M48T86
5V PC REAL TIME CLOCK
DATA BRIEFING
DROP-IN REPLACEMENT for PC
COMPUTER CLOCK/CALENDAR
COUNTS SECONDS, MINUTES, HOURS,
DAYS, DAY of the WEEK, DATE, MONTH and
YEAR with LEAP YEAR COMPENSATION
INTERFACED WITH SOFTWARE AS 128
RAM LOCATIONS:
– 14 Bytes of Clock and Control Registers
– 114 Bytes of General Purpose RAM
SELECTABLE BUS TIMING (Intel/Motorola)
THREE INTERRUPTS are SEPARATELY
SOFTWARE-MASKABLE and TESTABLE
– Time-of-Day Alarm (Once/Second to
Once/Day)
– Periodic Rates from 122µs to 500ms
– End-of-Clock Update Cycle
PROGRAMMABLE SQUARE WAVE OUTPUT
SELF-CONTAINED BATTERY and CRYSTAL
in the CAPHAT DIP PACKAGE
PACKAGING INCLUDES a 28-LEAD SOIC
and SNAPHAT® TOP (to be Ordered
Separately)
SOIC PACKAGE PROVIDES DIRECT
CONNECTION for a SNAPHAT TOP
CONTAINS the BATTERY and CRYSTAL
PIN and FUNCTION COMPATIBLE with
bq3285/7A and DS128887
SNAPHAT (SH)
Battery/Crystal
24
28
1
1
PCDIP24 (PC)
Battery/Crystal
CAPHAT
SOH28 (MH)
Figure 1. Logic Diagram
VCC
8
AD0-AD7
DESCRIPTION
The M48T86 is an industry standard real time clock
(RTC). The M48T86 is composed of a lithium energy source, quartz crystal, write-protection circuitry, and a 128 byte RAM array. This provides
the user with a complete subsystem packaged in
either a 24-pin DIP CAPHAT or 28-pin SNAPHAT
SOIC. Functions available to the user include a
non-volatile time-of-day clock, alarm interrupts, a
one-hundred-year clock with programmable interrupts, square wave output, and 128 bytes of nonvolatile static RAM.
The 24 pin 600mil DIP CAPHAT houses the
M48T86 silicon with a quartz crystal and a long life
lithium button cell in a single package.
B48T86/811
Complete data available on DATA-on-DISC CD-ROM or at www.st.com
SQW
E
IRQ
R/W
DS
M48T86
AS
RST
RCL
MOT
VSS
AI01640
1/2
M48T86
DIP Pin Connections
MOT
NC
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
VSS
Signal Names
24
1
23
2
22
3
21
4
20
5
19
6
M48T86
18
7
17
8
16
9
15
10
11
14
12
13
VCC
SQW
NC
RCL
NC
IRQ
RST
DS
NC
R/W
AS
E
AI01641
AD0-AD7
Multiplexed Address/Data Bus
E
Chip Enable Input
R/W
Write Enable Input
DS
Data Strobe Input
AS
Address Strobe Input
RST
Reset Input
RCL
RAM Clear Input
MOT
Bus Type Select Input
SQW
Square Wave Output
IRQ
Interrupt Request Output
VCC
Supply Voltage
VSS
Ground
Ordering Information Scheme
For a list of available options or for further information on any aspect of this device, please contact
the STMicroelectronics Sales Office nearest to you.
Warning: NC = Not Connected.
Example:
M48T86
MH
1
TR
SOIC Pin Connections
Package
NC
MOT
NC
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
VSS
VSS
1
28
27
2
3
26
4
25
24
5
23
6
22
7
M48T86
21
8
20
9
19
10
18
11
17
12
16
13
15
14
AI01642
Warning: NC = Not Connected.
2/2
NC
VCC
SQW
NC
RCL
NC
IRQ
RST
DS
NC
R/W
AS
E
NC
PC
PCDIP24
MH (2)
SOH28
Temp. Range
1
0 to 70 °C
Shipping Method for SOIC
blank
Tubes
TR
Tape & Reel
Note: 1. The SOIC package (SOH28) requires the battery/crystal
package (SNAPHAT) which is ordered separately under
the part number "M4T28-BR12SH1" in plastic tube or
"M4T28-BR12SH1TR" in Tape & Reel form.
Caution: Do not place the SNAPHAT battery/crystal package
"M4T28-BR12SH1" in conductive foam since this will
drain the lithium button-cell battery.