XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 137

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

19.4 D/A specification
The D/A generates a voltage on node DAB_OUT that is proportional to the code RegDabIn in between the positive
reference voltage DAB_R_P and the negative reference voltage DAB_R_M. The voltage on DAB_R_P always has
to be larger than the voltage on DAB_R_M. The DAB is intended for very low frequency use. The specification is
given in Table 19-3.
The DAB is based on a resistive ladder. Capacitors larger than 100pF are allowed on the node DAB_OUT, but the
step response will increase proportionally.
19.5 Amplifier specification
The amplifier output stage is a single transistor follower that is able to drive large currents. This transistor is not
connected internally so that different circuit configurations are possible (see next section). In order to guarantee
correct functionality, the voltage on the output pins has to respect the specifications VR
in Table 19-4.
© Semtech 2006
sym
wda
tstep
OR
refp
refn
Rdab
sym
gain
GBW
φ
R
C
CMR
VR
VR
V
noise
I
PSRR
I
I
source
bias
off
m
off
L
L
AOM
AOP
1. Time to reach the final value within 5%, C
1. For all possible combinations of resistive load and capacitive load.
2. At DC.
gain bandwidth product
description
number of input bits
step response
D/A output range
DAB_R_P range
DAB_R_M range
impedance between
DAB_R_P and DAB_R_M
description
gain at DC
phase margin
resistive load
capacitive load
common mode input range
DAB_AOM voltage range
DAB_AOP voltage range
offset
integrated input noise
max source current
power supply rejection ratio
quiescent bias current
off current
Table 19-4. Amplifier specification.
DAB_R_M
VSS+2.3
VSS+0.2
VSS+2.3
Table 19-3. D/A specification.
VSS
VSS
min
min
100
300
60
60
10
L
on DAB_OUT smaller than 100pF.
19-3
4500
±10
typ
0.1
90
80
60
40
80
5
0.25
typ
1.6
8
DAB_AOP-0.2
100000
DAB_R_P
VBAT-2.3
VBAT
VBAT
max
100
VBAT
10
max
1
1
1
unit
bits
ms
V
V
Mohm
unit
dB
Hz
°
Ω
nF
V
V
V
mV
µVrm
s
mA
dB
µA
µA
AOP
Note
1
1
1
1
1
2
and VR
note
1
XE8805/05A
AOM
www.semtech.com
as indicated