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4-6
Theory of Operation
when the screen appears) is completed, because the program must be processed in
the SDRAM after transferring the program content from the Flash PROM into the
SDRAM.
NVRAM
This memory chip is powered from V
CCO
in the RTC. When the main power is off,
the NVRAM is powered by the lithium battery, when it is on, it is powered from V
CC
.
The #CS1 signals are also controlled by the RTC. When the main power is turned
off, the RTC sets the chip select "high" to place the SRAM in power-down mode to
prevent any accidental overwriting. Stored panel setups (Setup1 - 4), the
instruments last panel setup and trace memories M1-M4 are stored in the NVRAM.
RTC
The DS1689 real time clock has several functions:
•
Keeps the time-of-day and current-date information while power is off.
•
Generates the 32KHz clock for SDRAM refreshing.
•
Generates a 128Hz periodic interrupt signal to force bus accessing from
the processor and allow periodic updating of the time display.
•
Provides a unique ID that identifies the origination of scope ID.
•
Feeds the power and the chip select signal to the NVRAM.
The RTC chip generates timing clocks necessary for time keeping and other circuits
using a 32.768KHz crystal. A few discrete components around the RTC leave it
powered by the lithium battery when the system is turned off. When the system is
turned on this circuit charges the battery. Accesses from the processor are done
through bus separation circuit, since addresses and data are multiplexed. A unique
ID is written into the RTC by the RTC manufacturer, since every chip must have a
different value stored in it.
Содержание Waverunner2 LT262 Series
Страница 1: ...LTXXX2 SM E LeCroy Waverunner2 Series Service Manual Version D December 2003 ...
Страница 30: ...4 12 Theory of Operation Block diagram 1 HAM631 ...
Страница 55: ...Rev D Performance Verification 5 19 ...
Страница 62: ...5 26 Performance Verification Rev D Set Global BWL 200 MHz Set Timebase 5 nsec div ...
Страница 80: ...5 44 Performance Verification Rev D a Pulse Width 10 nsec b Pulse Width 10 nsec ...
Страница 84: ...5 48 Performance Verification Rev D ...
Страница 86: ...Rev D 2 of 12 This page intentionally left blank ...
Страница 96: ...Rev D 12 of 12 LT584 LT374 372 LT354 LT264 262 Test Record This page intentionally left blank ...
Страница 114: ...6 18 Maintenance ...
Страница 126: ...7 12 Mechanical Parts Removal F2 ...
Страница 154: ...Mechanical Part Removal 7 21 ...