PGA308| Datasheet

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A308
PGA3

PGA308

www.ti.com ...................................................................................................................................................................................................... SBOS440 JULY 2008

Single-Supply, Auto-Zero Sensor Amplifier with Programmable Gain and Offset
1

FEATURES
Digital Calibration for Bridge Sensors Offset Select: Coarse and Fine Gain Select: Coarse and Fine Bridge Fault Monitor Input Mux for Lead Swap Over/Under Scale Limits DOUT/ VOUT Clamp Function Seven Banks OTP Memory One-Wire Digital UART Interface Operating Voltage: +2.7V to +5.5V Temperature Range: 40 C to +125 C MSOP-10 and 3mm x 4mm DFN-10 Packages

DESCRIPTION
The PGA308 is a programmable analog sensor signal conditioner. The analog signal path amplifies the sensor signal and provides digital calibration for offset and gain. Calibration is done via the 1W pin, a digital One-Wire, UART-compatible interface. For three-terminal sensor modules, 1W may be connected to VOUT and the assembly programmed through the VOUT pin. Gain and offset calibration parameters are stored onboard in seven banks of one-time programmable (OTP) memory. The power-on reset (POR) OTP bank may be programmed a total of four times. The all-analog signal path contains a 2x2 input multiplexer (mux) to allow electronic sensor lead swapping, a coarse offset adjust, an auto-zero programmable gain instrumentation amplifier (PGA), a fine gain adjust, a fine offset adjust, and a programmable gain output amplifier. Fault monitor circuitry detects and signals sensor burnout, overload, and system fault conditions. Over/under-scale limits provide additional means for system level diagnostics. The dual-use D
OUT/VCLAMP pin can be used as a programmable digital output or as a VOUT over-voltage clamp. For detailed application information, see the PGA308 User's Guide (SBOU069) available for download at www.ti.com.
VS 4 VREF 10 DOUT/VCLAMP 1 Digital Interface (One-Wire) VREF Coarse Offset 7-Bit + Sign DAC VREF DOUT Select OTP (7 Banks) RAM 2

APPLICATIONS
Bridge Sensors Remote 4-20mA Transmitters Strain, Load, Weigh Scales Automotive Sensors

EVALUATION TOOLS
PGA308EVM (Hardware and Software) Calibration and Configuration Sensor Emulation
VEXC

PGA308

Fine Offset 16-Bit DAC VREF Output Gain

Overscale 3-Bit DAC Ref(1)

8 7 VFB VSJ

VIN1

5 Input Mux Fault Monitor Auto-Zero PGA 16-Bit DAC

Output Gain Select

Output Amplifier

Scale Limit

VOUT

Bridge Sensor

VIN2

6 Front-End Gain Select 3 GND

Ref(1) 3-Bit DAC Underscale

Fine Gain

NOTE: (1) Ref = VREF or VS selectable.

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Copyright 2008, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.