Rainbow Electronics MAX5157 - Manual (Page 16)

MAX5156/MAX5157
Low-Power, Dual, 12-Bit Voltage-Output DACs
with Configurable Outputs
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Digitally Programmable Current Source
Figure 15 depicts a digitally programmable, unidirec-
tional current source that can be used in industrial con-
trol applications. The output current is:
I OUT = (V REF / R) (NB / 4096)
where NB is the DAC code and R is the sense resistor.
Power-Supply Considerations
On power-up, the input and DAC registers clear (resets
to zero code). For rated performance, V
REF_ should be
at least 1.4V below V DD . Bypass the power supply with
a 4.7µF capacitor in parallel with a 0.1µF capacitor to
GND. Minimize lead lengths to reduce lead inductance.
Grounding and Layout Considerations
Digital and AC transient signals on AGND can create
noise at the output. Connect AGND to the highest quali-
ty 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 recommend-
ed. If noise becomes an issue, shielding may be
required.
MAX5156
MAX5157
DAC_
REF_
2N3904
R
V L
I
OUT
AGND
FB_
OUT_
+5V/+3V
V
DD
DGND
Figure 15. Digitally Programmable Current Source
___________________Chip Information
TRANSISTOR COUNT: 3053
SUBSTRATE CONNECTED TO AGND
__________________Pin Configuration _Ordering Information (continued)
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
AGND V DD
OUTB
FBB
REFB
PDL
UPO
DOUT
DGND
TOP VIEW
MAX5156
MAX5157
DIP/QSOP
OUTA
FBA
CS
REFA
CL
DIN
SCLK
* Contact factory for availability.
INL
(LSB)
PIN-PACKAGE TEMP. RANGE PART
±1
±1
±1/2
±1
±1/2
±2
±2
16 CERDIP* -55°C to +125°C MAX5156BMJE
16 QSOP -40°C to +85°C MAX5156BEEE
16 QSOP -40°C to +85°C MAX5156AEEE
16 Plastic DIP -40°C to +85°C MAX5156BEPE
16 Plastic DIP -40°C to +85°C MAX5156AEPE
±1
±2
±1
±2
±1
16 QSOP 0°C to +70°C MAX5157BCEE
±2 16 Plastic DIP 0°C to +70°C MAX5157BCPE
±1 16 QSOP 0°C to +70°C MAX5157ACEE
16 CERDIP* -55°C to +125°C MAX5157BMJE
16 QSOP -40°C to +85°C MAX5157BEEE
16 QSOP -40°C to +85°C MAX5157AEEE
16 Plastic DIP -40°C to +85°C MAX5157BEPE
16 Plastic DIP -40°C to +85°C MAX5157AEPE
16 Plastic DIP 0°C to +70°C MAX5157 ACPE