamp and 7mA current limit, and the device remains stable with any external capacitive load on OUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain | 200V/V - sets full-scale output to 4.0V for 20mV sense voltage, enabling high-resolution ADC interfacing with minimal resistor IR drop. |
| Input Offset Voltage | ±500μV (max) - contributes ≤100μV error at 20mV VSENSE, supporting accurate sub-1% current measurement at low loads. |
| Gain Error | ±0.8% (max) - limits total gain-induced error to ±160μV at 20mV VSENSE, critical for calibrated battery fuel gauging. |
| Supply Current | 1μA (max) - enables multi-year operation in always-on battery monitoring without measurable drain impact. |
| Common-Mode Range | +1.6V to +28V - supports direct sensing from Li-ion (2.5–4.2V), 12V automotive, and 24V industrial rails without level-shifting. |
| Small-Signal Bandwidth | 15kHz - sufficient for DC/low-frequency load transients (e.g., CPU burst current), not intended for switching-regulator ripple rejection. |
| Output Resistance | 14.0–26.4kΩ - defines RC time constant with external filter caps; requires low-capacitance ADC inputs or buffer for fast settling. |
Pinout & Package
MAX9938WEBS+T is packaged in a 4-bump, 1mm × 1mm × 0.6mm UCSP (Ultra-Compact Silicon Package) with bottom-side bumps. This RoHS-compliant, lead-free package is optimized for high-density portable PCBs and reflow-compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | RS+ | High-side connection to power rail; carries full load current and defines common-mode reference point. |
| A2 | RS− | Low-side connection to sense resistor; Kelvin-sense node minimizing trace resistance error. |
| B1 | GND | Dedicated ground return for internal bias and output stage; must be routed with low impedance to minimize noise coupling. |
| B2 | OUT | Voltage output proportional to (VRS+ − VRS−) × 200; drives ADC input or comparator with 120mV full-scale compliance at 3.6V supply. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 1μA (max) - enables continuous battery monitoring in sleep mode without compromising system standby lifetime. |
| Matched internal gain resistors | R1 = 100Ω, ROUT = 20kΩ - ensures 200V/V gain accuracy independent of external component tolerances or temperature drift. |
| Input common-mode range | +1.6V to +28V - allows direct sensing from depleted Li-ion cells (≥1.6V) through 24V industrial supplies without external bias networks. |
| Output voltage clamp | 6V absolute max - protects downstream ADC or microcontroller I/O pins during overvoltage fault conditions on RS+ or RS−. |
| Stable with capacitive loads | No external compensation required - simplifies layout when driving sample-and-hold capacitors or long traces to remote ADCs. |
Applications
| Smartphone Battery Monitoring | USB-C Power Delivery Gauging |
|---|---|
Use Scenario: Real-time charge/discharge current tracking in smartphones with dual-cell Li-ion packs operating down to 2.8V per cell. IC Role / Device Role / Timing Role: High-side current-sense amplifier converting mV-level sense voltage into scalable analog output for fuel-gauge MCU ADC. Use Value: 500μV offset enables ±1% full-scale accuracy at 20mV VSENSE, supporting precise coulomb counting across 0–100% SOC without calibration drift. |
Use Scenario: Input current measurement in USB-C PD sink controllers managing up to 100W (20V/5A) with dynamic voltage negotiation. IC Role / Device Role / Timing Role: Unidirectional high-side monitor on the 5–20V VBUS line, feeding real-time current data to PD policy engine. Use Value: 1.6V–28V common-mode range covers entire USB PD specification; 200V/V gain yields 1V output at 5mV VSENSE, matching typical 12-bit ADC LSB resolution. |
| Portable Medical Device Power Management | Industrial IoT Sensor Node Battery Supervision |
Use Scenario: Continuous current logging in handheld ultrasound or glucose meters powered by single-cell Li-ion (3.0–4.2V). IC Role / Device Role / Timing Role: Precision current sensor interfaced to low-power microcontroller ADC for battery health diagnostics and usage analytics. Use Value: 1μA quiescent current extends usable battery life beyond 5 years in always-on monitoring mode without sacrificing measurement resolution. |
Use Scenario: Long-life battery supervision in wireless vibration sensors deployed in remote industrial equipment with 10-year target service life. IC Role / Device Role / Timing Role: High-side current monitor on primary Li-SOCl₂ cell (3.6V nominal), reporting self-discharge and load pulses to LoRaWAN transceiver. Use Value: 500μV offset and 0.8% gain error ensure <±2% current reading accuracy over -40°C to +85°C, critical for predictive maintenance algorithms. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-side current-sense amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA219BIDR | I²C digital output; 0.1% gain error; 100μA supply current; 26V common-mode; 12-bit integrated ADC. | Requires no external ADC but adds firmware overhead; less suitable for analog-domain control loops or ultra-low-power wake-up triggers. | Select when digital interface, integrated ADC, and higher gain accuracy outweigh 100× higher supply current and larger 2.9mm × 2.8mm SOIC package. |
| MAX40056AUT+T | 200V/V gain; 125μV offset; 0.2% gain error; 15μA supply current; 1.2V–28V common-mode; SOT23-5 package. | Lower offset and gain error improve precision but 15μA supply current reduces battery life in always-on use cases. | Select when measurement accuracy dominates power budget, and SOT23-5 footprint compatibility is required over UCSP miniaturization. |
Compared with MAX9938WEBS+T, INA219BIDR trades ultra-low power and analog simplicity for digital integration and higher current draw, while MAX40056AUT+T improves precision at the cost of 15× higher quiescent current and larger footprint - making MAX9938WEBS+T optimal for size- and runtime-critical portable systems.
Availability
MAX9938WEBS+T is available at Aetrix Electronics and suitable for smartphone battery monitoring, USB-C power delivery gauging, and portable medical device power management requiring stable component supply across multi-year production cycles.
Supply support for MAX9938WEBS+T 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) is a U.S.-based semiconductor company specializing in precision analog, mixed-signal, and power-management ICs for demanding industrial, computing, and portable applications.
The MAX9938 family was designed specifically for high-accuracy, ultra-low-power current sensing in battery-operated portable electronics, emphasizing minimal voltage burden, wide common-mode tolerance, and miniature packaging.
FAQ
What is the maximum input common-mode voltage supported by the MAX9938WEBS+T?
The MAX9938WEBS+T supports an input common-mode voltage range of +1.6V to +28V. This allows it to operate directly on low-voltage Li-ion cells (down to 1.6V) and higher-voltage industrial rails without external level-shifting circuitry. The upper limit of +28V provides margin for transient spikes in 24V systems, and the specification is guaranteed over the full -40°C to +85°C temperature range.
Does the MAX9938WEBS+T require an external power supply pin?
No, the MAX9938WEBS+T does not have a dedicated VCC pin. It derives all operating power from the sensed voltage applied across RS+ and RS−, making it a true single-supply, high-side sensing solution. This eliminates the need for auxiliary bias rails and simplifies system power architecture - especially valuable in space- and cost-constrained portable designs where every component counts.
What is the full-scale sense voltage range compatible with the 200V/V gain of the MAX9938WEBS+T?
For optimal linearity and accuracy, the MAX9938WEBS+T's 200V/V gain is designed for full-scale sense voltages between 2.5mV and 15mV, as confirmed in the datasheet's gain-error test conditions. At 3.6V minimum RS+ voltage, a 15mV VSENSE yields ~3.0V output, staying within the specified output swing limits. Using larger sense voltages risks saturation or reduced dynamic range due to VOH headroom constraints.
Can the MAX9938WEBS+T be used in bidirectional current sensing applications?
The MAX9938WEBS+T is a unidirectional high-side current-sense amplifier and cannot directly measure reverse current flow. However, the datasheet shows a bidirectional application (Figure 3) using two MAX9938 devices - one for charge current (RS+ to battery+, RS− to load) and another for discharge - with outputs referenced to GND. This discrete dual-amplifier approach achieves bidirectional capability while retaining the precision and low-power benefits of the MAX9938WEBS+T.
What package type and dimensions does the MAX9938WEBS+T use?
The MAX9938WEBS+T uses a 4-bump UCSP (Ultra-Compact Silicon Package) measuring 1.0mm × 1.0mm × 0.6mm with bottom-side solder bumps. This RoHS-compliant, lead-free package is optimized for high-density portable PCBs and supports standard reflow soldering profiles. Its footprint is significantly smaller than equivalent SOT23-5 or μDFN packages, enabling placement in tight spaces such as smartphone battery compartments or wearable device edge regions.
MAX9938WEBS+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 4-WFBGA, CSPBGA
- Packaging:
- Bulk
- Product Status:
- Active
- Amplifier Type:
- Current Sense
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- -
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 60 kHz
- Current - Input Bias:
- -
- Voltage - Input Offset:
- 100 µV
- Current - Supply:
- 1.1µA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 1.6 V
- Voltage - Supply Span (Max):
- 28 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 4-UCSP (1.05x1.05)
MAX9938WEBS+T FAQ
1.How can I place an order for MAX9938WEBS+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX9938WEBS+T 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 MAX9938WEBS+T reliable?
The price and inventory of MAX9938WEBS+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX9938WEBS+T is usually 5 days.
3.What payment methods are accepted for MAX9938WEBS+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX9938WEBS+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX9938WEBS+T?
MAX9938WEBS+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX9938WEBS+T 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 MAX9938WEBS+T?
For technical support, including MAX9938WEBS+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX9938WEBS+T requirements.
6.How does Aetrix verify that MAX9938WEBS+T is sourced from the original manufacturer or authorized distributors?
All MAX9938WEBS+T 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 MAX9938WEBS+T meets industry standards.
7.What is the process for return or replacement of MAX9938WEBS+T?
All MAX9938WEBS+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX9938WEBS+T, 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 MAX9938WEBS+T part is unused and in its original packaging.
Return procedure for MAX9938WEBS+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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