M48T512Y, M48T512V Clock operations
Doc ID 5747 Rev 7 13/23
One method for ascertaining how much calibration a given M48T512Y/V may require
involves setting the clock, letting it run for a month and comparing it to a known accurate
reference and recording deviation over a fixed period of time.
Calibration values, including the number of seconds lost or gained in a given period, can be
found in STMicroelectronics’ application note AN934, “TIMEKEEPER
®
calibration.” This
allows the designer to give the end user the ability to calibrate the clock as the environment
requires, even if the final product is packaged in a non-user serviceable enclosure. The
designer could provide a simple utility that accesses the calibration bits. For more
information on calibration see application note AN934, “TIMEKEEPER
®
calibration” on the
ST website.
Figure 7. Crystal accuracy across temperature
Figure 8. Calibration waveform
AI00999
–160
0 10203040506070
Frequency (ppm)
Temperature °C
80–10–20–30–40
–100
–120
–140
–40
–60
–80
20
0
–20
ΔF
= -0.038 (T - T
0
)
2
± 10%
F
ppm
C
2
T
0
= 25 °C
AI00594B
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
Obsolete Product(s) - Obsolete Product(s)
Clock operations M48T512Y, M48T512V
14/23 Doc ID 5747 Rev 7
3.5 V
CC
noise and negative going transients
I
CC
transients, including those produced by output switching, can produce voltage
fluctuations, resulting in spikes on the V
CC
bus. A ceramic bypass capacitor value of 0.1 µF
is recommended to filter these spikes.
In addition to transients that are caused by normal SRAM operation, power cycling can
generate negative voltage spikes on V
CC
that drive it to values below V
SS
by as much as
one volt. These negative spikes can cause data corruption in the SRAM while in battery
backup mode. To protect from these voltage spikes, ST recommends connecting a schottky
diode from V
CC
to V
SS
(cathode connected to V
CC
, anode to V
SS
). (Schottky diode 1N5817
is recommended for through hole and MBRS120T3 is recommended for surface mount).
Figure 9. Supply voltage protection
Caution: Negative undershoots below –0.3 V are not allowed on any pin while in the battery backup
mode.
AI02169
V
CC
0.1µF DEVICE
V
CC
V
SS
Obsolete Product(s) - Obsolete Product(s)
M48T512Y, M48T512V Maximum ratings
Doc ID 5747 Rev 7 15/23
4 Maximum ratings
Stressing the device above the ratings listed in the absolute maximum ratings table may
cause permanent damage to the device. These are stress ratings only and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Table 6. Absolute maximum ratings
Caution: Negative undershoots below –0.3 V are not allowed on any pin while in the battery backup
mode.
Symbol Parameter Value Unit
T
A
Ambient operating temperature 0 to 70 °C
T
STG
Storage temperature (V
CC
off, oscillator off) –40 to 85 °C
T
SLD
(1)(2)
1. Soldering temperature of the IC leads is to not exceed 260 °C for 10 seconds. Furthermore, the devices
shall not be exposed to IR reflow nor preheat cycles (as performed as part of wave soldering). ST
recommends the devices be hand-soldered or placed in sockets to avoid heat damage to the batteries.
2. For DIP packaged devices, ultrasonic vibrations should not be used for post-solder cleaning to avoid
damaging the crystal.
Lead solder temperature for 10 seconds 260 °C
V
IO
Input or output voltages –0.3 to V
CC
+0.3 V
V
CC
Supply voltage
M48T512Y –0.3 to 7.0 V
M48T512V –0.3 to 4.6 V
I
O
Output current 20 mA
P
D
Power dissipation 1 W
Obsolete Product(s) - Obsolete Product(s)

M48T512V-85PM1

Mfr. #:
Manufacturer:
STMicroelectronics
Description:
Real Time Clock 4 MBIT 512 Kbitx8 TIMEKEEPER
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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