LM8500HLQ9

Overview

The LM8500HLQ9 is a four-wire resistive touchscreen controller manufactured by Texas Instruments (formerly National Semiconductor). It features an integrated 10-bit A/D converter capable of sampling up to 500 coordinate pairs per second. The device communicates via a UART interface at 38400 bps and includes internal non-volatile memory for storing calibration data and configuration settings. Operating with a 5V supply, it incorporates a high brownout reset feature (4.17V–4.5V) and supports clock frequencies of 3.27 MHz or 10 MHz. The component is housed in a 44-pin LLP package and operates within a temperature range of 0°C to +70°C.

Feature Summary

• Integrated 10-bit A/D converter with maximum speed of 500 coordinate pairs per second
• Built-in UART interface operating at 38400 bps for host communication
• Internal non-volatile storage for calibration points and controller configurations
• High Brownout Reset (BOR) trip level between 4.17V and 4.5V
• Low power standby current typically less than 2 µA

Applications

• Personal Digital Assistants
• Smart Hand-Held Devices
• Touch Screen Monitors
• Point-of-Sales Terminals
• KIOSK Systems
• Cell Phones

Procurement Notes

Verify the specific suffix 'H' indicates the 44-pin package variant and 'LQ9' denotes the LLP package with 0°C to +70°C operating temperature. Confirm that the high brownout voltage threshold aligns with the system's 5V power rail requirements. Ensure the UART baud rate configuration matches the host processor settings before integration.

Selection Notes

Select the LM8500HLQ9 when a 5V operating voltage and high brownout protection are required. This model supports both 3.27 MHz and 10 MHz oscillator frequencies via the CLK_SET pin. Choose this part over the LM8300 if the application demands a higher brownout trip voltage (4.17V–4.5V vs 2.7V–2.9V). Ensure the design accommodates the 44-pin LLP footprint.

Part Context

The LM8500 series belongs to the family of four-wire resistive touchscreen controllers from National Semiconductor, now Texas Instruments. It is functionally similar to the LM8300 but differs in its brownout reset voltage threshold and supported clock speeds. The LM8500 is designed for applications requiring robust operation on a 5V supply with automatic wake-up capabilities from low-power standby modes.

Replacement Considerations

The LM8300 is a related device within the same datasheet but features a low brownout voltage (2.7V–2.9V) and only supports 3.27 MHz operation. Direct substitution requires verifying that the lower brownout threshold and fixed clock speed of the LM8300 meet the system requirements.