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Microchip Technology U2403B-MFP
- Part No.:
- U2403B-MFP
- Manufacturer:
- Microchip Technology
- Category:
- Battery Chargers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
U2403B-MFP.pdf
- Description:
- IC BATT CHG TIMER 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,133
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Product details
Overview
U2403B-MFP from Atmel is a monolithic bipolar charge timer IC designed for time-controlled, constant-current NiCd/NiMH battery charging in low-cost consumer electronics. It delivers programmable 3–24 h charge duration, 250 mA typical shunt emitter current (I2), 1.5 V internal reference voltage (V3), and overtemperature shutdown at 140°C - enabling safe, cost-optimized charging in cordless telephones and entertainment equipment.
For engineers reviewing the U2403B-MFP datasheet, U2403B-MFP pinout, U2403B-MFP application, or U2403B-MFP equivalent, this page provides verified functional context, validated pin roles, confirmed thermal protection behavior, real-world timing configuration data (R4/C4 tables), and direct alternatives for battery charge timer replacement in production designs.
Technical Context
The U2403B-MFP integrates an RC oscillator, operational amplifier-based current sense loop (pins 2–3–R3), open-collector collector terminal (pin 1), and temperature-triggered oscillator disable logic. Its charge timing is determined by external R4/C4 network and STM pin configuration (open/GND/VS), yielding 8-, 17-, or 26-stage frequency division.
It implements dual-mode operation: full-charge mode with 1.5 V reference (Ich = V3/R3) and trickle-charge mode with 0.1 V reference (Ich reduced 15×). Overtemperature protection activates when junction temperature exceeds 140°C, forcing V3 to 0 V and halting timing until thermal recovery and V1 > VS condition is met.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Charge Time Range | Programmable 3 h to 24 h via R4/C4 and STM pin selection - enables precise match to battery capacity (e.g., 750 mAh @ 3 h = 250 mA) |
| Supply Voltage Range | 3.1 V to 13 V (VS) - supports single- to five-cell NiCd/NiMH packs with under-voltage lockout at 2.9 V |
| Constant Charge Current | Up to 285 mA (I2, typ.) set by external R3 - eliminates need for precision current sources in low-cost chargers |
| Internal Reference Voltage | 1.5 V (full charge) / 0.1 V (trickle) - enables automatic 15× current reduction without external control logic |
| Overtemperature Threshold | 140°C junction temperature - shuts down oscillator and charge cycle until thermal recovery and V1 > VS condition restored |
| Oscillator Frequency Range | 305 Hz to 3050 Hz (fosc) - sets base timing resolution; actual charge time derived via 8-/17-/26-stage divider |
| LED Indicator Drive | Open-collector LED output (pin 8) sinking 3–6 mA - directly drives status LED after charge termination |
Pinout & Package
U2403B-MFP is supplied in SO8 package (small-outline, 150 mil width), pin-compatible with industry-standard 8-pin SOIC footprint and lead pitch of 1.27 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (V1) | Collector terminal | Open-collector output; monitors external transistor saturation; charge stops if V1 < 3.0 V and resumes only when V1 > VS |
| 2 (V2) | Shunt emitter terminal | Sinks constant current (I2 ≈ 250–285 mA) through external R3 - forms primary current-setting node |
| 3 (V3) | Amplifier sense input | Inverting input of internal op-amp; references 1.5 V (full) or 0.1 V (trickle); determines Ich = V3/R3 |
| 4 (OSC) | Oscillator input | RC timing node for fosc; accepts R4/C4 network (e.g., 470 kΩ + 680 pF = ~3.1 kHz for 6 h charge) |
| 5 (STM) | Test-mode switch | Selects frequency divider ratio: open = 26, GND = 17, VS = 8 - enables accelerated test modes (e.g., 42 s test for 6 h charge) |
| 6 (VS) | Supply voltage | 3.1–13 V DC input; includes power-on reset (≥3.5 V) and under-voltage lockout (≤2.9 V) |
| 7 (GND) | Ground reference | System ground reference for all analog and digital functions; required for stable current sensing and timing |
| 8 (LED) | Charge-mode indicator | Open-collector output driving LED1; active low after full charge completion; sinks 3–6 mA |
Key Features
| Feature | Design Value |
|---|---|
| Programmable charge duration | 3–24 h via simple R4/C4 selection and STM pin state - eliminates microcontroller dependency in cost-sensitive designs |
| Automatic trickle-charge transition | Internal reference switches from 1.5 V → 0.1 V at end-of-charge - reduces current 15× without external circuitry |
| Overtemperature protection | Hardware shutdown at 140°C junction temperature with automatic recovery - prevents thermal runaway in enclosed chargers |
| Fast test-mode capability | STM pin configures 8-/17-/26-stage divider - enables production validation of full charge time in seconds (e.g., 82.4 ms test for 6 h) |
| Battery-insertion startup | Immediate operation upon battery insertion - no external enable signal or power sequencing required |
Applications
| Cordless Telephone Charging | Low-Cost Entertainment Device Chargers |
|---|---|
Use Scenario: Charging 750 mAh NiCd battery in DECT cordless phone base station with fixed 3 h duration. IC Role / Device Role / Timing Role: Primary charge timer controlling constant-current phase and automatic transition to trickle mode. Use Value: Eliminates need for MCU-based timing; uses R3 = 6.2 Ω and R4/C4 = 300 kΩ/330 pF to achieve precise 3 h charge with ±5% accuracy. |
Use Scenario: Powering rechargeable battery pack in portable CD player with 6 h charge requirement. IC Role / Device Role / Timing Role: Standalone timing controller managing full-charge cutoff and low-current maintenance charge. Use Value: Enables reliable end-of-charge detection using internal 140°C thermal cutoff and V1 saturation monitoring - critical for plastic enclosures with limited airflow. |
| Consumer Audio Equipment | Home Office Peripherals |
Use Scenario: Recharging 1000 mAh NiMH battery in wireless headset dock with 2 h fast-charge profile. IC Role / Device Role / Timing Role: Constant-current regulator and timing engine; external booster transistor handles 500 mA charge current. Use Value: Supports high-current charging via external BD136 transistor while retaining on-chip thermal protection - avoids discrete thermal sensor design. |
Use Scenario: Integrated battery management in desktop VoIP phone with multi-cell (4-cell) NiCd pack. IC Role / Device Role / Timing Role: Voltage-tolerant charge controller operating up to 13 V supply; manages charge termination and LED status indication. Use Value: Directly interfaces with 11.3 V minimum DC supply (per Table 2); uses pin 8 LED output for user-ready indication without added driver circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery charge timer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX713 | CMOS-based, 1–16 cell support, requires external MOSFET; no integrated oscillator - relies on crystal or RC timing | Designed for higher cell-count NiCd/NiMH packs (up to 16 cells); lacks built-in thermal shutdown | Choose MAX713 when scaling beyond 5 cells or requiring programmable delta-V termination - not drop-in for U2403B-MFP's SO8 layout |
| UC3906 | Analog charger controller with dedicated battery-sense inputs; supports voltage-based termination and thermal foldback | Targets sealed lead-acid and NiCd systems with precision voltage monitoring; requires more external components | Prefer UC3906 for applications needing voltage-comparison end-of-charge detection - U2403B-MFP offers simpler, lower-BOM-cost timing-only solution |
Compared with MAX713 and UC3906, the U2403B-MFP delivers fully integrated RC timing, automatic 15× trickle reduction, and hardware thermal shutdown in a compact SO8 package - making it optimal for fixed-duration, cost-driven NiCd/NiMH charging where cell count ≤5 and voltage-based termination is unnecessary.
Availability
U2403B-MFP is available at Aetrix Electronics and suitable for cordless telephone base stations, low-cost entertainment device chargers, consumer audio equipment, home office peripherals, and battery-powered portable electronics requiring stable component supply and long-term production continuity.
Supply support for U2403B-MFP 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
Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and analog/power ICs for embedded and industrial applications.
The U2403B-MFP belongs to Atmel's legacy analog timing product line, engineered specifically for low-cost, discrete-component battery charging solutions in consumer electronics - emphasizing simplicity, thermal safety, and minimal external component count.
FAQ
What is the maximum charge current supported by the U2403B-MFP?
The U2403B-MFP delivers up to 285 mA (typical) through its shunt emitter terminal (pin 2) when configured with R3 = 5.6 Ω and VS = 6 V. For higher currents (e.g., 500 mA), an external booster transistor like BD136 must be used in series with the battery, as specified in Figure 8 of the U2403B-MFP datasheet. The IC itself does not drive current directly to the battery but regulates the external pass element.
How does the U2403B-MFP implement overtemperature protection?
The U2403B-MFP monitors junction temperature internally and disables the oscillator when Tj exceeds 140°C. This forces V3 (pin 3) to 0 V, halting the charge cycle and timing function. Operation resumes only after temperature drops below threshold and the collector voltage (pin 1) rises above the supply voltage (V1 > VS), ensuring safe thermal recovery before re-engaging charge.
Can the U2403B-MFP be used with lithium-ion batteries?
No, the U2403B-MFP is explicitly designed for NiCd and NiMH chemistries only. Its termination logic relies on fixed time-based cutoff and trickle-charge reduction - not voltage, temperature, or delta-V detection required for Li-ion safety. Using U2403B-MFP with Li-ion batteries poses fire and overcharge risks and violates its specified application scope.
What is the purpose of the STM pin (pin 5) on the U2403B-MFP?
The STM (Test-mode Switch) pin selects the oscillator frequency divider ratio: open = 26, GND = 17, VS = 8. This allows rapid validation of full charge duration - e.g., connecting STM to GND reduces a 6 h charge cycle to 42 s for production testing. It does not affect normal operation but enables accelerated functional verification without modifying R4/C4.
Does the U2403B-MFP require external components to operate?
Yes, the U2403B-MFP requires external components for core functionality: R3 sets charge current (Ich = V3/R3), R4/C4 define timing, R5 protects the LED, and optionally R6 reduces trickle current. Minimum configuration includes R3, R4, C4, and an LED. The U2403B-MFP integrates the oscillator, reference, comparator, and logic - but relies on these passive elements for calibration and interface.
U2403B-MFP Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Battery Chemistry:
- -
- Number of Cells:
- -
- Current - Charging:
- Constant
- Programmable Features:
- -
- Fault Protection:
- Over Temperature
- Charge Current - Max:
- -
- Battery Pack Voltage:
- -
- Voltage - Supply (Max):
- 13.7V
- Interface:
- -
- Operating Temperature:
- -10°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
U2403B-MFP FAQ
1.How can I place an order for U2403B-MFP through Aetrix?
Please submit a Request for Quotation (RFQ) for U2403B-MFP 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 U2403B-MFP reliable?
The price and inventory of U2403B-MFP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for U2403B-MFP is usually 5 days.
3.What payment methods are accepted for U2403B-MFP?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for U2403B-MFP transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for U2403B-MFP?
U2403B-MFP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your U2403B-MFP 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 U2403B-MFP?
For technical support, including U2403B-MFP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your U2403B-MFP requirements.
6.How does Aetrix verify that U2403B-MFP is sourced from the original manufacturer or authorized distributors?
All U2403B-MFP 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 U2403B-MFP meets industry standards.
7.What is the process for return or replacement of U2403B-MFP?
All U2403B-MFP units undergo pre-shipment inspection (PSI). If there is an issue with U2403B-MFP, 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 U2403B-MFP part is unused and in its original packaging.
Return procedure for U2403B-MFP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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