ML2330
CS
t
t
CSH
CSS
S
CLK
t
DS
t
DH
D
IN
t
DO
D
OUT
Figure 2. Detail Interface Timing
FUNCTIONAL DESCRIPTION
SERIAL INTERFACE
The 4-bit address/control code configures the DAC as
shown in Table 1.
The ML2330 communicates with microprocessors through
a synchronous, full-duplex, 3-wire interface (figure 1A &
B). At power on, the control registers are cleared and both
DACs have high impedance outputs. Data timing shown
in Figure 1C is sent MSB-first and can be transmitted in
one 4-bit and one 8-bit packet or in one 12-bit word. If a
16-bit control word is used, the first four bits are ignored.
A1
0
A0
0
Function
No operation
0
1
Select control bits and DAC A
Select control bits and DAC B
Select control bits and both DACs
1
0
The serial clock (S ) synchronizes the data transfer. Data
CLK
1
1
is transmitted and received simultaneously. Figure 2 shows
detailed serial interface timing. Note that the clock should
Table 1.1 Address Selection
be low between updates. D
impedance state if the clock idles or CS is high.
does not go into a high
OUT
P1
0
P0
Function
Serial data is clocked into the data registers in MSB-first
format, with the address and configuration information
preceding the actual DAC data. Data is sampled on the
0
1
0
1
Normal
0
Power down DAC A
Power down DAC B
Power down entire chip
S
’s rising edge while CS is low. Data at D
is
CLK
OUT
clocked out 12.5 clock cycles later, on the S ’s falling
CLK
1
edge.
1
Chip Select (CS) must be low to enable the read or write
operation. If CS is high, the interface is disabled and D
OUT
Table 1.2 Power Down Selection
remains unchanged. CS must go low at least 10ns before
the first clock pulse to properly clock in the first bit. With
CS low, data is clocked into the ML2330’s internal shift
DAC OPERATION
The DACs are implemented using an array of equal
current sources that are decoded linearly for the four most
significant bits to improve differential linearity and to
reduce output glitch around major carries. A voltage
difference between on-board bandgap reference voltage
and GND is converted to a reference current using an
internal resistor to set up the appropriate current level in
the DACs. The DACs output current is then converted to a
voltage output by an output buffer and a resistive network.
The matching among the on-chip resistors preserves the
gain accuracy between these conversions.
register on the rising edge of the external serial clock. S
can be driven at rates up to 10MHz.
CLK
SERIAL INPUT DATA FORMAT AND
CONFIGURATION CODES
The 12-bit serial input format shown in Figure 3 comprises
two DAC address bits (A1, A0), two power down control
bits (P1, P0) and eight bits of data (D7 . . . D0).
DOUT
DIN
A1 A0 P1 D7 . . . D0
Figure 3. Serial Input Format
5
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
