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Texas Instruments LM385PWE4-1-2
- Part No.:
- LM385PWE4-1-2
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM385PWE4-1-2.pdf
- Description:
- IC VREF SHUNT 2% 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,500
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Product details
Overview
LM385PWE4-1-2 from Texas Instruments is a micropower, two-terminal, band-gap shunt voltage reference delivering 1.235 V nominal output with ±20 ppm/°C temperature coefficient, 1.5 Ω max reference impedance over full temperature range, and operating current range of 15 μA to 20 mA. It serves as a precision low-power reference in battery-operated analog signal chains, portable instrumentation, and current-loop transmitters.
For engineers reviewing the LM385PWE4-1-2 datasheet, LM385PWE4-1-2 pinout, LM385PWE4-1-2 application, or LM385PWE4-1-2 equivalent, key selection criteria include its 15–20 mA operating current window, TSSOP-8 package thermal performance (RθJA = 149 °C/W), 60 µV broadband noise (10 Hz–10 kHz), and compatibility with capacitive loads up to 10 µF without instability.
Technical Context
The LM385PWE4-1-2 implements a floating shunt topology with internal band-gap core, high-gain amplifier, and frequency-compensated loop-enabling stable regulation across wide current and temperature ranges without external compensation. Its design tolerates capacitive loading and supports both positive and negative regulation configurations.
It operates exclusively in fixed-voltage reference mode with no adjustability; regulation initiates only after minimum cathode current (15 µA) is supplied. The device features on-chip trimming for tight initial tolerance (±1% or ±2%) and exhibits long-term stability of ±20 ppm/khr at 100 µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 1.235 V nominal at 25°C; ensures accurate biasing for ADCs, DACs, and sensor signal conditioning circuits |
| Initial Tolerance | ±2% (LM385-1.2 grade); enables cost-effective precision without post-calibration in portable meters |
| Temp Coefficient | ±20 ppm/°C over 0°C to 70°C; maintains <±2.5 mV drift across industrial ambient range |
| Ref Impedance | 1.5 Ω max over full temperature range; minimizes load-induced voltage error in varying-current systems |
| Operating Current | 15 μA to 20 mA; supports ultra-low-power sleep modes and high-accuracy active operation in same design |
| Broadband Noise | 60 µV RMS (10 Hz–10 kHz); suitable for 12-bit+ data acquisition without added filtering |
| Long-Term Drift | ±20 ppm/khr at 100 µA; guarantees <±0.1% output change over 5 years in battery-powered applications |
Pinout & Package
TSSOP-8 package (3.00 mm × 4.40 mm body, 1.2 mm max height), RoHS-compliant, green finish, MSL Level-1, lead finish NIPDAU.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Shunt current input / voltage reference node | Current must be sourced into this pin to establish regulated 1.235 V between cathode and anode; primary connection point for feedback and load |
| Anode (Pin 8) | Common reference return / ground reference | Typically connected to system ground or negative rail; defines the 0 V reference for output voltage |
| NC (Pins 2–7) | No internal connection | Unused pins; must remain unconnected-no routing, bypassing, or grounding required |
Key Features
| Feature | Design Value |
|---|---|
| Floating shunt architecture | Enables use in both high-side and low-side regulation topologies without level-shifting circuitry |
| Capacitive load immunity | Stable with ≥10 µF ceramic bypass capacitance-eliminates need for series resistance or external compensation |
| Micropower operation | 15 µA minimum current allows >10-year battery life in always-on portable instruments using coin cells |
| Low dynamic impedance | 1.5 Ω max over 0°C–70°C ensures <15 mV load regulation error even with 10 mA step changes |
| On-chip trimmed accuracy | ±2% initial tolerance reduces calibration overhead in production test for panel meters and field instruments |
Applications
| Portable Meter References | Portable Test Instruments |
|---|---|
Use Scenario: Handheld multimeters requiring stable 1.2 V reference for ADC scaling and autoranging. IC Role / Device Role / Timing Role: Shunt voltage reference providing precise, low-drift reference voltage for successive-approximation ADC front-end. Use Value: Enables 3½-digit accuracy with <±0.5% total error over 0–50°C ambient, extending battery life beyond 2 years on AA cells. |
Use Scenario: Battery-powered oscilloscope probes with integrated signal conditioning and offset calibration. IC Role / Device Role / Timing Role: Precision reference for op-amp bias networks and DAC-controlled offset adjustment. Use Value: Delivers <±1 mV drift over probe operating temperature range, eliminating manual recalibration during field use. |
| Battery-Operated Systems | Current-Loop Instrumentation |
Use Scenario: Wireless sensor nodes (e.g., temperature/humidity) transmitting via LoRaWAN with 10-year target battery life. IC Role / Device Role / Timing Role: Reference source for microcontroller's internal ADC and analog comparator thresholds. Use Value: Draws only 15 µA in sleep mode while maintaining 1.235 V reference integrity-reducing quiescent power by 4× vs. legacy references. |
Use Scenario: 4–20 mA transmitter modules converting sensor outputs for industrial PLC interfaces. IC Role / Device Role / Timing Role: Stable reference for current-sense amplifier gain setting and DAC output scaling. Use Value: Ensures <±0.1% full-scale current accuracy over 0–70°C, meeting IEC 61000-4-2 immunity requirements without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM385BDR-1-2 | SOIC-8 package, ±1% initial tolerance, RθJA = 95 °C/W, same electrical specs | Better thermal performance in PCB-constrained layouts; requires larger board area than TSSOP | Select when higher power dissipation (>150 mW) or tighter initial tolerance is required |
| TLVH431ACDBVR | Adjustable 1.24 V reference, 3-pin SOT-23, 80 µA typical IREF, 0.5 Ω typical ZZ | Requires external resistors for 1.235 V setting; lower impedance but higher quiescent current | Select when adjustable output or lower dynamic impedance justifies added components and layout complexity |
Compared with LM385BDR-1-2, LM385PWE4-1-2 offers superior board-area efficiency and identical electrical behavior in 0–70°C environments; compared with TLVH431ACDBVR, it eliminates resistor network errors and reduces component count but lacks adjustability.
Availability
LM385PWE4-1-2 is available at Aetrix Electronics and suitable for portable meter references, battery-operated systems, and current-loop instrumentation requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LM385PWE4-1-2 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
Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision analog ICs and industrial-grade reference solutions.
The LMx85-1.2 family-including LM385PWE4-1-2-is designed specifically for micropower, high-stability voltage referencing in portable, battery-constrained, and industrial measurement systems where low drift and capacitive-load robustness are critical.
FAQ
What is the minimum operating current for LM385PWE4-1-2?
The LM385PWE4-1-2 requires a minimum cathode current of 15 µA to achieve proper regulation. Below this threshold, output voltage deviates significantly from 1.235 V, and long-term stability degrades. This value is specified in the Electrical Characteristics table under IZ(min) for the LM385-1.2 grade, and applies directly to LM385PWE4-1-2.
Can LM385PWE4-1-2 replace LM285-1.2 in existing designs?
LM385PWE4-1-2 is not a direct drop-in replacement for LM285-1.2 due to differing operating temperature range (0°C–70°C vs. –40°C–85°C) and minimum current (15 µA vs. 10 µA). However, in applications operating within 0°C–70°C and sourcing ≥15 µA, LM385PWE4-1-2 provides identical reference voltage and improved thermal performance in TSSOP-8 packaging.
What is the maximum capacitive load LM385PWE4-1-2 can drive stably?
The LM385PWE4-1-2 is characterized for stable operation with ≥10 µF ceramic bypass capacitance on the cathode node, per TI's Layout Guidelines. No series resistance or external compensation is needed. This capacitive load immunity simplifies PCB layout and improves transient response in portable instrumentation where EMI suppression is critical.
Does LM385PWE4-1-2 require a heatsink in standard PCB layouts?
No heatsink is required for LM385PWE4-1-2 under typical conditions. With RθJA = 149 °C/W and maximum power dissipation of ~24 mW (at 20 mA × 1.235 V), junction temperature rise remains <4°C above ambient in standard FR-4 layouts with minimal copper. Thermal relief is unnecessary unless ambient exceeds 70°C or power approaches 30 mW.
How does the 60 µV broadband noise of LM385PWE4-1-2 impact 12-bit ADC accuracy?
The 60 µV RMS noise (10 Hz–10 kHz) of LM385PWE4-1-2 contributes <±0.2 LSB error to a 12-bit ADC with 1.235 V full-scale range (LSB = 302 µV), well within typical INL specifications. This enables direct coupling to precision SAR ADCs without additional low-noise buffering-reducing bill-of-materials and board space in portable data loggers.
LM385PWE4-1-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Series:
- -
- Packaging:
- Tray
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Fixed
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- -
- Current - Output:
- 20 mA
- Tolerance:
- ±2%
- Temperature Coefficient:
- 20ppm/°C Typical
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 60µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 15 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
LM385PWE4-1-2 FAQ
1.How can I place an order for LM385PWE4-1-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM385PWE4-1-2 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 LM385PWE4-1-2 reliable?
The price and inventory of LM385PWE4-1-2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM385PWE4-1-2 is usually 5 days.
3.What payment methods are accepted for LM385PWE4-1-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM385PWE4-1-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM385PWE4-1-2?
LM385PWE4-1-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM385PWE4-1-2 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 LM385PWE4-1-2?
For technical support, including LM385PWE4-1-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM385PWE4-1-2 requirements.
6.How does Aetrix verify that LM385PWE4-1-2 is sourced from the original manufacturer or authorized distributors?
All LM385PWE4-1-2 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 LM385PWE4-1-2 meets industry standards.
7.What is the process for return or replacement of LM385PWE4-1-2?
All LM385PWE4-1-2 units undergo pre-shipment inspection (PSI). If there is an issue with LM385PWE4-1-2, 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 LM385PWE4-1-2 part is unused and in its original packaging.
Return procedure for LM385PWE4-1-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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