DS1248W/120+ ,1024K NV SRAM with Phantom ClockFEATURES PIN CONFIGURATIONS Real-Time Clock (RTC) Keeps Track of Hundredths of Seconds, Minutes, ..
DS1248W-120+ ,1024K NV SRAM with Phantom Clock19-6078; Rev 11/11 DS1248/DS1248P 1024K NV SRAM with Phantom Clock
DS1248W-120+ ,1024K NV SRAM with Phantom Clock19-6078; Rev 11/11 DS1248/DS1248P 1024K NV SRAM with Phantom Clock
DS1248WP-120+ ,1024K NV SRAM with Phantom ClockFEATURES PIN CONFIGURATIONS Real-Time Clock (RTC) Keeps Track of Hundredths of Seconds, Minutes, ..
DS1248Y-70+ ,1024K NV SRAM with Phantom ClockFEATURES PIN CONFIGURATIONS Real-Time Clock (RTC) Keeps Track of Hundredths of Seconds, Minutes, ..
DS1248Y-70IND+ ,1024K NV SRAM with Phantom ClockFEATURES PIN CONFIGURATIONS Real-Time Clock (RTC) Keeps Track of Hundredths of Seconds, Minutes, ..
DTB123EK , -500mA / -50V Digital transistors (with built-in resistors)
DTB123EK , -500mA / -50V Digital transistors (with built-in resistors)
DTB123YK , PNP -500mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTB123YS , Digital transistors (built-in resistors)
DTB123YU , PNP -500mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTB133HK , Digital transistors (built-in resistors)
DS1248W/120+-DS1248W-120+-DS1248WP-120+-DS1248Y-70+-DS1248Y-70IND+-DS1248YP-70+
1024K NV SRAM with Phantom Clock
FEATURES Real-Time Clock (RTC) Keeps Track of
Hundredths of Seconds, Minutes, Hours,
Days, Date of the Month, Months, and Years 128K x 8 NV SRAM Directly Replaces
Volatile Static RAM or EEPROM Embedded Lithium Energy Cell Maintains
Calendar Operation and Retains RAM Data Watch Function is Transparent to RAM
Operation Automatic Leap Year Compensation Valid
Up to 2100 Full 10% Operating Range Over 10 Years of Data Retention in the
Absence of Power Lithium Energy Source is Electrically
Disconnected to Retain Freshness Until
Power is Applied for the First Time DIP Module Only
Standard 32-Pin JEDEC Pinout Underwriters Laboratories (UL) Recognized
(/qa/info/ul/) PowerCap Module Board Only
Surface Mountable Package for Direct
Connection to PowerCap Containing
Battery and Crystal
Replaceable Battery (PowerCap)
Pin-for-Pin Compatible with DS1244P and
DS1251P
PIN CONFIGURATIONS
Encapsulated DIP
(740-mil Flush) RST
N.C.
13
10
11
12
14
31 A14 A7
A5
A4
A3
A2
A1
A0
DQ1
DQ0
32
30
29
28
27
26
25
24
23
22
21
19
20 A16
A12
A6
DQ2
GND
15
16
18
17
VCC
A15
WE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ5
DQ6
DQ4
DQ3
DS1248 TOP VIEW RST 2 A15 A16
N.C. VCC
WE OE
CE DQ7
DQ6
DQ5 DQ4
DQ3
DQ2 DQ1
DQ0
GND 5 6 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+ PowerCap)
DS1248P
DS1248/DS1248P
1024K NV SRAM with Phantom Clock 19-6078; Rev 11/11
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
ORDERING INFORMATION
PART TEMP RANGE VCC RANGE PIN-PACKAGE DS1248Y-70+ 0°C to +70°C 5V ±10% 32 EDIP
DS1248Y-70IND+ -40°C to +85°C 5V ±10% 32 EDIP
DS1248YP-70+ 0°C to +70°C 5V ±10% 34 PowerCap*
DS1248W-120+ 0°C to +70°C 3.3V ±10% 32 EDIP
DS1248W-120IND+ -40°C to +85°C 3.3V ±10% 32 EDIP
DS1248WP-120+ 0°C to +70°C 3.3V ±10% 34 PowerCap*
DS1248WP-120IND+ -40°C to +85°C 3.3V ±10% 34 PowerCap*
+ Denotes a lead(Pb)-free/RoHS-compliant package.
* DS9034PCX+ or DS9034I-PCX+ (PowerCap) required. Must be ordered separately.
DETAILED DESCRIPTION The DS1248 1024K NV SRAM with phantom clock is a fully static, nonvolatile RAM (organized as
128K words by 8 bits) with a built-in real-time clock. The DS1248 has a self-contained lithium energy
source and control circuitry, which constantly monitors VCC for an out-of-tolerance condition. When such condition occurs, the lithium energy source is automatically switched on and writes protection is
unconditionally enabled to prevent garbled data in both the memory and real-time clock.
PACKAGES The DS1248 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 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
DS1248P after completion of the surface mount process. Mounting the PowerCap after the surface mount
process prevents damage to the crystal and battery because of 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.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
PIN DESCRIPTION
PIN NAME FUNCTION EDIP PowerCap 1 RST Active-Low Reset Input. This pin has an internal pullup resistor
connected to VCC. 3 A16
Address Inputs 32 A14 30 A12 25 A7 24 A6 23 A5 22 A4 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 In/Data Out
14 15 DQ1
15 14 DQ2
17 13 DQ3
18 12 DQ4
19 11 DQ5
20 10 DQ6
21 9 DQ7
22 8 CE Active-Low Chip-Enable Input
24 7 OE Active-Low Output-Enable Input
29 6 WE Active-Low Write-Enable Input
30 4, 33, 34 N.C. No Connect
32 5 VCC Power-Supply Input
16 17 GND Ground
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
RAM READ MODE The DS1248 executes a read cycle whenever WE (write enable) is inactive (high) and CE (chip enable) is
active (low). The unique address specified by the 17 address inputs (A0–A16) defines which of the 128k
bytes of data is to be accessed. Valid data will be available to the eight data-output drivers within tACC
(access time) after the last address input signal is stable, providing that CE and OE (output enable) access
times and states are also satisfied. If OE and CE access times are not satisfied, then data access must be
measured from the later occurring signal (CE or OE) and the limiting parameter is either tCO for CE or tOE
for OE, rather than address access.
RAM WRITE MODE The DS1248 is in the write mode whenever the WE and CE signals are in the active (low) state after
address inputs are stable. The latter occurring falling edge of CE or WE will determine the start of the
write cycle. The write cycle is terminated by the earlier rising edge of CEor WE. All address inputs must
be kept valid throughout the write cycle. WE must return to the high state for a minimum recovery time
(tWR) before another cycle can be initiated. The OE control signal should be kept inactive (high) during
write cycles to avoid bus contention. However, if the output bus has been enabled (CE and OE active)
then WE will disable the outputs in tODW from its falling edge.
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. 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 VPF, access to the device is inhibited. If VPF is less than VBAT, the device power is
switched from VCC to the backup supply (VBAT) when VCC drops below VPF. If VPF is greater than VBAT,
the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VBAT. RTC
operation and SRAM data are maintained from the battery until VCC is returned to nominal levels.
All control, data, and address signals must be powered down when VCC is powered-down.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
PHANTOM CLOCK OPERATION Communication with the phantom clock is established by pattern recognition on a serial bit stream of
64 bits, which must be matched by executing 64 consecutive write cycles containing the proper data on
DQ0. All accesses that occur prior to recognition of the 64-bit pattern are directed to memory.
After recognition is established, the next 64 read or write cycles either extract or update data in the
phantom clock, and memory access is inhibited.
Data transfer to and from the timekeeping function is accomplished with a serial bit stream under control
of chip enable, output enable, and write enable. Initially, a read cycle to any memory location using the
CE and OE control of the phantom clock starts the pattern recognition sequence by moving a pointer to
the first bit of the 64-bit comparison register. Next, 64 consecutive write cycles are executed using the CE
and WE control of the SmartWatch. These 64 write cycles are used only to gain access to the phantom
clock. Therefore, any address to the memory in the socket is acceptable. However, the write cycles
generated to gain access to the phantom clock are also writing data to a location in the mated RAM. The
preferred way to manage this requirement is to set aside just
one address location in RAM as a phantom clock scratch pad. When the first write cycle is executed, it is
compared to bit 0 of the 64-bit comparison register. If a match is found, the pointer increments to the next
location of the comparison register and awaits the next write cycle. If a match is not found, the pointer
does not advance and all subsequent write cycles are ignored. If a read cycle occurs at any time during
pattern recognition, the present sequence is aborted and the comparison register pointer is reset. Pattern
recognition continues for a total of 64 write cycles as described above until all the bits in the comparison
register have been matched (Figure 1). With a correct match for 64 bits, the phantom clock is enabled and
data transfer to or from the timekeeping registers can proceed. The next 64 cycles will cause the phantom
clock to either receive or transmit data on DQ0, depending on the level of the OE pin or the WE pin.
Cycles to other locations outside the memory block can be interleaved with CE cycles without
interrupting the pattern recognition sequence or data transfer sequence to the phantom clock.
PHANTOM CLOCK REGISTER INFORMATION The phantom clock information is contained in eight registers of 8 bits, each of which is sequentially
accessed 1 bit at a time after the 64-bit pattern recognition sequence has been completed. When updating
the phantom clock registers, each register must be handled in groups of 8 bits. Writing and reading
individual bits within a register could produce erroneous results. These read/write registers are defined in
Figure 2.
Data contained in the phantom clock register is in binary-coded decimal format (BCD). Reading and
writing the registers is always accomplished by stepping through all eight registers, starting with bit 0 of
register 0 and ending with bit 7 of register 7.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
Figure 1. Phantom Clock Register Definition
NOTE: THE PATTERN RECOGNITION IN HEX IS C5, 3A, A3, 5C, C5, 3A, A3, 5C. THE ODDS OF THIS PATTERN BEING ACCIDENTALLY DUPLICATED AND CAUSING INADVERTENT ENTRY TO THE PHANTOM CLOCK IS
LESS THAN 1 IN 1019. THIS PATTERN IS SENT TO THE PHANTOM CLOCK LSB TO MSB.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
Figure 2. Phantom Clock Register Definition
AM/PM/12/24-MODE Bit 7 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour
mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour
mode, bit 5 is the 20-hour bit (20–23 hours).
OSCILLATOR AND RESET BITS Bits 4 and 5 of the day register are used to control the RST and oscillator functions. Bit 4 controls the
RST (pin 1). When the RST bit is set to logic 1, the RST input pin is ignored. When the RST bit is set to
logic 0, a low input on the RST pin will cause the phantom clock to abort data transfer without changing
data in the watch registers. Bit 5 controls the oscillator. When set to logic 1, the oscillator is off. When set
to logic 0, the oscillator turns on and the watch becomes operational. These bits are shipped from the
factory set to a logic 1.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
ZERO BITS Registers 1, 2, 3, 4, 5, and 6 contain one or more bits, which will always read logic 0. When writing these
locations, either a logic 1 or 0 is acceptable.
BATTERY LONGEVITY The DS1248 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 DS1248 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 DS1248 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 DS1248 will
be much longer than 10 years since no lithium battery energy is consumed when VCC is present.
See “Conditions of Acceptability” at /TechSupport/QA/ntrl.htm
CLOCK ACCURACY (DIP MODULE) The DS1248 is guaranteed to keep time accuracy to within ±1 minute per month at +25°C. The clock is
calibrated at the factory by Maxim using special calibration nonvolatile tuning elements and does not
require additional calibration. For this reason, methods of field clock calibration are not available and not
necessary.
CLOCK ACCURACY (POWERCAP MODULE) The DS1248P 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 (35ppm) at +25°C.
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground (5V product)………………………..-0.3V to +6.0V (3.3V product)………………… …..-0.3V to +4.6V
Storage Temperature Range EDIP ..........................................................................................................................-40ºC to +85ºC PowerCap ................................................................................................................-55°C to +125°C
Lead Temperature (soldering, 10s) ................................................................................................... +260°C
Note: EDIP is wave or hand-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 conditions beyond those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time can affect
reliability.
OPERATING RANGE
RANGE TEMP RANGE
(NONCONDENSING) VCC (V) Commercial 0°C to +70°C 3.3 ±10% or 5 ±10%
Industrial -40°C to +85°C 3.3 ±10% or 5 ±10%
RECOMMENDED OPERATING CONDITIONS Over the Operating Range
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Logic 1 VCC = 5V ±10% VIH 2.2 VCC + 0.3 V 11 VCC = 3.3V ±10% 2.0 VCC + 0.3
Logic 0 VCC = 5V ±10% VIL -0.3 +0.8 V 11 VCC = 3.3V ±10% -0.3 +0.6
DC ELECTRICAL CHARACTERISTICS Over the Operating Range (5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Leakage Current IIL -1.0 +1.0 µA 12
I/O Leakage Current
CE ≥ VIH ≤ VCC IIO -1.0 +1.0 µA
Output Current at 2.4V IOH -1.0 mA
Output Current at 0.4V IOL 2.0 mA
Standby Current CE = 2.2V ICCS1 5 10 mA
Standby Current
CE = VCC - 0.5V ICCS2 3.0 5.0 mA
Operating Current tCYC = 70ns ICC01 85 mA
Write Protection Voltage VPF 4.25 4.37 4.50 V 11
DS1248/DS1248P 1024K NV SRAM with Phantom Clock
DC ELECTRICAL CHARACTERISTICS Over the Operating Range (3.3V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Leakage Current IIL -1.0 +1.0 µA 12
I/O Leakage Current
CE ≥ VIH ≤ VCC IIO -1.0 +1.0 µA
Output Current at 2.4V IOH -1.0 mA
Output Current at 0.4V IOL 2.0 mA
Standby Current CE = 2.2V ICCS1 5 7 mA
Standby Current
CE = VCC - 0.5V ICCS2 2.0 3.0 mA
Operating Current tCYC = 70ns ICC01 50 mA
Write Protection Voltage VPF 2.80 2.86 2.97 V 11
Battery Switchover Voltage VSO VBAT or
VPF V 11
CAPACITANCE (TA = +25°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Capacitance CIN 5 10 pF
Input/Output Capacitance CI/O 5 10 pF
MEMORY AC ELECTRICAL CHARACTERISTICS Over the Operating Range (5V)
PARAMETER SYMBOL DS1248Y-70 UNITS NOTES MIN MAX Read Cycle Time tRC 70 ns
Access Time tACC 70 ns
OE to Output Valid tOE 35 ns
CE to Output Valid tCO 70 ns
OE or CE to Output Active tCOE 5 ns 5
Output High-Z from Deselection tOD 25 ns 5
Output Hold from Address Change tOH 5 ns
Write Cycle Time tWC 70 ns
Write Pulse Width tWP 50 ns 3
Address Setup Time tAW 0 ns
Write Recovery Time tWR 0 ns
Output High-Z from WE tODW 25 ns 5
Output Active from WE tOEW 5 ns 5
Data Setup Time tDS 30 ns 4
Data Hold Time from WE tDH 5 ns 4
