XTR108EA-2K5 BURR-BROWN [Burr-Brown Corporation], XTR108EA-2K5 Datasheet - Page 25

• Manufacturer Part Number: XTR108EA-2K5
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

VOLTAGE OUTPUT MODE USING SIMPLE
CURRENT PUMP
In order for the voltage output mode of the XTR108 to
operate properly, a negative voltage needs to be applied to
the I
a negative supply a charge pump is an easy way to generate
this voltage. Figure 14 shows a simple and inexpensive way
FIGURE 14. Voltage Output Mode Using Simple Current Pump.
FIGURE 15. Output Waveform of Simple Current Pump.
XTR108
SBOS187C
RTD
RET
pin (–200mV < I
R
CM
R
Z1
R
Z2
R
Z3
OPA OUT
R
Z4
RET
R
Z5
V/I-0
V/I-1
V/I-2
V/I-3
V/I-4
V/I-5
< –25mV). For systems without
50mV
5.0V
1
2
OPA –IN
OPA +IN
DAC
DAC
I
I
REF
LIN
PGA
C
FILT
0.01 F
www.ti.com
Zero
DAC
Linearization
Circuit
CS1
R
15.8k
LIN
to build this charge pump using two resistors, two capaci-
tors, and two diodes (in an SOT package). The charge pump
uses the clock signal from the XTR108 SCLK pin to operate;
consequently, the XTR108 must be in continuous EEPROM
read mode (register 4, bit 0). Figure 15 shows the typical
output of this circuit (–50mV dc).
Control Circuits
CS2
SPI and
R
SDIO SCLK
12.1k
SET
V
OUT
V
OUT
OSC
200mV < VOA+ < 25mV
30k
I
IN
2.5k
330pF
D
XTR108
SCLK
Charge
Pump
Output
SUB
BAV99
Sub-Regulator
51
Amplifier
Current
Driver
Output
0mV
Reference
Voltage
XTR108
1nF
Q1
36.5k
I
RET
V
V
I
I
Q1
O
REF
REF
Gate
S
= 0mA
V
IN
OUT
OUT
+5V
= 50mV
25