Microchip Technology AT24C04B-PU

Overview

AT24C04B-PU from Microchip Technology (formerly Atmel) is a 4-kbit two-wire serial EEPROM IC used for nonvolatile data storage in embedded control and configuration systems. It provides 512 × 8-bit memory organization, operates from 1.8 V to 5.5 V, supports up to 1 MHz I²C clock at 5 V, and features hardware write protection via the WP pin. It is commonly deployed in industrial sensor calibration, power supply configuration, and firmware parameter storage.

For engineers reviewing the AT24C04B-PU datasheet, AT24C04B-PU pinout, AT24C04B-PU application, or AT24C04B-PU equivalent, key selection criteria include its 1.8–5.5 V voltage range, 16-byte page write capability, 1 million write endurance, 100-year data retention, and compatibility with standard I²C bus timing at multiple voltage levels.

Technical Context

The AT24C04B-PU implements a standard two-wire (I²C-compatible) serial interface with Schmitt-triggered, noise-filtered SCL and SDA inputs. It uses a 9-bit internal word address counter for random access and supports byte-write and 16-byte page-write operations with self-timed internal write cycles (≤5 ms).

Hardware addressing is enabled via A2 and A1 pins (A0 is NC), allowing up to four AT24C04B-PU devices on a single bus. The WP pin enables full-array hardware write protection when pulled high, and the device enters low-power standby mode after STOP condition receipt or power-up.

Key Specifications

Pinout & Package

AT24C04B-PU is supplied in an 8-lead PDIP (Plastic Dual Inline Package), 0.300" wide body, with through-hole mounting. Pin 1 is marked by a notch or dot at the top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with AT24C04B-PU, 24LC04B-I/P offers identical electrical and mechanical compatibility, while CAT24C04WI-GT3 trades through-hole convenience for surface-mount scalability - both maintain the same 1-million-cycle endurance and 100-year data retention critical for industrial firmware storage.

Availability

AT24C04B-PU is available at Aetrix Electronics and suitable for industrial sensor calibration, power supply configuration, and firmware parameter storage requiring stable component supply across extended product lifecycles.

Supply support for AT24C04B-PU 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

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and communications markets.

The AT24C04B-PU belongs to Microchip's legacy AT24Cxx serial EEPROM product line, designed specifically for reliable, low-power, I²C-based configuration and calibration data storage in resource-constrained embedded systems.

FAQ

What is the maximum I²C clock frequency supported by the AT24C04B-PU?

The AT24C04B-PU supports up to 1 MHz I²C clock frequency when operated at VCC = 5.0 V. At lower supply voltages - 1.8 V, 2.5 V, or 2.7 V - the maximum clock frequency is 400 kHz. These limits are defined in the AC characteristics table and ensure reliable data setup/hold timing across voltage ranges. The AT24C04B-PU maintains full protocol compliance under these conditions without requiring external clock dividers or firmware adaptation.

How many AT24C04B-PU devices can share the same I²C bus?

Up to four AT24C04B-PU devices can operate on a single I²C bus using hardware address pins A2 and A1. A0 is a no-connect pin and does not participate in addressing. Each device's unique combination of A2/A1 logic levels (00, 01, 10, 11) selects one of four possible 7-bit device addresses (1010000, 1010001, 1010010, 1010011). This allows multi-node configuration storage without software address management. The AT24C04B-PU does not require external address jumpers beyond A2/A1 wiring.

Does the AT24C04B-PU require an external pull-up resistor on the SDA line?

Yes, the AT24C04B-PU requires external pull-up resistors on both SDA and SCL lines because its I/O pins are open-drain. Typical values range from 1.8 kΩ (for 1 MHz operation at 5 V) to 10 kΩ (for 400 kHz at 1.8 V), selected based on bus capacitance and speed requirements. The AT24C04B-PU's internal circuitry does not provide active pull-ups, and omission of external resistors will prevent proper I²C communication. Pull-up to VCC is mandatory - not to a separate voltage rail.

What happens when the WP pin of the AT24C04B-PU is tied to VCC?

When the WP pin of the AT24C04B-PU is tied to VCC, the entire memory array is placed in hardware write-protected mode: all write operations (byte write, page write, and write-enable commands) are inhibited, and the device responds only to read commands. This protection remains active regardless of I²C address or command sequence. To restore write capability, WP must be driven low (to GND) - no software unlock sequence is required. This behavior is guaranteed across the full operating temperature and voltage range of the AT24C04B-PU.

Is the AT24C04B-PU compatible with standard I²C protocol implementations?

Yes, the AT24C04B-PU is fully compliant with the standard Philips I²C-bus specification, including START/STOP conditions, 7-bit addressing, ACK/NACK handshaking, and repeated START support. It implements standard I²C timing parameters (tLOW, tHIGH, tSU.STA, etc.) as specified in its datasheet for both 400 kHz and 1 MHz modes. No special controller firmware or bit-banged I/O is required - it works with any standard I²C master peripheral, including those in STM32, PIC, and ESP32 microcontrollers. The AT24C04B-PU does not require custom drivers beyond generic I²C EEPROM support libraries.