max5841 Maxim Integrated Products, Inc., max5841 Datasheet - Page 8

• Manufacturer Part Number: max5841
• Description: Max5841 Quad, 10-bit, Low-power, 2-wire, Serial Voltage-output Dac
• Manufacturer: Maxim Integrated Products, Inc.

Quad, 10-Bit, Low-Power, 2-Wire, Serial
Voltage-Output DAC
The MAX5841 is a quad, 10-bit, voltage-output DAC
with an I
device consists of a serial interface, power-down cir-
cuitry, four input and DAC registers, four 10-bit resistor
string DACs, four unity-gain output buffers, and output
resistor networks. The serial interface decodes the
address and control bits, routing the data to the proper
input or DAC register. Data can be directly written to
the DAC register, immediately updating the device out-
put, or can be written to the input register without
changing the DAC output. Both registers retain data as
long as the device is powered.
The MAX5841 uses a segmented resistor string DAC
architecture, which saves power in the overall system
and guarantees output monotonicity. The MAX5841’s
input coding is straight binary, with the output voltage
given by the following equation:
where N = 10 (bits), and D = the decimal value of the
input code (0 to 1023).
The MAX5841 analog outputs are buffered by preci-
sion, unity-gain followers that slew 0.5V/µs. Each buffer
output swings rail-to-rail, and is capable of driving 5kΩ
in parallel with 200pF. The output settles to ±0.5LSB
within 4µs.
The MAX5841 features an internal POR circuit that ini-
tializes the device upon power-up. The DAC registers
8
_______________________________________________________________________________________
PIN
10
1
2
3
4
5
6
7
8
9
2
C/SMBus-compatible 2-wire interface. The
V
OUT
NAME
OUTA
OUTB
OUTC
OUTD
GND
ADD
SDA
SCL
V
REF
DD
_
Detailed Description
=
V
REF
2
Address Select. A logic high sets the address LSB to 1; a logic low sets the address LSB to zero.
Serial Clock Input
Power Supply
Ground
Bidirectional Serial Data Interface
Reference Input
DAC A Output
DAC B Output
DAC C Output
DAC D Output
N
×
( )
D
Power-On Reset
DAC Operation
Output Buffer
are set to zero scale and the device is powered down,
with the output buffers disabled and the outputs pulled
to GND through the 100kΩ termination resistor.
Following power-up, a wake-up command must be initi-
ated before any conversions are performed.
The MAX5841 has three software-controlled low-power
power-down modes. All three modes disable the output
buffers and disconnect the DAC resistor strings from
REF, reducing supply current draw to 1µA and the ref-
erence current draw to less than 1µA. In power-down
mode 0, the device output is high impedance. In
power-down mode 1, the device output is internally
pulled to GND by a 1kΩ termination resistor. In power-
down mode 2, the device output is internally pulled to
GND by a 100kΩ termination resistor. Table 1 shows
the power-down mode command words.
Upon wake-up, the DAC output is restored to its previ-
ous value. Data is retained in the input and DAC regis-
ters during power-down mode.
The MAX5841 features an I
2-wire interface consisting of a serial data line (SDA)
and a serial clock line (SCL). The MAX5841 is SMBus
compatible within the range of V
and SCL facilitate bidirectional communication between
the MAX5841 and the master at rates up to 400kHz.
Figure 1 shows the 2-wire interface timing diagram. The
MAX5841 is a transmit/receive slave-only device, rely-
ing upon a master to generate a clock signal. The mas-
ter (typically a microcontroller) initiates data transfer on
the bus and generates SCL to permit that transfer.
A master device communicates to the MAX5841 by
transmitting the proper address followed by command
and/or data words. Each transmit sequence is framed-
FUNCTION
Power-Down Modes
Pin Description
2
C/SMBus-compatible
DD
Digital Interface
= 2.7V to 3.6V. SDA