PGA308 Datasheet, PDF (1/24 Pages) Texas Instruments – Single-Supply, Auto-Zero Sensor Amplifier

PGA308
PGA308
PGA308
www.ti.com ...................................................................................................................................................................................................... SBOS440 – JULY 2008
Single-Supply, Auto-Zero Sensor Amplifier
with Programmable Gain and Offset
FEATURES
1
•2 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
• D_OUT/ V_OUT 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
APPLICATIONS
• Bridge Sensors
• Remote 4-20mA Transmitters
• Strain, Load, Weigh Scales
• Automotive Sensors
EVALUATION TOOLS
• PGA308EVM (Hardware and Software)
– Calibration and Configuration
– Sensor Emulation
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 V_OUT and the assembly programmed
through the V_OUT 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/V_CLAMP
pin can be used as a programmable digital output or
as a V_OUT over-voltage clamp.
For detailed application information, see the PGA308
User's Guide (SBOU069) available for download at
www.ti.com.
V_EXC
PGA308
Coarse Offset
7-Bit + Sign
DAC
V_REF
V_S
4
V_REF
10
D_OUT/V_CLAMP
1
V_REF
D_OUT
Select
Fine Offset
16-Bit
DAC
V_REF
Overscale
3-Bit
DAC
Output Gain
Ref⁽¹⁾
V_IN1 5
Bridge
Sensor
V_IN2 6
Input
Mux
Fault
Monitor
Front-End
Gain Select
Auto-Zero
PGA
3
GND
Output
Gain
Select
16-Bit
DAC
Fine Gain
Output
Amplifier
Ref⁽¹⁾
3-Bit
DAC
Underscale
NOTE: (1) Ref = V_REF or V_S selectable.
Digital Interface
(One-Wire)
2
1W
OTP
(7 Banks)
RAM
Scale
Limit
8
V_FB
7
V_SJ
9
V_OUT
1
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Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
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.
Copyright © 2008, Texas Instruments Incorporated