XE8805AMI028LF Semtech, XE8805AMI028LF Datasheet - Page 132

• Manufacturer Part Number: XE8805AMI028LF
• Description: IC DAS 16BIT FLASH 8K MTP 64LQFP
• Manufacturer: Semtech

Specifications of XE8805AMI028LF

• Applications: Sensing Machine
• Core Processor: RISC
• Program Memory Type: FLASH (22 kB)
• Controller Series: XE8000
• Ram Size: 512 x 8
• Interface: UART, USRT
• Number Of I /o: 24
• Voltage - Supply: 2.4 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Supply Voltage Range: 2.4V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LQFP
• No. Of Pins: 64
• For Use With: XE8000MP - PROG BOARD AND PROSTART2 CARD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The resistor value R
maximal loop current. The resistor R
Allowing for an error of 0.1% gives R
The resistor R
Using the large bandwidth of the amplifier is recommended since this increases the rejection of supply current
variations of the other components in the loop. A bypass capacitor between VBAT and VSS will also reduce the
high frequency current variations. Values will depend on the voltage regulator used. The software in the XE8805
should keep the current supply of the circuit as stable as possible. This means that the clock frequency should kept
constant, peripherals should not be switched on and off, the current in the sensor is kept constant, the processor
should not use the halt or sleep modes, etc.
The resistor R
see section 18.4.3.2) equal to the full scale signal current of 16mA:
The resistor R
© Semtech 2006
Sensor
R
R
offset
f
1
≤
offset
offset
f1
≤
(
VBAT
can then be calculated to set the full scale D/A code range (depends on the PWM modulation m,
XE88xx
(
VBAT
may be omitted but it will reduce the useful code range of the D/A.
can be calculated in order to obtain a 4mA current while the D/A code is 0:
sense
R
2
−
sense
m
VSS
−
⋅
is generally chosen between 50Ω and 150Ω resulting in a 1V to 3V voltage drop at
R
VSS
c
o
n
o
t
r
l
⋅
sense
4
)
mA
⋅
Figure 18-4. 2-wire 4-20mA loop with first order filter
)
2 (
⋅
⋅
16
R
m
D
mA
f
f2
−
2
=R
f2
VBAT
) 1
VSS
is then chosen much larger depending on the current error requirement.
sense
⋅
A
R
f
/0.001.
2
amp
18-11
DAS_AI_M
DAS_OUT
DAS_AI_P
DAS_AO
VBAT
C
f
R
offset
V
R
f
f1
VSS
R
f2
regulator
Voltage
R
lim1
R
lim2
R
XE8805/05A
sense
4-20mA
4-20mA
V
V
EXT
EXT
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