PE43502
Product Specification
Programming Options
Parallel/Serial Selection
Either a parallel or serial interface can be used to
control the PE43502. The
P̅
/S bit provides this
selection, with
P̅
/S=LOW selecting the parallel
interface and
P̅
/S=HIGH selecting the serial
interface.
Parallel Mode Interface
The parallel interface consists of five CMOS-
compatible control lines that select the desired
attenuation state, as shown in
Table 7.
The parallel interface timing requirements are
defined by
Fig. 16
(Parallel Interface Timing
Diagram),
Table 11
(Parallel Interface AC
Characteristics), and switching speed (Table
1).
For
latched-parallel
programming the Latch Enable
(LE) should be held LOW while changing attenuation
state control values, then pulse LE HIGH to LOW
(per
Fig. 16)
to latch new attenuation state into
device.
For
direct
parallel programming, the Latch Enable
(LE) line should be pulled HIGH. Changing
attenuation state control values will change device
state to new attenuation. Direct Mode is ideal for
manual control of the device (using hardwire,
switches, or jumpers).
as data is entered. The LE input should then be
toggled HIGH and brought LOW again, latching the
new data into the DSA. Attenuation Word truth table
is listed in
Table 8.
A programming example of the
serial register is illustrated in
Table 9.
The serial
timing diagram is illustrated in
Fig. 15.
It is required
that all parallel pins be grounded when the DSA is
used in serial mode.
Power-up Control Settings
The PE43502 will always initialize to the maximum
attenuation setting (15.5 dB) on power-up for both
the serial and latched-parallel modes of operation
and will remain in this setting until the user latches in
the next programming word. In direct-parallel mode,
the DSA can be preset to any state within the 15.5
dB range by pre-setting the parallel control pins prior
to power-up. In this mode, there is a 400-µs delay
between the time the DSA is powered-up to the time
the desired state is set. During this power-up delay,
the device attenuates to the maximum attenuation
setting (15.5 dB) before defaulting to the user
defined state. If the control pins are left floating in
this mode during power-up, the device will default to
the minimum attenuation setting (insertion loss
state).
Dynamic operation between serial and parallel
programming modes is possible.
If the DSA powers up in serial mode (P̅/S = HIGH),
all the parallel control inputs DI[5:1] must be set to
logic low. Prior to toggling to parallel mode, the DSA
must
be programmed serially to ensure D[7] is set to
logic low.
If the DSA powers up in either latched or direct-
parallel mode, all parallel pins DI[5:1] must be set to
logic low prior to toggling to serial mode (P̅/S
= HIGH), and
held
low until the DSA has been
programmed serially to ensure bit D[7] is set to logic
low.
The sequencing is only required once on power-
up. Once completed, the DSA may be toggled
between serial and parallel programming modes at
will.
Serial Interface
The serial interface is a 8-bit serial-in, parallel-out
shift register buffered by a transparent latch. The 8-
bits make up the Attenuation Word that controls the
DSA.
Fig. 15
illustrates a example timing diagram for
programming a state.
The serial-interface is controlled using three CMOS-
compatible signals: Serial-In (SI), Clock (CLK), and
Latch Enable (LE). The SI and CLK inputs allow
data to be serially entered into the shift register.
Serial data is clocked in LSB first.
The shift register must be loaded while LE is held
LOW to prevent the attenuator value from changing
©2008-2009 Peregrine Semiconductor Corp. All rights reserved.
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Document No. 70-0247-06
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UltraCMOS™ RFIC Solutions
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