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PulseWidthModulator
AD9561
FEATURES
60 MHz Pulse Rate
8-Bit Resolution
Center, Left or Right Justify
Low Power: 700 mW typical
Minimum Pulse Width: <5 ns
Maximum PW: 100 % Full.scale
FUNCTIONAL
BLOCK DIAGRAM
AD9561
CLOCK
APPLICATIONS
Laser Printers
Digital Copiers
Color Copiers
OBS
RsET
PWM
OUT
CALIN
6-8ITL
DATA
CAL
OUT
A
OLE
GENERAL DESCRIPTION
The AD9561 is a second generation high speed, digitally
programmable pulse width modulator (PWM). Output pulse
width is proportional to an 8-bit DATA input value. Two
additional control inputs determine if the pulse is placed at the
beginning, middle or end of the clock period. Pulse width and
placement can be changed every clock cycle up to 60 MHz.
Pulse width modulation is a well proven method for controlling
gray scale and resolution enhancement in scanning laser print
engines. Modulating pulse width provides the most cost
effective method for continuous tone reproduction and resolution enhancement in low-to-moderate cost scanning electrophotographic systems.
The AD9561 uses precision analog circuits to control dot size
so that near-photographic quality images are practical without
the high fi'equency clock signals required by all digital approaches.
The AD9561 has improved features and performance over its
predecessor, the AD9560. An improved ramp topology enables
control of pulse width through 100% of the dot clock period as
opposed to 95% for the AD9560. This enables smooth transition across dot boundaries for line screen applications.
SEMIDEM
LEMfTEM
RElRACE
TE
Additionally, input data setup and hold time are symmetrical at
2 ns each, simplifying interface to the system bus.
Finally, chip design and pinout are optimized to decrease
sensitivity of analog circuits to digital coupling. (See layout
section for detailed recommendations for optimum results.)
Inputs are TTL or CMOS compatible, and outputs are CMOS
compatible. The AD956lJR is packaged in a 28-lead plastic
SOIC. It is rated over the commercial temperature range, O°C
to +70°C.
HIGHLIGHTS
1. 60 MHz native printer clock rate.
2. Single +5 V power supply.
3. On-chip Autocalibration.
4. Pulse placement flexibility.
5. High resolution: 256 pulse widths.
REV.O
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements
of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One TechnologyWay,
Tel: 617/329-4700
Fax: 617/326-8703
P.O. Box9106, Norwood, MA02062-9106,
U.S.A.
World Wide Web Site: http://www.analog.com
@ Analog Devices, Inc., 1996