DS1501YZ+ Maxim Integrated Products, DS1501YZ+ Datasheet - Page 13

• Manufacturer Part Number: DS1501YZ+
• Description: IC RTC WDOG Y2KC 5.0V 28-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/WDT/NVSRAM/Y2Kr

Specifications of DS1501YZ+

• Memory Size: 2K (256 x 8)
• Time Format: HH:MM:SS (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The third method of reading the time and date uses the alarm function. The alarm can be configured to activate
once per second, and the time-of-day alarm-interrupt enable bit (TIE) is enabled. The TE bit should always be
enabled. When the IRQ pin goes active, the time and date information does not change until the next update.
SETTING THE CLOCK
It is recommended to halt updates to the external set of double-buffered RTC registers when writing to the clock.
The (TE) bit should be used as described above before loading the RTC registers with the desired RTC count (day,
date, and time) in 24-hour BCD format. Setting the TE bit to 1 transfers the new values written to the internal RTC
registers and allows normal operation to resume.
CLOCK ACCURACY
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match between
the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed. Additional
error is added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the
oscillator circuit can result in the clock running fast.
A standard 32.768kHz quartz crystal should be directly connected to the DS1501 X1 and X2 oscillator pins. The
crystal selected for use should have a specified load capacitance (C
accordingly. An external 32.768kHz oscillator can also drive the DS1501. When using an external oscillator the X2
pin must be left open. The DS1511 contains an embedded crystal and is factory trimmed to be better than ±1
min/month at +25
Refer to Application Note 58: Crystal Considerations for Dallas Real-Time Clocks for detailed information.
Table 2. Register Map
Note: 0 = 0 and are read only.
POWER-UP DEFAULT STATES
These bits are set upon power-up: EOSC = 0, E32K = 0, TIE = 0, KIE = 0, WDE = 0, and WDS = 0. Unless
otherwise specified, the state of the control/RTC/SRAM bits in the DS1501/DS1511 is not defined upon initial
power application; the DS1501/DS1511 should be properly configured/defined during initial configuration.
ADDRESS
14H-1FH
0AH
0BH
0CH
0DH
0EH
00H
01H
02H
03H
04H
05H
06H
07H
08H
09H
0FH
10H
11H
12H
13H
EOSC
BLF1
AM1
AM2
AM3
AM4
TE
B7
°
0
0
0
0
0
C.
E32K
Dy/Dt
BLF2
CS
B6
0
0
0
0
0.1 Second
10 Century
10 Second
10 Year
10 Seconds
10 Seconds
10 Minutes
10 Minutes
BB32
BME
PRS
B5
0
10 Hours
10 Hours
10 Date
10 Date
Extended RAM Address
Extended RAM Data
10 Month
PAB
TPE
Reserved
Reserved
Reserved
B4
0
DATA
13 of 22
TDF
TIE
B3
0
DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
KSF
KIE
B2
0.01 Second
Day/Date
Seconds
Seconds
Minutes
Century
Minutes
Second
Month
Hour
Date
Year
Hour
L
) of either 6pF or 12.5pF, and the CS bit set
WDF
WDE
Day
B1
IRQF
WDS
B0
Alarm Day/Date
Alarm Seconds
Alarm Minutes
RAM Address
Alarm Hours
FUNCTION
RAM Data
Watchdog
Watchdog
Control A
Control B
Seconds
Minutes
Century
Month
Hours
Date
Year
Day
1–7/1–31
RANGE
00–FF
00–FF
00–59
00–59
00–23
01–31
01–12
00–99
00–39
00–59
00–59
00–23
00–99
00–99
BCD
1–7