17/19

REV1A

Application Information (Continued)

Typical Application – 8:1 Bridge Sensor Interface

The XR18910 was designed to interface multiple bridge sensors with a microcontroller or FPGA as illustrated in Figure 24.

and vary between sensors. The XR18910 provides the ability to calibrate the bridge offset on each of the 8 bridge sensors

using the on-board DAC.

BRIDGE 8

BRIDGE 1

ADC

µC

OUT

SDA

SCL

IN1+

IN1-

IN8+

IN8-

BRDG

8:1

MUX

LDO

INA /

PGA

CONTROL

PGA

±560mV

OFFSET TRIM

10-BIT

DAC

0.1F

6.8F

+

10k

VCC

VDD

0.1F

6.8F

+

0.1F

4.7k

4.7k

AGND

DGND

10nF

XR18910

Figure 24. 8:1 Bridge Sensor Interface

Layout Considerations

General layout and supply bypassing play major roles in high frequency performance. Follow the steps below as a basis for

high frequency layout:

■

■

Include 6.8µF and 0.1µF ceramic capacitors for power supply decoupling

■

■

Place the 6.8µF capacitor within 0.75 inches of the power pin

■

■

Place the 0.1µF capacitor within 0.1 inches of the power pin

■

■

Connection to the exposed pad is not required. Exposed pad can be connected to ground (GND).

■

■

Minimize all trace lengths to reduce series inductances

XR

18910