Clock operations M48T35, M48T35Y
16/28 Doc ID 2611 Rev 10
3.6 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. These transients can be reduced if
capacitors are used to store energy which stabilizes the V
CC
bus. The energy stored in the
bypass capacitors will be released as low going spikes are generated or energy will be
absorbed when overshoots occur. A bypass capacitor value of 0.1 µF (as shown in
Figure 10) is recommended in order to provide the needed filtering.
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, it is recommended to connect 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 10. Supply voltage protection
AI02169
V
CC
0.1µF DEVICE
V
CC
V
SS
M48T35, M48T35Y Maximum ratings
Doc ID 2611 Rev 10 17/28
4 Maximum ratings
Stressing the device above the rating 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.
Caution: Do NOT wave solder SOIC to avoid damaging SNAPHAT
®
sockets.
Symbol Parameter Value Unit
T
A
Ambient operating temperature
Grade 1 0 to 70 °C
Grade 6 –40 to 85 °C
T
STG
Storage temperature (V
CC
off, oscillator off) –40 to 85 °C
T
SLD
(1)(2)(3)
1. For DIP package, 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.
3. For SOH28 package, lead-free (Pb-free) lead finish: reflow at peak temperature of 260 °C (the time above
255 °C must not exceed 30 seconds).
Lead solder temperature for 10 seconds 260 °C
V
IO
Input or output voltages
M48T35 –0.3 to 7 V
M48T35Y –0.3 to 7 V
V
CC
Supply voltage
M48T35 –0.3 to 7 V
M48T35Y –0.3 to 7 V
I
O
Output current 20 mA
P
D
Power dissipation 1 W
DC and AC parameters M48T35, M48T35Y
18/28 Doc ID 2611 Rev 10
5 DC and AC parameters
This section summarizes the operating and measurement conditions, as well as the DC and
AC characteristics of the device. The parameters in the following DC and AC characteristic
tables are derived from tests performed under the measurement conditions listed in the
relevant tables. Designers should check that the operating conditions in their projects match
the measurement conditions when using the quoted parameters.
Table 7. Operating and AC measurement conditions
Note: Output Hi-Z is defined as the point where data is no longer driven.
Figure 11. AC measurement load circuit
Table 8. Capacitance
Parameter M48T35 M48T35Y Unit
Supply voltage (V
CC
) 4.75 to 5.5 4.5 to 5.5 V
Ambient operating temperature (T
A
) 0 to 70 –40 to 85 °C
Load capacitance (C
L
) 100 100 pF
Input rise and fall times 5 5ns
Input pulse voltages 0 to 3 0 to 3 V
Input and output timing ref. voltages 1.5 1.5 V
Symbol Parameter
(1)(2)
1. Effective capacitance measured with power supply at 5 V; sampled only, not 100% tested.
2. At 25 °C, f = 1 MHz.
Min Max Unit
C
IN
Input capacitance - 10 pF
C
OUT
(3)
3. Outputs deselected.
Output capacitance - 10 pF
AI01030
5V
OUT
C
L
= 100pF or 5pF
C
L
includes JIG capacitance
1.9kΩ
DEVICE
UNDER
TEST
1kΩ

M48T35Y-70PC1

Mfr. #:
Manufacturer:
STMicroelectronics
Description:
Real Time Clock 256K (32Kx8) 70ns
Lifecycle:
New from this manufacturer.
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