Product category: Analogue and Mixed Signal ICs
News Release from: National Semiconductor | Subject: LM8322 and LM8333
Edited by the Electronicstalk Editorial Team on 11 July 2007
Mobile I/O companions offload processor
tasks
Devices offer easy way to expand system functionality in portable products such as personal digital assistants, media players, instrumentation, medical equipment and mobile handsets.
A new mobile input/output (I/O) companion family from National Semiconductor offers designers an easy way to expand system functionality in portable products such as personal digital assistants, media players, instrumentation, medical equipment and mobile handsets Portable device manufacturers continue to differentiate their products through added features such as custom keyboards or special lighting
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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National's LM8322 and LM8333 mobile I/O companions allow designers to repartition their systems by offloading tasks from the processor and adding features through a reconfigurable set of simple commands.
The flexible, modular single chips enable use of the same host processor and companion across multiple product versions.
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The LM8322 and LM8333 off-the-shelf integrated circuits include embedded key-scan functions, I/O expansion and light-emitting diode (LED) control capabilities.
Communication from the mobile I/O companion with the host processor is performed via a standard I2C compatible bus and interrupt signal that require only three pins, giving designers more options in placing the host processor on the board.
A set of complex commands and scripts for PWM signal generation allows the host to quickly configure the mobile I/O companion's resources or trigger execution of commands.
Using the simple command set, the host processor can configure the LM8322 and LM8333 through an I2C compatible Access.bus interface in slave mode up to 400kHz.
The fully tested and qualified companion chips dramatically reduce system design time and maintain accurate performance over the industrial temperature range of -40 to +85C.
The LM8322 supports keypad matrices up to 104 keys, while the LM8333 supports up to 72 keys.
Both have eight special-function keys that take priority in the key rolling sequence.
The on-chip clock, power-on-reset and on-chip oscillator require minimal external circuitry to support the mobile I/O companion's operation.
By offloading the keyboard scanning feature to the companion, the host processor can enter sleep mode and reduce system power consumption.
When there is no activity on the host bus or keypad, the companion automatically enters standby mode, typically consuming 18uW.
The LM8322 has 1.62 to 1.98V single-supply operation and up to 16 pins that can be configured as general-purpose I/O expansion for controlling additional peripherals.
Its three independent, host-programmable PWM outputs can be used to generate more complex signals for adjusting an LED's brightness or other sophisticated lighting effects.
Available now, National's LM8322 in a 36-pin micro array package is priced at US $2.65 each.
The LM8333, available in both 32-pin LLP and 49-pin micro array packages, is priced at US $1.95 and $2.05 each.
All prices are in 1000-unit quantities.
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