AD7538 Analog Devices, AD7538 Datasheet - Page 9

• Manufacturer Part Number: AD7538
• Description: LC2MOS Microprocessor-Compatible 14-Bit DAC
• Manufacturer: Analog Devices

Specifications of AD7538

• Resolution (bits): 14bit
• Dac Update Rate: 667kSPS
• Dac Settling Time: 1.5µs
• Max Pos Supply (v): +15.75V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: Par

DAC SECTION
Figure 4 shows a simplified circuit diagram for the AD7538
DAC section. The three MSBs of the 14-bit data word are
decoded to drive the seven switches (A to G). The 11 LSBs
of the data word consist of an R-2R ladder operated in a
current steering configuration.
The R-2R ladder current is ⅛ of the total reference input
current. ⅞ current flows in the parallel ladder structure.
V
REF
G
2R
F
2R
Figure 4. Simplified Circuit Diagram for the AD7538 DAC Section
E
2R
D
2R
C
2R
B
Rev. B | Page 9 of 16
2R
A
2R
R
S10
Switch A to Switch G steer equally weighted currents between
I
Because the input resistance at V
by a voltage source or a current source of positive or negative
polarity.
OUT
2R
and AGND.
R
S9
2R
R
S0
2R
2R
R/4
R
I
AGND
OUT
REF
FB
is constant, it may be driven
AD7538