MAX5155AEEE-T Maxim Integrated, MAX5155AEEE-T Datasheet - Page 15

• Manufacturer Part Number: MAX5155AEEE-T
• Description: Digital to Analog Converters - DAC
• Manufacturer: Maxim Integrated

Specifications of MAX5155AEEE-T

• Number Of Converters: 2
• Number Of Dac Outputs: 2
• Resolution: 12 bit
• Interface Type: QSPI, SPI, Serial (3-Wire, Microwire)
• Settling Time: 15 us
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QSOP-16
• Minimum Operating Temperature: - 40 C
• Output Type: Voltage
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 2.7 V
• Voltage Reference: External

it trips the comparator. The microprocessor (µP) stores
this “high” calibration value. Repeat the process with a
dim light (off) to obtain the dark current calibration.
The µP then programs the DAC to set an output voltage
at the midpoint of the two calibrated values.
Applications include tachometers, motion sensing,
automatic readers, and liquid clarity analysis.
The two DACs can be used to control the offset and
gain for curve-fitting nonlinear functions, such as trans-
ducer linearization or analog compression/expansion
applications. The input signal is used as the reference
for the gain-adjust DAC, whose output is summed with
the output from the offset-adjust DAC. The relative
weight of each DAC output is adjusted by R1, R2, R3,
and R4 (Figure 14).
Figure 14. Digital Control of Gain and Offset
V
V
REF
IN
Low-Power, Dual, 12-Bit Voltage-Output DACs
SCLK
REFA
REFB
DIN
CS
Digital Control of Gain and Offset
REGISTER
SHIFT
MAX5154
MAX5155
______________________________________________________________________________________
INPUT
REG A
INPUT
REG B
REG A
REG B
DAC
DAC
V
DD
AGND
DACA
DACB
DGND
On power-up, the input and DAC registers clear (set to
zero code). For rated performance, V
least 1.4V below V
4.7µF capacitor in parallel with a 0.1µF capacitor to
AGND. Minimize lead lengths to reduce lead inductance.
Digital and AC transient signals on AGND can create
noise at the output. Connect AGND to the highest quality
ground available. Use proper grounding techniques,
such as a multilayer board with a low-inductance ground
plane. Carefully lay out the traces between channels to
reduce AC cross-coupling and crosstalk. Wire-wrapped
boards and sockets are not recommended. If noise
becomes an issue, shielding may be required.
R
R
R
R
with Serial Interface
OUTA
OUTB
OSB
OSA
Grounding and Layout Considerations
V
OUT
NA IS THE NUMERIC VALUE OF THE INPUT CODE FOR DACA.
NB IS THE NUMERIC VALUE OF THE INPUT CODE FOR DACB.
R1
R3
=
=
[ ]
[
(
GAIN
V
Power-Supply Considerations
IN
DD
2NA
4096
– OFFSET
. Bypass the power supply with a
R2
[
)(
R1+R2
R2
]
)(
R4
1+
R4
R3
) (
] [
REF_
V
V
OUT
REF
4096
should be at
2NB
)( )
R4
R3
]
15