Electronic Components Datasheet Search |
|
SA828 Datasheet(PDF) 3 Page - Mitel Networks Corporation |
|
SA828 Datasheet(HTML) 3 Page - Mitel Networks Corporation |
3 / 14 page 3 SA828 Fig. 2 SA828 internal block diagram PULSE DELETION PULSE DELAY CIRCUIT RPHT RPHB PULSE DELETION PULSE DELAY CIRCUIT YPHT YPHB PULSE DELETION PULSE DELAY CIRCUIT BPHT BPHB RED PHASE YELLOW PHASE BLUE PHASE PHASING AND CONTROL LOGIC WAVEFORM ROM TRIP LATCH ADDRESS GENERATOR 24-BIT INITIALISATION REGISTER 24-BIT CONTROL REGISTER R0 R1 R2 R3 R4 BUS DEMULTIPLEXER BUS CONTROL CLOCK DIVIDER RST MOTEL INTERFACE SYSTEM BUS AD0-AD7 8 SET TRIP TRIP CS CLOCK ZPP O/Ps WSS FUNCTIONAL DESCRIPTION An asynchronous method of PWM generation is used with uniform or ‘double-edged’ regular sampling of the waveform stored in the internal ROM as illustrated in Fig. 3. The triangle carrier wave frequency is selectable up to 24kHz (assuming the maximum clock frequency of 12.5MHz is used), enabling ultrasonic operation for noise critical applications. With 12.5MHz clock, power frequency ranges of up to 4kHz are possible, with the actual output frequency resolved to 12-bit accuracy within the chosen range in order to give precise motor speed control and smooth frequency changing. The output phase sequence of the PWM outputs can also be changed to allow both forward and reverse motor operation. PWM output pulses can be ‘tailored’ to the inverter characteristics by defining the minimum allowable pulse width (the SA828 will delete all shorter pulses from the ‘pure’ PWM pulse train) and the pulse delay (underlap) time, without the need for external circuitry. This gives cost advantages in both component savings and in allowing the same PWM circuitry to be used for control of a number of different motor drive circuits simply by changing the microprocessor software. Power frequency amplitude control is also provided with an overmodulationoptiontoassistinrapidmotorbraking.Alternatively, braking may be implemented by setting the rotational speed to 0Hz. This is termed ‘DC injection braking’, in which the rotation of the motor is opposed by allowing DC to flow in the windings. AtripinputallowsthePWMoutputstobeshutdownimmediately, overriding the microprocessor control in the event of an emergency. The Waveform Sampling Synchronisation (WSS) output may be used in conjunction with the ZPP signals to provide feedback of the actual rotational speed from the rotor. This is of particular use in slip compensated systems. Other possible SA828 applications are as a 3-phase waveform generator as part of a switched-mode power supply (SMPS) or of an uninterruptible power supply (UPS). In such applications the high carrier frequency allows a very small switching transformer to be used. MICROPROCESSOR INTERFACE The SA828 interfaces to the controlling microprocessor by means of a multiplexed bus of the MOTEL format. This interface bus has the ability to adapt itself automatically to the format and timingofbothMOTorolaandIntELinterfacebuses(henceMOTEL). Internally, the detection circuitry latches the status of the DS/RD line when AS/ALE goes high. If the result is high then the Intel mode is used; if the result is low then the Motorola mode is used. This procedure is carried out each time that AS/ALE goes high. In practice this mode selection is transparent to the user. For bus connection and timing information refer to the description relevant to the microprocessor/controller being used. Industry standard microprocessors such as the 8085, 8088, etc. and microcontrollers such as the 8051, 8052 and 6805 are all compatible with the interface on the SA828. This interface consists of 8 data lines, AD0 - AD7 (write-only in this instance), which are multiplexed to carry both the address and data information, 3 bus control lines, labelled WR,RD and ALE in Intel mode and R/W, DS and AS in Motorola mode, and a Chip Select input, CS, which allows the SA828 to share the same bus as other microprocessor peripherals. It should be noted that all bus timings are derived from the microprocessor and are independent of the SA828 clock input. |
Similar Part No. - SA828 |
|
Similar Description - SA828 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |