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Texas Instruments LM3420M5X-8.4
- Part No.:
- LM3420M5X-8.4
- Manufacturer:
- Texas Instruments
- Category:
- Battery Chargers
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3420M5X-8.4.pdf
- Description:
- IC BATT CNTL LI-ION 2CEL SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,871
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Product details
Overview
LM3420M5X-8.4 from Texas Instruments (formerly National Semiconductor) is a fixed-output shunt-mode lithium-ion battery charge controller IC designed for precise end-of-charge voltage regulation in 2-cell (8.4 V) battery packs. It integrates a precision bandgap reference (±0.5% initial tolerance, A-grade), internally compensated op amp, open-emitter NPN output transistor (15 mA drive), and internal feedback resistor (181 kΩ). It enables constant-current/constant-voltage charging in linear or switching charger topologies.
For engineers reviewing the LM3420M5X-8.4 datasheet, LM3420M5X-8.4 pinout, LM3420M5X-8.4 application, or LM3420M5X-8.4 equivalent, key selection criteria include its 8.4 V regulation accuracy, SOT23-5 package footprint, 85 µA quiescent current, open-emitter output drive capability, and temperature-stable bandgap reference with curvature correction.
Technical Context
The LM3420M5X-8.4 implements a shunt-regulator architecture where the IN pin senses battery voltage and the OUT pin sources current to control an external pass element (e.g., BJT, MOSFET, or optocoupler). Its error amplifier compares sensed voltage against an internal 8.4 V reference and drives the NPN output to maintain regulation.
Compensation is performed externally via the COMP pin, connected to the inverting input of the amplifier. The internal feedback resistor (181 kΩ, min/max 135–227 kΩ) sets gain and affects phase margin; stability is verified using load-step response and Bode analysis per the 8.4 V version's published curves.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Regulation Voltage | 8.4 V nominal; ±0.5% (A-grade) or ±1% (standard) tolerance ensures accurate 2-cell Li-ion full-charge detection without external trimming. |
| Output Drive | Open-emitter NPN capable of sourcing up to 15 mA - sufficient to directly drive base/gate of external power transistors or optocouplers in CC/CV loop. |
| Quiescent Current | 85 µA typical - minimizes parasitic discharge during standby, critical for battery-powered systems with long idle periods. |
| Operating Temp | −40°C to +85°C ambient - validated for industrial and portable equipment environments without derating. |
| Package | SOT23-5 (M5) - sub-miniature surface-mount footprint (2.9 mm × 1.6 mm) enabling compact, high-density PCB layouts. |
| Input Voltage Max | 20 V absolute maximum - supports wide-input DC supplies (e.g., 12 V adapters, automotive-derived rails) with headroom for transient spikes. |
| Internal Rf | 181 kΩ (typical), 135–227 kΩ (min–max) - defines compensation network gain; impacts loop stability and must be considered in closed-loop design. |
Pinout & Package
The LM3420M5X-8.4 is housed in a 5-lead SOT23-5 surface-mount package (NS package code MF05A), with pin 1 marked by a dot or notch. Thermal performance is optimized when pin 5 (GND) is soldered to a large copper pour for heat transfer.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Battery voltage sense input | Connects directly to battery positive terminal; voltage at this pin is compared to internal 8.4 V reference to initiate regulation. |
| 2 (GND) | Analog ground reference | Common return for internal bandgap, amplifier, and external feedback; must be low-impedance connection to minimize noise and offset errors. |
| 3 (OUT) | Open-emitter NPN output | Sources up to 15 mA to control external pass device; requires external pull-up or collector load to function as active-low driver. |
| 4 (COMP) | Inverting input of error amplifier | Externally accessible for loop compensation (e.g., capacitor to OUT); enables stability tuning across load and topology variations. |
| 5 (NC) | No internal connection | Not bonded internally; recommended to solder to PCB ground plane solely for mechanical stability and thermal conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Precision 8.4 V reference | 0.5% initial tolerance (A-grade) with curvature-corrected bandgap ensures stable end-of-charge voltage over −40°C to +85°C. |
| Integrated compensation node | COMP pin provides direct access to amplifier inverting input, enabling single-capacitor loop stabilization without external op-amp. |
| Low-quiescent-current operation | 85 µA typical supply current minimizes battery self-discharge during maintenance or storage mode. |
| Shunt-mode architecture | Eliminates need for high-side current sensing or complex feedback dividers; simplifies integration into both linear and switching charger designs. |
| Robust voltage rating | 20 V absolute maximum input withstands common DC supply transients and enables use with unregulated wall adapters or automotive inputs. |
Applications
| Portable Medical Devices | Industrial Handheld Terminals |
|---|---|
Use Scenario: Rechargeable 2-cell Li-ion battery pack in a battery-powered ECG monitor requiring safe, repeatable full-charge termination. IC Role / Device Role / Timing Role: Shunt regulator providing precise 8.4 V reference and feedback drive to control external MOSFET in constant-voltage stage. Use Value: Enables compliance with IEC 62368-1 battery safety requirements through ±0.5% regulation accuracy and low 85 µA quiescent drain. | Use Scenario: Ruggedized barcode scanner with hot-swap battery support and extended field operation. IC Role / Device Role / Timing Role: Core voltage-sense and control element in a switching-based CC/CV charger using LM2575-ADJ and LM358. Use Value: Delivers stable 8.4 V regulation across −20°C to +60°C operating range while maintaining <15 mA output drive for optocoupler isolation. |
| Wireless Power Tools | Emergency Lighting Systems |
Use Scenario: High-current (≥2 A) 2-cell Li-ion pack in cordless drill with fast-charge capability and thermal foldback interface. IC Role / Device Role / Timing Role: Precision voltage reference and loop controller interfacing with external current-sense amplifier and power FET gate driver. Use Value: Supports accurate CV transition at 8.4 V with minimal temperature drift, reducing risk of overcharge during high-ambient-temperature operation. | Use Scenario: Backup LED lighting system with integrated Li-ion backup battery and AC/DC adapter input. IC Role / Device Role / Timing Role: End-of-charge detector and feedback driver in linear charger using LM317, ensuring safe float voltage during long-term standby. Use Value: Provides reliable 8.4 V cutoff with <0.1 µA leakage (VIN = VREG −100 mV), preventing battery degradation during months of AC-connected standby. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar lithium-ion charge controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS650230RSLR | Integrated buck charger with USB/AC input management; includes LDOs, I2C interface, and battery gauging - not a standalone shunt controller. | Requires system-level firmware and replaces entire PMIC stack; unsuitable for discrete CC/CV loop reuse. | Select only if migrating to fully integrated power management with digital control and multi-rail support. |
| MAX1555 | Standalone linear Li-ion charger IC with built-in pass transistor, thermal regulation, and status outputs - no external pass device needed. | Lacks programmable voltage setpoint; fixed 4.2 V output - incompatible with 2-cell (8.4 V) configurations. | Use only for single-cell applications; not a functional substitute for LM3420M5X-8.4's 8.4 V shunt control architecture. |
Compared with TPS650230RSLR and MAX1555, the LM3420M5X-8.4 offers unique flexibility as a discrete, voltage-programmed shunt controller - enabling custom thermal design, topology choice (linear/switching), and reuse of legacy pass elements without firmware dependency.
Availability
LM3420M5X-8.4 is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld terminals, wireless power tools, and emergency lighting systems requiring stable component supply and long-term production continuity.
Supply support for LM3420M5X-8.4 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 (TI) acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for legacy analog products including the LM3420 series.
The LM3420 product line was designed specifically for precision, low-power, discrete Li-ion battery charge control - targeting applications where flexibility, thermal manageability, and minimal bill-of-materials outweigh the benefits of highly integrated solutions.
FAQ
What is the regulation voltage accuracy of the LM3420M5X-8.4?
The LM3420M5X-8.4 has a nominal regulation voltage of 8.4 V. For the standard grade (no 'A' suffix), initial tolerance is ±1% over temperature; for the A-grade variant (e.g., LM3420AM5X-8.4), it is ±0.5%. These values are production-tested at 25°C and guaranteed over −40°C to +85°C via statistical correlation. The LM3420M5X-8.4 itself is the standard grade version.
Can the LM3420M5X-8.4 be used for 3-cell or 4-cell Li-ion battery packs?
No - the LM3420M5X-8.4 is factory-trimmed exclusively for 8.4 V output, corresponding to two-series Li-ion cells. For 3-cell (12.6 V) or 4-cell (16.8 V) applications, TI specifies dedicated variants: LM3420M5X-12.6 and LM3420M5X-16.8. Using LM3420M5X-8.4 in higher-voltage configurations will result in premature charge termination and undercharged batteries.
What is the purpose of the NC pin (Pin 5) on the LM3420M5X-8.4?
Pin 5 is a no-connect (NC) terminal with no internal bond wire. Though electrically inactive, National Semiconductor's datasheet explicitly recommends soldering Pin 5 to the PCB ground plane to improve mechanical stability and enhance thermal conduction from the die. This practice helps maintain junction temperature within limits during sustained 15 mA output sourcing.
How does the LM3420M5X-8.4 interface with a switching regulator like the LM2575-ADJ?
The LM3420M5X-8.4 interfaces by sourcing current from its OUT pin into the feedback (FB) node of the LM2575-ADJ, effectively pulling down the FB voltage to regulate output. In constant-voltage mode, it overrides the current-sense loop and forces the LM2575-ADJ to maintain exactly 8.4 V across the battery. This method avoids signal inversion and preserves loop stability when combined with proper compensation on the COMP pin.
Is external compensation required for stable operation of the LM3420M5X-8.4?
Yes - the COMP pin is the inverting input of the internal error amplifier and must be externally compensated for closed-loop stability. TI's application circuits use a single capacitor (e.g., 100 pF to 1 nF) from COMP to OUT. The optimal value depends on the external pass device, load, and topology; stability is confirmed by observing step-load response and verifying phase margin using Bode plots specific to the 8.4 V version.
LM3420M5X-8.4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Battery Chemistry:
- Lithium Ion
- Number of Cells:
- 2
- Current - Charging:
- -
- Programmable Features:
- -
- Fault Protection:
- -
- Charge Current - Max:
- -
- Battery Pack Voltage:
- 8.4V
- Voltage - Supply (Max):
- 20V
- Interface:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM3420M5X-8.4 FAQ
1.How can I place an order for LM3420M5X-8.4 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3420M5X-8.4 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 LM3420M5X-8.4 reliable?
The price and inventory of LM3420M5X-8.4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3420M5X-8.4 is usually 5 days.
3.What payment methods are accepted for LM3420M5X-8.4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3420M5X-8.4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3420M5X-8.4?
LM3420M5X-8.4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3420M5X-8.4 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 LM3420M5X-8.4?
For technical support, including LM3420M5X-8.4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3420M5X-8.4 requirements.
6.How does Aetrix verify that LM3420M5X-8.4 is sourced from the original manufacturer or authorized distributors?
All LM3420M5X-8.4 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 LM3420M5X-8.4 meets industry standards.
7.What is the process for return or replacement of LM3420M5X-8.4?
All LM3420M5X-8.4 units undergo pre-shipment inspection (PSI). If there is an issue with LM3420M5X-8.4, 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 LM3420M5X-8.4 part is unused and in its original packaging.
Return procedure for LM3420M5X-8.4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3420M5X-8.4 Tags
-
BQ21040DBVR
Texas Instruments
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MCP73812T-420I/OT
Microchip Technology
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MCP73831T-2ACI/OT
Microchip Technology
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MCP73832T-2DCI/OT
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MCP73831T-2ATI/OT
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MCP73832T-2ATI/OT
Microchip Technology
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MCP73831T-5ACI/OT
Microchip Technology
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MCP73832T-2ACI/MC
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MCP73831T-2ACI/MC
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