TC1322_05 Datasheet, PDF (6/16 Pages) Microchip Technology – 12-Bit Digital-to-Analog Converter with Two-Wire Interface

TC1322
3.0 DETAILED DESCRIPTION
The TC1322 is a monolithic 10-bit digital-to-analog
converter that is designed to operate from a single sup-
ply that can range from 2.7V to 5.5V. The DAC consists
of a data register (DATA), a configuration register
(CONFIG), and a current output amplifier. The TC1322
uses an external reference, which also determines the
maximum output voltage.
The TC1322 uses a current steering DAC based on an
array of matched current sources. This current, along
with a precision resistor, converts the contents of the
Data register and V_REF into an output voltage, V_OUT
given by:
V_OUT = V_REF (DATA/4096)
3.1 Reference Input
The reference pin, V_REF, is a buffered high-impedance
input and because of this, the load regulation of the ref-
erence source needs only to be able to tolerate leakage
levels of current (less than 1μA). V_REF accepts a volt-
age range from 0 to (V_DD – 1.2V). Input capacitance is
typically 10pF.
3.2 Output Amplifier
The TC1322 DAC output is buffered with an internal
unity gain rail-to-rail input/output amplifier with a typical
slew rate of 0.8V/μsec. Maximum full scale transition
settling time is 10μsec to within ±1/2LSB when loaded
with 1kΩ in parallel with 100pF.
3.3 Standby Mode
The TC1322 allows the host to put it into a Low Power
(I_DD = 0.5μA, typical) Standby mode. In this mode, the
D/A conversion is halted. The SMBus port operates
normally. Standby mode is enabled by setting the
SHDN bit in the CONFIG register. The table below
summarizes this operation.
TABLE 3-1: STANDBY MODE OPERATION
SHDN Bit
0
1
Operating Mode
Normal
Standby
3.4 SMBus Slave Address
The TC1322 is internally programmed to have a default
SMBus address value of 1001 000b. Seven other
addresses are available by custom order (contact fac-
tory). See Figure 3-1 for location of address bits in
SMBus protocol.
DS21388C-page 6
© 2005 Microchip Technology Inc.