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W3EG6432S335D4I Datasheet(PDF) 9 Page - White Electronic Designs Corporation |
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W3EG6432S335D4I Datasheet(HTML) 9 Page - White Electronic Designs Corporation |
9 / 12 page 9 White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com White Electronic Designs W3EG6432S-D4 December 2004 Rev. 6 PRELIMINARY Notes 1. All voltages referenced to VSS. 2. Tests for AC timing, IDD, and electrical AC and DC characteristics may be conducted at nominal reference/supply voltage levels, but the related specifications and device operation are guaranteed for the full voltage range specified. 3. Outputs measured with equivalent load: Output Output (V (VOUT OUT ) Reference Reference Point Point 50Ω 50Ω VTT TT 30pF 30pF 4. AC timing and IDD tests may use a VIL-to-VIH swing of up to 1.5V in the test environment, but input timing is still referenced to VREF (or to the crossing point for CK/CK#), and parameter specifications are guaranteed for the specified AC input levels under normal use conditions. The mini-mum slew rate for the input signals used to test the device is 1V/ns in the range between VIL (ACV) and VIH (AC). 5. The AC and DC input level specifications are as defined in the SSTL_2 Standard (i.e., the receiver will effectively switch as a result of the signal crossing the AC input level, and will remain in that state as long as the signal does not ring back above [below] the DC input LOW [HIGH] level). 6. VREF is expected to equal VCCQ/2 of the transmitting device and to track variations in the DC level of the same. Peak-to-peak noise (non-common mode) on VREF may not exceed ±2 percent of the DC value. Thus, from VCCQ/2, VREF is allowed ±25mV for DC error and an additional ±25mV for AC noise. This measurement is to be taken at the nearest VREF by-pass capacitor. 7. VTT is not applied directly to the device. VTT is a system supply for signal termination resistors, is expected to be set equal to VREF and must track variations in the DC level of VREF. 8. IDD is dependent on output loading and cycle rates. Specified values are obtained with mini-mum cycle time at CL = 2 for 262, 263, and 202, CL = 2.5 for 335 and 265 with the outputs open. 9. Enables on-chip refresh and address counters. 10. IDD specifications are tested after the device is properly initialized, and is averaged at the defined cycle rate. 11. This parameter is sampled. VCC = +2.5V ±0.2V, VCCQ = +2.5V ±0.2V, VREF = VSS, f = 100 MHz, TA = 25°C, VOUT (DC) = VCCQ/2, VOUT (peak to peak) = 0.2V. DM input is grouped with I/O pins, reflecting the fact that they are matched in loading. 12. For slew rates < 1 V/ns and ≥ to 0.5 Vns. If the slew rate is < 0.5V/ns, timing must be derated: tIS has an additional 50ps per each 100 mV/ns reduction in slew rate from 500 mV/ns, while tIH is unaffected. If the slew rate exceeds 4.5 V/ns, functionality is uncertain. For 335, slew rates must be 0.5 V/ns. 13. The CK/CK# input reference level (for timing referenced to CK/CK#) is the point at which CK and CK# cross; the input reference level for signals other than CK/CK# is VREF. 14. Inputs are not recognized as valid until VREF stabilizes. Exception: during the period before VREF stabilizes, CKE < 0.3 x VCCQ is recognized as LOW. 15. The output timing reference level, as measured at the timing reference point indicated in Note 3, is VTT. 16. tHZ and tLZ transitions occur in the same access time windows as valid data transitions. These parameters are not referenced to a specific voltage level, but specify when the device output is no longer driving (HZ) or begins driving (LZ). 17. The intent of the “Don’t Care” state after completion of the postamble is that the DQS-driven signal should either be HIGH, LOW, or High-Z and that any signal transition within the input switching region must follow valid input requirements. If DQS transitions HIGH, above DC VIH (MIN) then it must not transition LOW, below DC VIH, prior to tDQSH (MIN). 18. This is not a device limit. The device will operate with a negative value, but system performance could be degraded due to bus turnaround. 19. It is recommended that DQS be valid (HIGH or LOW) on or before the WRITE command. The case shown (DQS going from High-Z to logic LOW) applies when no WRITEs were previously in progress on the bus. If a previous WRITE was in progress, DQS could be HIGH during this time, depending on tDQSS. 20. MIN (tRC or tRFC) for IDD measurements is the smallest multiple of tCK that meets the minimum absolute value for the respective parameter. tRAS (MAX) for IDD measurements is the largest multiple of tCK that meets the maximum absolute value for tRAS. 21. The refresh period is 64ms. This equates to an average refresh rate of 7.8125µs. However, an AUTO REFRESH command must be asserted at least once every 70.3µs; burst refreshing or posting by the DRAM controller greater than eight refresh cycles is not allowed. 22. The valid data window is derived by achieving other specifications: tHP (tCK/2), tDQSQ, and tQH (tQH = tHP - tQHS). The data valid window derates directly porportional with the clock duty cycle and a practical data valid window can be derived. The clock is allowed a maximum duty cycle variation of 45/55, beyond which functionality is uncertain. Figure 7, Derating Data Valid Window (tQH - tDQSQ), shows the derating curves for duty cycles ranging between 50/50 and 45/55. 23. Each byte lane has a corresponding DQS. 24. This limit is actually a nominal value and does not result in a fail value. CKE is HIGH during REFRESH command period (tRFC [MIN]) else CKE is LOW (i.e., during standby). 25. To maintain a valid level, the transitioning edge of the input must: a. Sustain a constant slew rate from the current AC level through to the target AC level, VIL (AC) or VIH (AC). b. Reach at least the target AC level. c. After the AC target level is reached, continue to maintain at least the target DC level, VIL (DC) or VIH (DC). 26. JEDEC specifies CK and CK# input slew rate must be ≥ 1V/ns (2V/ns differentially). 27. DQ and DM input slew rates must not deviate from DQS by more than 10 percent. If the DQ/ DM/DQS slew rate is less than 0.5 V/ns, timing must be derated: 50ps must be added to tDS and tDH for each 100mv/ns reduction in slew rate. If slew rate exceeds 4 V/ns, functionality is uncertain. For 335, slew rates must be ≥ 0.5 V/ns. 28. VCC must not vary more than 4 percent if CKE is not active while any device bank is active. 29. The clock is allowed up to ±150ps of jitter. Each timing parameter is allowed to vary by the same amount. 30. tHP min is the lesser of tCL minimum and tCH minimum actually applied to the device CK and CK# inputs, collectively during device bank active. 31. READs and WRITEs with auto precharge are not allowed to be issued until tRAS (MIN) can be satisfied prior to the internal precharge command being issued. 32. Any positive glitch in the nominal voltage must be less than 1/3 of the clock and not more than +400mV or 2.9V maximum, whichever is less. Any negative glitch must be less than 1/3 of the clock cycle and not exceed either -300mV or 2.2V mini-mum, whichever is more positive. |
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