max5812peut-t Maxim Integrated Products, Inc., max5812peut-t Datasheet - Page 7

• Manufacturer Part Number: max5812peut-t
• Description: Max5812 12-bit Low-power, 2-wire, Serial Voltage-output Dac
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5812 is a 12-bit, voltage-output DAC with an
I
sists of a serial interface, power-down circuitry, input
and DAC registers, a 12-bit resistor string DAC, unity-
gain output buffer, and output resistor network. The seri-
al interface decodes the address and control bits,
routing the data to either the input or DAC register. Data
can be directly written to the DAC register immediately
updating the device output, 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 MAX5812 uses a segmented resistor string DAC
architecture, which saves power in the overall system
and guarantees output monotonicity. The MAX5812’s
input coding is straight binary with the output voltage
given by the following equation:
where N = 12(bits), and D = the decimal value of the
input code (0 to 4095).
The MAX5812 analog output is buffered by a precision
unity-gain follower that slews 0.5V/µs. The buffer output
Table 1. Power-Down Command Bits
2
C/SMBus-compatible 2-wire interface. The device con-
PIN
PD1
COMMAND BITS
1
2
3
4
5
6
POWER-DOWN
0
0
1
1
NAME
GND
ADD
OUT
SDA
V
SCL
_______________________________________________________________________________________
PD0
V
DD
0
1
0
1
OUT
Detailed Description
=
V
REF
Power Supply and DAC Reference Input
Ground
Bidirectional Serial Data I/O
Serial Clock Line
Address Select. A logic high sets the address LSB to 1; a logic low sets the address LSB to 0.
Analog Output
Power-up device. DAC output restored to previous value.
Power-down mode 0. Powers down device with output floating.
Power-down mode 1. Powers down device with output terminated with 1kΩ to GND.
Power-down mode 2. Powers down device with output terminated with 100kΩ to GND.
2
N
×
( )
D
DAC Operation
Output Buffer
12-Bit Low-Power, 2-Wire, Serial
swings rail-to-rail and is capable of driving 5kΩ in paral-
lel with 200pF. The output settles to ±0.5LSB within 4µs.
The MAX5812 features an internal power-on-reset
(POR) circuit that initializes the device upon power-up.
The DAC registers are set to zero-scale and the device
is powered down with the output buffer disabled and
the output pulled to GND through the 100kΩ termina-
tion resistor. Following power-up, a wake-up command
must be initiated before conversions are performed.
The MAX5812 has three software-controlled, low-
power, power-down modes. All three modes disable
the output buffer and disconnect the DAC resistor
string from V
300nA. 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 resis-
tor. 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 MAX5812 features an I
2-wire interface consisting of a serial data line (SDA)
MODE/FUNCTION
FUNCTION
Voltage-Output DAC
DD
, reducing supply current draw to
Power-Down Modes
Pin Description
2
C/SMBus-compatible
Digital Interface
Power-On Reset
7