BU21029MUV-E2

Overview

The BU21029MUV-E2 is a 4-wire resistive touch screen controller IC from ROHM Semiconductor. It supports dual-touch detection and gesture recognition for standard 4-wire resistive screens. The device operates on a single power supply ranging from 1.65V to 3.60V. Key electrical specifications include a maximum standby current of 1.0 µA, typical sleep current of 100 µA, and typical operating current of 0.8 mA. It features a 12-bit coordinate resolution and communicates with the host processor via an I2C-like 2-wire serial interface. The component is housed in a VQFN020V4040 package measuring 4.00 mm x 4.00 mm x 1.00 mm.

Feature Summary

• Dual-touch detection capability for 4-wire resistive touch screens
• 12-bit SAR A/D converter resolution for coordinates
• I2C-like 2-wire serial interface with selectable slave addresses (40h/41h)
• Built-in clock oscillator, power-on reset, and auto power-down control

Applications

• Portable information equipment such as smartphones, tablets, and PDAs
• Audio-visual equipment including digital still cameras, digital video cameras, and portable TVs
• PCs and peripheral equipment like laptops, touchscreen monitors, and printers

Procurement Notes

Verify the specific ordering suffix E2 against the manufacturer's latest documentation to confirm compliance status and revision details. Confirm that the VQFN020V4040 package dimensions align with the target PCB footprint requirements. Ensure the host system voltage levels are compatible with the 1.65V to 3.60V operating range.

Selection Notes

Select this component when dual-touch functionality is required for resistive displays. Ensure the host processor supports the I2C protocol for register access. Verify that the application environment stays within the -20°C to +85°C operating temperature range. Consider the low standby current if battery life is a critical design constraint.

Part Context

The BU21029MUV belongs to the BU2102 series of resistive touch screen controllers designed by ROHM Semiconductor. This series focuses on generating data that enables dual touch detection, distinguishing it from standard single-point controllers. The E2 suffix typically denotes environmental compliance or specific manufacturing revisions within the product line.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided source material. Designers should consult ROHM Semiconductor directly for obsolescence management or equivalent component recommendations.

FAQ

How does the BU21029MUV handle dual-touch detection?

The controller generates data based on prearranged touch screen parameters calibrated via registers 0x3 and 0x4. The host processor must execute calibration commands (CF=0101) to match the dual-touch circuit to the specific panel characteristics.

What is the function of the INT pin?

The INT pin provides an active-low interrupt signal to the host processor whenever a touch is detected. In automatic control mode, this signal is generated after the scan of the first touch is completed.

Can the RSTB pin be left unconnected?

No. If the host processor will not actively control the reset function, the RSTB pin must be shorted to VDD to utilize the built-in power-on-reset circuit for initializing the registers upon power-up.