MAAD-008866_15 Datasheet, PDF (7/9 Pages) M/A-COM Technology Solutions, Inc. – Parallel Control

MAAD-008866
75 Ω Digital Attenuator, 6-Bit, Serial / Parallel Control
31.5 dB, 0.005 - 1.0 GHz
Functionality
Modes of Operation: Serial, Direct Parallel, and Latched Parallel
Mode Truth Table
P/S
LE
Mode
1
X
Serial
0
Constant High
Direct Parallel
0
Pulsed
Latched Parallel
Rev.V2
Serial Mode
The serial control interface (SERIN, CLK, LE, SEROUT) is compatible with the SPI protocol. SPI mode is
activated when P/S is kept high. The 6-bit serial word must be loaded with MSB first. After shifting in the 6 bit
word, bringing LE high will set the attenuator to the desired state. While LE is high the CLK is masked to protect
the data while implementing the change . SEROUT is the SERIN delayed by 6 clock cycles.
When P/S is low, the serial control interface is disabled and the serial input register is loaded asynchronously with
parallel digital inputs.
Direct Parallel Mode
The parallel mode is enabled when P/S is set to low. In the direct parallel mode, the attenuator is controlled by the
parallel control inputs directly. The LE must be at logic high to control the attenuator in this mode.
Latched Parallel Mode
In the latched parallel mode, the parallel control inputs will be buffered by registers, and loaded to the outputs
when LE is high. The outputs shall not change states when LE is low.
Power-up States
The power-up (PUP) states will work in both serial and parallel modes, and initiate the attenuator according to the
PUP truth table. During power up, the digital inputs shall be held constant for at least 1 μs after V_DD reaches 90%
of final value. For serial mode, the PUP states will only work when LE is held low. The PUP state shall be locked
out after the first LE pulse.
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