|
|
Part: 54HSCT630FC
Category:
Logic
-> Memory Interface
-> Controller/Driver->Error Detect/Correct
Description: Radiation Hard 16-bit Parallel Error Detection & Correction
Company: Dynex Semiconductor
Datasheet: Download 54HSCT630FC datasheet File size : 218 kB
Request For quote: Find where to buy 54HSCT630FC
Datasheet text preview:
54HSC/T630 54HSC/T630
Radiation hard 16-Bit ParallelError Detection & Correction
Replaces January 2000 version, DS3595-5.0 DS3595-5.1 July 2002
The 54HSC/T630 is a 16-bit parallel Error Detection and Correction circuit. It uses a modified Hamming code to generate a 6-bit check word from each 16-bit data word. The check word is stored with the data word during a memory write cycle. During a memory read cycle a 22-bit word is taken from memory and checked for errors. Single bit errors in data words are flagged and corrected. Single bit errors in check words are flagged but not corrected. The position of the incorrect bit is pinpointed, in both cases, by the 6-bit error syndrome code which is output during the error correction cycle. Two bit errors are flagged but not corrected. Any combination of two bit errors occurring within the 22-bit word read from memory, (ie two errors in the 16-bit data word, two bits in the 16-bit check word or one error in each) will be correctly identified. The gross errors of all bits, low or high, will be detected. The control signals S1 and S0 select the function to be performed by the EDAC They control the generation of check words and the latching and correction of data (see table 1) When errors are detected, flags are placed on outputs SEF and DEF (see table 2).
Figure 1: Block Diagram
FEATURES
s Radiation Hard: Dose Rate Upset Exceeding 3x1010 Rad(Si)/sec Total Dose for Functionality Upto 1x106 Rad(Si) s High SEU Immunity, Latch Up Free s CMOS-SOS Technology s All Inputs and Outputs Fully TTL Compatible (54HST630) or CMOS Compatible (54HSC630) s Low Power s Detects and Corrects Single-Bit Errors s Detects and Flags Dual-Bit Errors s High Speed: Write Cycle - Generates Checkword In 40ns Typical Read Cycle - Flags Errors In 20ns Typical
1/10
54HSC/T630
Control Cycle WRITE READ READ READ S1 Low Low High High S0 Low High High Low EDAC Function Generates Checkword Read Data BCheckword Latch & Flag Error Correct Data Word & Generate Syndrome Bits Data UO Input Data Input Data Latch Data Output Corrected Data Checkword Output Checkword Input Checkword Latch Checkword Output Syndrome Bits Error Flags SEF Low Low Enabled Enabled DEF Low Low Enabled Enabled
Table 1: Control Functions
Total Number of Errors 16-bit Data 0 1 0 1 2 0 6-bit Checkword 0 0 1 1 0 2 SEF Low High High High High High
Error Flags DEF Low Low Low High High High
Data Correction
Not Applicable Correctlon Correction Interrupt Interrupt Interrupt
Table 2: Error Functions
ERROR DETECTION & CORRECTION
During a memory write cycle, six check bits (CBO-CB5) are generated by eight-input parity generators using the data bits defined in Table 3. During a memory read cycle, the 6-bit checkword is retrieved along with the actual data. Error detection is accomplished as the 6-bit checkword and the 16-bit data word from memory are applied to internal parity generators/checkers. If the parity of all six groupings of data and check bits are correct, it is assumed that no error has occurred and both error flags will be low. It should be noted that the sense of two of the check bits, bits CBO and CB1, is inverted to ensure that the gross-error condition of all lows and all highs is detected. If the parity of one or more of the check groups is incorrect, an error has occurred and the proper error flag or flags will be set high. Any single error in the 16bit data word will change the sense of exactly three bits of the 6-bit checkword. Any single error in the 6bit checkword changes the sense of only that one bit. In either case, the single error flag will be set high while the dual error flag will remain low. Any two-bit error will change the sense of an even number of check bits. The two-bit error is not correctable since the parity tree can only identify singlebit errors. Both error flags are set high when any two-bit error is detected. Three or more simultaneous bit errors cause the EDAC to transmit that no error, a correctable error, or an uncorrectable error has occurred and hence produce erroneous results in all three cases. Error correction is accomplished by identifying the bad bit and inverting it. Identification of the erroneous bit is achieved by comparing the 16-bit word and 6-bit checkword from memory with the new checkword with one (checkword error) or three (data word error) inverted bits. As the corrected word is made available on the data word l/ O port, the checkword l/O port presents a 6-bit syndrome error code. This syndrome code can be used to identify the corrupted bit in memory (see Table 4. overleaf).
2/10
54HSC/T630
16-bit Data Word Checkword Bit CB0 CB1 CB2 CB3 CB4 CB5 0 X X X 1 X X X X X X 2 3 X X 4 X X X X X X X X X X X X X X 5 6 7 8 X X 9 X X X X X X X 10 X X X X X X X X X 11 12 13 X X X X X 14 15
The six check bits are partly bits derived from the matrix of data bits as indicated by 'X' for each bit.
Table 3: Check Word Generation
Syndrome Error Code CB0 CB1 CB2 CB3 CB4 CB5
Error Location
No DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 DB8 DB9 DB10 DB11 DB12 DB13 DB14 DB15 CB0 CB1 CB2 CB3 CB4 CB5 Error
L L H L H H
L H L L H H
H L L L H H
L L H H L H
L H L H L H
H L L H L H
H L H L L H
H H L L L H
L L H H H L
L H L H H L
L H H L H L
H L H L H L
H H L L H L
L H H H L L
H L H H L L
H H L H L L
L H H H H H
H L H H H H
H H L H H H
H H H L H H
H H H H L H
H H H H H L
H H H H H H
Table 4: Error Syndrome Codes
APPLICATIONS
Although many semiconductor memories have separate input and output pins, it is possible to design the error detection and correction function using a single EDAC. EDAC d a t a and check bit pins function as inputs or outputs dependent upon the state of control signals S0 and S1. It becomes necessary to use wired AND logic, with fairly complex timing system, to control the EDAC and data bus. This scheme becomes difficult to implement both in terms of b o a r d layout and timing. System performance is also adversely affected, See Figure 2. Optimised systems can be implemented using two EDAC's in parallel, One of the units is used strictly as an encoder during the memory write cycle. Both controls S0 and Sl are grounded, The encoder chip will generate the 6-bit check word for memory storage along with the 16-bit data. The second of the two EDAC's will be used as a decoder during the memory read cycle. This decoder chip requires timing pulses for correct operation. Control S1 is set low and S0 high as the memory read cycle begins. After the memory output data is valid, the control S1 input is moved from the low to a high. This low-to-high transition latches the 22-bit word from memory into internal registers of this second EDAC and enables the two error flags. If no error occurs, the CPU can accept the 16-bit word directly from memory. If a single error has occurred, the CPU must move the control SO input from the high to a low to output corrected data and the error syndrome bits. Any dual error should be an interrupt condition. In most applications, status registers will be used to keep tabs on error flags and error syndrome bits. If repeated patterns of error flags and syndrome bits occur, the CPU will be able to recognize these symptoms as a "hard" error. The syndrome bits can be used to pinpoint the faulty memory chip, See Figure 3.
Figure 2: Error Detection and Correction Using a Single EDAC Unit
3/10
54HSC/T630
S1 L H H
S0 H H L
Function Start READ Latch data & flag errors Correct data & Output syndrome bits
Figure 3: Error Detection and Correction Using Two EDAC Units
DEFINITION OF SUBGROUPS
Subgroup 1 2 3 9 10 11 Definition Static characteristics specified in Table 6 at +25°C Static characteristics specified in Table 6 at +125°C Static characteristics specified in Table 6 at -55°C Switching characteristics specified in Table 7 at +25°C Switching characteristics specified in Table 7 at +125°C Switching characteristics specified in Table 7 at -55°C
DC CHARACTERISTICS AND RATINGS
Parameter Supply Voltage Input Voltage Current Through Any Pin Operating Temperature Storage Temperature Min -0.5 VSS-0.3 -20 -55 -65 Max 7 VDD+0.3 +20 125 150 Units V V mA °C °C Note: Stresses above those listed may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these conditions, or at any other condition above those indicated in the operations section of this specification, is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Table 5: Absolute Maximum Ratings
4/10
54HSC/T630
Total dose radiation not exceeding 3x105 Rad(SI) Symbol VDD VIH1 VIL1 VIH2 VIL2 VOH1 VOL1 VOH2 VOL2 I1L I1H I2L I2H IDD Parameter Supply Voltage TTL Input High Voltage TTL Input Low Voltage CMOS Input High Voltage CMOS Input Low Voltage TTL Output High Voltage TTL Output Low Voltage CMOS Output High Voltage CMOS Output Low Voltage Input Low Current Input High Current IO Low Current IO High Current Power Supply Current Conditions IOH = -4mA IOL = 12mA (CB or DB), IOL = 4mA (SEF or DEF) IOH = -4mA IOL = 12mA (CB or DB), IOL = 4mA (SEF or DEF) VDD = 5.5, VIN = VSS VDD = 5.5, VIN = VDD VDD = 5.5, VIN = VSS VDD = 5.5, VIN = VDD VDD = Max, S0 & S1 at 5.5V, All CB & DB pins grounded, DEF & SEF open Min 4.5 2.0 3.5 2.4 VDD-0.5 Typ 5.0 Max 5.5 0.8 1.5 0.4 0.5 -10 50 -50 50 1 Units V V V V V V V V V µA µA µA µA mA
VDD = 5V±10%, over full operating temperature range. Mil-Std-883, method 5005, subgroups 1, 2, 3 Parameters at higher radiation levels available on request.
Table 6: Electrical Characteristics
AC ELECTRICAL CHARACTERISTICS
Parameter From To (Input) (Output) Min. Max. Units Conditions (HST) CB CB DEF SEF CB, DB CB, DB CB, DB CB, DB 30 15 58 58 29 29 40 45 45 65 ns ns ns ns ns ns ns ns ns ns S0 = 0V, S1 = 0V S0 = 0V, S1 = 0V S0 = 3V S0 = 3V S1 = 3V (fig. 5) S1 = 3V (fig. 4) S1 = 3V (fig. 5) S1 = 3V (fig. 4) Conditions (HSC) S0 = 0V, S1 = 0V S0 = 0V, S1 = 0V S0 = VDD-1V S0 = VDD-1V S1 = VDD-1V (fig. 5) S1 = VDD-1V (fig. 4) S1 = VDD-1V (fig. 5) S1 = VDD-1V (fig. 4) -
DB tPLH Propogation delay time, low-to-high-level output (Note 4) DB tPLH Propogation delay time, low-to-high-level output (Note 4) S1 tPLH Propogation delay time, low-to-high-level output (Note 5) S1 tPLH Propogation delay time, low-to-high-level output (Note 5) S0 tPZH Output enable time to high level (Note 6) S0 tPZL Output enable time to low level (Note 6) S0 tPHZ Output disable time to high level (Note 7) S0 tPLZ Output disable time to low level (Note 7) CB, DB tS Set-up time to S1 > CB, DB tH Hold time after S1 >
1. VDD = 5V ±10% and CL = 50pF, over full operating temperature and total dose = 300K Rad(Si) 2. Input Pulse VSS to 3.0 Volts.(TTL), VDD -1V (CMOS). 3. Times Measurement Reference Level 1.5 Volts. 4. These parameters describe the time intervals taken to generate the check word during the memory write cycle. 5. These parameters describe the time intervals taken to flag errors during memory read cycle. 6. These parameters describe the time intervals taken to correct and output the data word and to generate and output the syndrome error code during the memory read cycle. 7. These parameters describe the time intervals taken to disable the CB & DB buses in preparation for a new data word during the memory read cycle. 8. Mil-Std-883, method 5005, subgroups 9, 10, 11 9. Parameters at higher radiation levels available on request.
Table 7: AC Electrical Characteristics
5/10
Others parts begin by 54
54-1 54-2 54-3 54-4 54-5 54-6 54-7 54-8 54-9 54-10 54-11 54-12 54-13
|
|
|
