TLA2021IRUGT

The TLA2021IRUGT from Texas Instruments is an ultra-small, cost-optimized 12-bit delta-sigma ADC in a 10-pin X2QFN package measuring just 2.0 x 1.5 mm. It is the single-channel variant of the TLA202x family, designed for system monitoring applications such as supply voltage supervision, battery monitoring, and temperature measurement.

The TLA2021 provides 12-bit resolution with programmable data rates from 128 SPS to 3.3 kSPS. Unlike the TLA2022 and TLA2024, the TLA2021 does not include a programmable gain amplifier (PGA), accepting input signals directly in the range of 0 to VDD (or +/-VDD/2 differential). The internal 2.048V reference sets the full-scale range at +/-2.048V for differential measurements or 0 to 2.048V for single-ended measurements.

The device integrates a voltage reference, oscillator, and I2C interface, requiring no external components. The I2C interface supports standard mode (100 kHz) and fast mode (400 kHz), with three pin-selectable addresses (ADDR pin tied to GND, VDD, or SDA) allowing up to three TLA202x devices on the same I2C bus.

The delta-sigma architecture provides inherent anti-aliasing through oversampling, often eliminating the need for external anti-aliasing filters. The conversion result is available in 16-bit two’s complement format, with the 12-bit conversion result left-justified in the 16-bit word.

Two conversion modes are available: continuous conversion (device continuously converts and updates the result register) and single-shot conversion (device performs one conversion and then powers down). Single-shot mode reduces average power consumption dramatically at low sampling rates. At 128 SPS in single-shot mode, the average current can be as low as a few microamps.

The supply current is 150 uA typical during continuous conversion, with 0.3 mW typical power consumption at 3.3V. The wide 2V to 5.5V supply range covers 2.5V, 3.3V, and 5V logic systems without level translation.

The X2QFN package has a land pattern of only 3 mm2, making the TLA2021 one of the smallest 12-bit ADCs available. This ultra-compact size enables ADC placement directly at the sensor, minimizing noise pickup on sensitive analog traces.

**Delta-Sigma ADC:** The TLA2021 uses a delta-sigma modulator that oversamples the input at a frequency much higher than the output data rate. The modulator produces a 1-bit data stream that is digitally filtered and decimated to produce a 12-bit output word. Higher output data rates (up to 3.3 kSPS) reduce the effective resolution due to less oversampling, while lower data rates (128 SPS) provide the full 12-bit resolution with lower noise.

**Internal Reference:** The 2.048V internal reference sets the ADC full-scale range. For differential measurements, the input range is +/-2.048V. For single-ended measurements (VIN- tied to GND), the input range is 0 to 2.048V. The reference is not accessible externally.

**No PGA:** Unlike the TLA2022 and TLA2024, the TLA2021 has no programmable gain amplifier. The input signal must be within the ADC’s full-scale range. For small-signal measurements, an external amplifier is required, or the TLA2022/TLA2024 with integrated PGA should be used.

**I2C Interface:** The device acts as an I2C slave. The configuration register (16 bits) controls the data rate, conversion mode, and input multiplexer (for TLA2024). The conversion result is read as 2 bytes (16 bits, 12-bit result left-justified). The OS bit starts a single-shot conversion when written with 1, and reads as 1 when conversion is in progress.

**Pin-Selectable Address:** The ADDR pin selects one of three I2C addresses: GND = 0x48, VDD = 0x49, SDA = 0x4A. This allows up to three TLA202x devices on the same I2C bus without address conflicts.