DS1746W-120+ ,Y2K-Compliant, Nonvolatile Timekeeping RAMsFEATURES PIN CONFIGURATIONS Integrated NV SRAM, Real-Time Clock, TOP VIEW Crystal, Power-Fail C ..
DS1746W-120IND ,Y2K-Compliant, Nonvolatile Timekeeping RAMsFEATURES PIN ASSIGNMENT Integrated NV SRAM, real time clock,NC1 32 VCCcrystal, power-fail control ..
DS1746WP-120 ,Y2K-Compliant, Nonvolatile Timekeeping RAMsPIN DESCRIPTIONA0–A16 – Address InputCE – Chip EnableOE – Output EnableWE – Write EnableV – Po ..
DS1746WP-120+ ,Y2K-Compliant, Nonvolatile Timekeeping RAMs DS1746/DS1746P Y2K-Compliant, N onvolatile Timekeeping RAMs
DS1747-70+ ,Y2K-Compliant, Nonvolatile Timekeeping RAMs DS1747/DS1747P Y2K-Compliant, Nonvolatile Timekeeping RAMs
DS1747-70IND ,Y2K-Compliant, Nonvolatile Timekeeping RAMsFEATURES PIN CONFIGURATIONS Integrated NV SRAM, Real-Time Clock (RTC), Crystal, Power-Fail Cont ..
DV74AC244 , Octal buffer/Line Driver with 3-state Outputs
DVIULC6-2P6 ,Ultra Low capacitance 2 lines ESD protectionApplicationsBenefits■ DVI ports up to 1.65 Gb/s■ ESD standards compliance guaranteed at ■ IEEE 1394 ..
DVIULC6-4SC6 ,Ultralow capacitance ESD protectionFeatures■ 4-line ESD protection (IEC 61000-4-2)■ Protects V when applicableBUS■ Ultralow capacitanc ..
DW01 , One Cell Lithium-ion/Polymer Battery Protection IC
DW01 , One Cell Lithium-ion/Polymer Battery Protection IC
DW01 , One Cell Lithium-ion/Polymer Battery Protection IC
DS1746-70+-DS1746P-70+-DS1746W/120+-DS1746W-120+-DS1746WP-120+
Y2K-Compliant, Nonvolatile Timekeeping RAMs
FEATURES Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source Clock Registers are Accessed Identically to the Static RAM. These Registers are Resident in the Eight Top RAM Locations. Century Byte Register (i.e., Y2K Compliant) Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap Year Compensation Valid Up to the Year 2100 Battery Voltage-Level Indicator Flag Power-Fail Write Protection Allows for ±10% VCC Power Supply Tolerance Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time DIP Module Only Standard JEDEC Byte-Wide 128k x 8 Static RAM Pinout PowerCap Module Board Only Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal Replaceable Battery (PowerCap) Power-On Reset Output Pin-for-Pin Compatible with Other Densities of DS174xP Timekeeping RAM Also Available in Industrial Temperature Range: -40°C to +85°C Underwriters Laboratories (UL) Recognized
PIN CONFIGURATIONS
Encapsulated DIP N.C.
13 3 6 8 10
11
12
14
31 A14 A7 A5
A4
A3
A2 A1
A0
DQ1
DQ0
VCC
A15
N.C.
WE A13
A8
A9
A11
OE A10
CE
DQ7
DQ5
DQ6
32
30
29
28 27
26 25
24 23
22
21
19
20 A16
A12
A6
DQ2
GND
15
16
18
17
DQ4
DQ3
Maxim DS1746
TOP VIEW N.C. 2 3 A15 A16
RST VCC
OE
CE DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0 GND 5 6 7 8 9 10 11 12 13 14 15 16 17
N.C. A14 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18
A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
34 N.C.
X1 GND VBAT X2
PowerCap Module Board (Uses DS9034PCX+ or DS9034I-PCX+ PowerCap)
Maxim DS1746P
WE
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
PIN DESCRIPTION PIN NAME FUNCTION PDIP PowerCap 1, 30 1, 33, 34 N.C. No Connection 2 3 A16
Address Input 32 A14 4 30 A12 5 25 A7 6 24 A6 7 23 A5 8 22 A4 9 21 A3 10 20 A2 11 19 A1 12 18 A0 23 28 A10 25 29 A11 26 27 A9 27 26 A8 28 31 A13 31 2 A15 13 16 DQ0
Data Input/Output
14 15 DQ1 15 14 DQ2 17 13 DQ3 18 12 DQ4 19 11 DQ5 20 10 DQ6 21 9 DQ7 16 17 GND Ground 22 8 CE Active-Low Chip Enable Input 24 7 OE Active-Low Output Enable Input 29 6 WE Active-Low Write-Enable Input 32 5 VCC Power-Supply Input 4 RST Active-Low Power-Fail Output, Open Drain. Requires a pullup resistor for proper operation. X1, X2, VBAT
Crystal Connection, VBAT Battery Connection. UL recognized to ensure against reverse charging when used with a lithium battery (www.maximintegrated.com/qa/info/ul/)
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
ORDERING INFORMATION
PART VOLTAGE RANGE (V) TEMP RANGE PIN-PACKAGE TOP MARK†
DS1746-70+ 5.0 0°C to +70°C 32 EDIP (0.740a) DS1746+070 DS1746-70IND+ 5.0 -40°C to +85°C 32 EDIP (0.740a) DS1746+070 IND
DS1746P-70+ 5.0 0°C to +70°C 34 PowerCap* DS1746P+70
DS1746P-70IND+ 5.0 -40°C to +85°C 34 PowerCap* DS1746P+070 IND
DS1746W-120+ 3.3 0°C to +70°C 32 EDIP (0.740a) DS1746W+120 DS1746W-120IND+ 3.3 -40°C to +85°C 32 EDIP (0.740a) DS1746W+120 IND
DS1746WP-120+ 3.3 0°C to +70°C 34 PowerCap* DS1746WP+120
DS1746WP-120IND+ 3.3 -40°C to +85°C 34 PowerCap* DS1746WP+120 IND +Denotes a lead(Pb)-free/RoHS-compliant package. The top mark will include a “+” symbol on lead-free devices. *DS9034-PCX+ or DS9034I-PCX+ required (must be ordered separately). † An “IND” anywhere on the top mark denotes an industrial temperature grade device.
DESCRIPTION The DS1746 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 128k x 8 nonvolatile static RAM. User access to all registers within the DS1746 is accomplished with a byte-wide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for the date of each month and leap year are made automatically. The RTC clock registers are double buffered to avoid access of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1746 also contains its own power-fail circuitry, which deselects the device when the VCC supply is in an out of tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
Figure 1. Block Diagram PACKAGES The DS1746 is available in two packages (32-pin DIP and 34-pin PowerCap module). The 32-pin DIP style module integrates the crystal, lithium energy source, and silicon all in one package. The 34-pin PowerCap Module Board is designed with contacts for connection to a separate PowerCap (DS9034PCX) that contains the crystal and battery. This design allows the PowerCap to be mounted on top of the DS1746P after the completion of the surface mount process. Mounting the PowerCap after the surface mount process prevents damage to the crystal and battery due to the high temperatures required for solder reflow. The PowerCap is keyed to prevent reverse insertion. The PowerCap Module Board and PowerCap are ordered separately and shipped in separate containers.
CLOCK OPERATIONS—READING THE CLOCK While the double-buffered register structure reduces the chance of reading incorrect data, internal updates to the DS1746 clock registers should be halted before clock data is read to prevent reading of data in transition. However, halting the internal clock register updating process does not affect clock accuracy. Updating is halted when a one is written into the read bit, bit 6 of the century register (see Table 2). As long as a one remains in that position, updating is halted. After a halt is issued, the registers reflect the count, that is day, date, and time that was current at the moment the halt command was issued. However, the internal clock registers of the double-buffered system continue to update so that the clock accuracy is not affected by the access of data. All of the DS1746 registers are updated simultaneously after the internal clock register updating process has been re-enabled. Updating is within a second after the read bit is written to zero. The READ bit must be a zero for a minimum of 500µs to ensure the external registers will be updated.
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
Table 1. Truth Table
VCC CE OE WE
MODE DQ POWER VCC>VPF
VIH X X Deselect High-Z Standby VIL X VIL Write Data In Active VIL VIL VIH Read Data Out Active VIL VIH VIH Read High-Z Active VSO
SETTING THE CLOCK
As shown in Table 2, bit 7 of the Control register is the W (write) bit. Setting the W bit to 1 halts updates to the device registers. The user can subsequently load correct date and time values into all eight registers, followed by a write cycle of 00h to the Control register to clear the W bit and transfer those new settings into the clock, allowing timekeeping operations to resume from the new set point.
Again referring to Table 2, bit 6 of the Control register is the R (read) bit. Setting the R bit to 1 halts updates to the device registers. The user can subsequently read the date and time values from the eight registers without those contents possibly changing during those I/O operations. A subsequent write cycle of 00h to the Control register to clear the R bit allows timekeeping operations to resume from the previous set point.
The pre-existing contents of the Control register bits 0:5 (Century value) are ignored/unmodified by a write cycle to Control if either the W or R bits are being set to 1 in that write operation.
The pre-existing contents of the Control register bits 0:5 (Century value) will be modified by a write cycle to Control if the W bit is being cleared to 0 in that write operation.
The pre-existing contents of the Control register bits 0:5 (Century value) will not be modified by a write cycle to Control if the R bit is being cleared to 0 in that write operation. STOPPING AND STARTING THE CLOCK OSCILLATOR The clock oscillator may be stopped at any time. To increase the shelf life, the oscillator can be turned off to minimize current drain from the battery. The OSC bit is the MSB (bit 7) of the seconds registers (see Table 2). Setting it to a one stops the oscillator. FREQUENCY TEST BIT As shown in Table 2, bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to logic “1” and the oscillator is running, the LSB of the seconds register will toggle at 512 Hz. When the seconds register is being read, the DQ0 line will toggle at the 512 Hz frequency as long as conditions for access remain valid (i.e., CE low, OE low, WE high, and address for seconds register remain valid and stable). CLOCK ACCURACY (DIP MODULE) The DS1746 is guaranteed to keep time accuracy to within ±1 minute per month at 25°C. The RTC is calibrated at the factory by Maxim using nonvolatile tuning elements, and does not require additional calibration. For this reason, methods of field clock calibration are not available and not necessary. The electrical environment also affects clock accuracy and caution should be taken to place the RTC in the
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
CLOCK ACCURACY (PowerCap MODULE) The DS1746 and DS9034PCX are each individually tested for accuracy. Once mounted together, the module will typically keep time accuracy to within ±1.53 minutes per month (35 ppm) at 25°C. The electrical environment also affects clock accuracy and caution should be taken to place the RTC in the lowest-level EMI section of the PC board layout. For additional information, refer to Application Note 58. Table 2. Register Map
ADDRESS DATA FUNCTION RANGE B7 B6 B5 B4 B3 B2 B1 B0
1FFFF 10 Year Year Year 00-99
1FFFE X X X 10 Month Month Month 01-12
1FFFD X X 10 Date Date Date 01-31
1FFFC BF FT X X X Day Day 01-07
1FFFB X X 10 Hour Hour Hour 00-23 1FFFA X 10 Minutes Minutes Minutes 00-59
1FFF9 OSC 10 Seconds Seconds Seconds 00-59
1FFF8 W R 10 Century Century Century 00-39
OSC = Stop Bit R = Read Bit FT = Frequency Test
W = Write Bit X = See Note BF = Battery Flag Note: All indicated “X” bits are not used but must be set to “0” during a write cycle to ensure proper clock operation. RETRIEVING DATA FROM RAM OR CLOCK The DS1746 is in the read mode whenever OE (output enable) is low, WE (write enable) is high, and CE (chip enable) is low. The device architecture allows ripple-through access to any of the address locations in the NV SRAM. Valid data will be available at the DQ pins within tAA after the last address input is stable, providing that the CE and OE access times and states are satisfied. If CE or OE access times and states are not met, valid data will be available at the latter of chip enable access (tCEA) or at output enable access time (tOEA). The state of the data input/output pins (DQ) is controlled by CE and OE. If the outputs are activated before tAA, the data lines are driven to an intermediate state until tAA . If the address inputs are changed while CE and OE remain valid, output data will remain valid for output data hold time (tOH) but will then go indeterminate until the next address access. WRITING DATA TO RAM OR CLOCK The DS1746 is in the write mode whenever WE, and CE are in their active state. The start of a write is referenced to the latter occurring transition of WE, or CE. The addresses must be held valid throughout the cycle. CE or WE must return inactive for a minimum of tWR prior to the initiation of another read or write cycle. Data in must be valid tDS prior to the end of write and remain valid for tDS afterward. In a typical application, the OE signal will be high during a write cycle. However, OE can be active provided that care is taken with the data bus to avoid bus contention. If OE is low prior to WE transitioning low the data bus can become active with read data defined by the address inputs. A low transition on WE will then disable the output tWEZ after WE goes active.
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
DATA-RETENTION MODE The 5V device is fully accessible and data can be written or read only when VCC is greater than VPF. However, when VCC is below the power-fail point, VPF, (point at which write protection occurs) the internal clock registers and SRAM are blocked from any access. At this time the power fail reset output signal (RST) is driven active and will remain active until VCC returns to nominal levels. When VCC falls below the battery switch point VSO (battery supply level), device power is switched from the VCC pin to the backup battery. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. The 3.3V device is fully accessible and data can be written or read only when VCC is greater than VPF. When VCC falls below the power fail point, VPF, access to the device is inhibited. At this time the power fail reset output signal (RST) is driven active and will remain active until VCC returns to nominal levels. If VPF is less than VSO, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VPF. If VPF is greater than VSO, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VSO. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. The RST signal is an open drain output and requires a pull up. Except for the RST, all control, data, and address signals must be powered down when VCC is powered down. BATTERY LONGEVITY The DS1746 has a lithium power source that is designed to provide energy for clock activity, and clock and RAM data retention when the VCC supply is not present. The capability of this internal power supply is sufficient to power the DS1746 continuously for the life of the equipment in which it is installed. For specification purposes, the life expectancy is 10 years at 25°C with the internal clock oscillator running in the absence of VCC power. Each DS1746 is shipped from Maxim with its lithium energy source disconnected, guaranteeing full energy capacity. When VCC is first applied at a level greater than VPF, the lithium energy source is enabled for battery backup operation. Actual life expectancy of the DS1746 will be much longer than 10 years since no lithium battery energy is consumed when VCC is present. BATTERY MONITOR The DS1746 constantly monitors the battery voltage of the internal battery. The Battery Flag bit (bit 7) of the day register is used to indicate the voltage level range of the battery. This bit is not writable and should always be a one when read. If a zero is ever present, an exhausted lithium energy source is indicated and both the contents of the RTC and RAM are questionable.
DS1746/DS1746P Y2K-Compliant, Nonvolatile Timekeeping RAMs
ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground 5.5V Version…………………………..………………………………..……………………..-0.3V to +6.0V 3.3V Version…………………………………………………………………………………..-0.3V to +4.6V Storage Temperature Range EDIP ...................................................……………………...………………..……………….-40°C to +85°C PowerCap ................................................................................................................………...-55°C to +125°C Lead Temperature (soldering, 10s)…........................................................................................……………….+260°C Note: EDIP is hand or wave-soldered only. Soldering Temperature (reflow, PowerCap)......................................................................................…………+260°C
This is a stress rating only and functional operation of the device at these or any other condition above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
OPERATING RANGE RANGE TEMP RANGE VCC Commercial 0°C to +70°C, Noncondensing 3.3V ±10% or 5V ±10% Industrial -40°C to +85°C, Noncondensing 3.3V ±10% or 5V ±10% RECOMMENDED DC OPERATING CONDITIONS (TA = Over the Operating Range) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Logic 1 Voltage All Inputs VCC = 5V ±10%
VCC = 3.3V ±10%
VIH 2.2 VCC + 0.3V V 1
VIH 2.0 VCC + 0.3V V 1
Logic 0 Voltage All Inputs VCC = 5V ± 10%
VCC = 3.3V ± 10%
VIL -0.3 0.8 V 1
VIL -0.3 0.6 V 1 DC ELECTRICAL CHARACTERISTICS (VCC = 5.0V ±10%, TA = Over the Operating Range.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Active Supply Current Icc 85 mA 2, 3, 10
TTL Standby Current CE = VIH) Icc1 6 mA 2, 3
CMOS Standby Current CE ≥VCC-0.2V) Icc2 4 mA 2, 3
Input Leakage Current (any input) IIL -1 +1 µA
Output Leakage Current (any output) IOL -1 +1 µA
Output Logic 1 Voltage (IOUT = -1.0 mA) VOH 2.4 1
Output Logic 0 Voltage (IOUT = +2.1 mA) VOL 0.4 1
Write Protection Voltage VPF 4.25 4.50 V 1
