1/7November 1999
M4TXX-BR12SH
TIMEKEEPER SNAPHAT (Battery & Crystal)
■ Provides Battery Backup Power for Non-Volatile
TIMEKEEPERs and Controllers in the
SNAPHAT SOIC Package
■ Removable Battery Avoids Heat Associated
with Surface Mount Process
■ Snaps Directly onto Surface-Mounted
SNAPHAT SOIC
■ Choice of Battery Capacities
– M4T28-BR12SH = 48 mAh
– M4T32-BR12SH = 120 mAh
■ Keyed Insertion to Insure Proper Assembly
■ Removable for Replacement and Proper
Disposal
■ Available in Tubes or Tape & Reel
■ For Use with the 28 and 44 pin SOIC Versions
of the TIMEKEEPER Product Families
DESCRIPTION
The M4Txx-BR12SH SNAPHAT top is a detach-
able lithium power source for ST’s non-volatile
TIMEKEEPER surface mount SOIC (MH) pack-
age (28 and 44 pin).
The SNAPHAT top contains both the battery and
crystal and is designed to be "snapped on" after
the SOIC is surface mounted on the PC board.
Thus the two piece solution avoids the battery and
crystal from having to be exposed to the high tem-
peratures of the surface mount process.
SNAPHAT (SH)
Battery & Crystal
Figure 1. Logic Diagram
AI02528
SNAPHAT
V
BAT–
V
BAT+
X1 X2
M4TXX-BR12SH
2/7
MECHANICAL INFORMATION
Electrical connection to the SOIC is made through
four pins that connect to the four press fitted sock-
ets at each end of the SOIC. Critical contact
points between the pins and sockets are gold-plat-
ed to resist oxidation. Internally, each socket con-
tains six independent contact fingers to form
redundant connections between the two compo-
nents. These sockets were designed with high
point contact force to provide the lowest possible
contact resistance. The SNAPHAT top also incor-
porates four molded-in retaining clips which hold
onto the ends of the SOIC insuring mechanical
and electrical connection even under severe me-
chanical shock and vibration. The combined SOIC
and SNAPHAT assembly can sustain shock levels
in excess of 100 g without separating. This pack-
age also passes variable frequency testing in ac-
cordance with MIL-STD-883, method 2007.2,
condition A.
Figure 2 illustrates the affect of repeated insertion
and extraction of the SNAPHAT top to the SOIC.
The force required to extract the SNAPHAT, and
then to re-insert it, reduces each time. After three
or four extractions, though, the reduction starts to
become unnoticeable, and the force required
remains at a fairly constant figure. Typically,
though, the SNAPHAT will only need to be
extracted and re-inserted once in its lifetime.
BATTERY CHARACTERISTICS
Figure 3 illustrates the lithium coin cell discharge
rate for a given load. This demonstrates the char-
Figure 2. SNAPHAT Insertion/Extraction Forces
AI02526
0
2.5
5
Force (pounds)
123
6
Number of Extractions
45
7
7.5
10
12.5
5
7.5
20
98
10
Average Insertion Force
Average Extraction Force
Table 1. Description
Parameter Value
Operating
Temperature
1 = 0 to 70 °C
6 = –40 to 85 °C
Storage
Temperature
–40 to 85 °C
Nominal Crystal
Frequency
32.768 kHz
Load Capacitance 12.5 pF
Nominal
Battery Voltage
2.8 V
Nominal
Battery Capacity
48 mAh M4T28
120 mAh M4T32
Battery Chemistry Li(CF)x
acteristically flat voltage level supplied by the bat-
tery until very near the end of its life. These
discharge levels have been greatly accelerated in
comparison to the normal, actual usage.
UL RECOGNITION
The M4Txx-BR12SH has been recognized by Un-
derwriters Laboratories under their Component
Recognition Program and carries U.L. File Num-
ber E89556.
3/7
M4TXX-BR12SH
BATTERY LIFE
For information on Data Retention Life and Battery
Storage Life, please refer to the Application Note
AN1012.
GENERAL NOTES
To remove the SNAPHAT top for replacement, a
DIP/IC extractor tool should be used.
Caution: To avoid draining battery do NOT place
SNAPHAT pins in a conductive foam.
Caution: To avoid damaging SNAPHAT sockets
do NOT wave solder SOIC.
For battery disposal information, see on the web at
www.rayovac.com.
Figure 3. Battery Discharge Rates
AI02519
0
1.0
1.5
2.0
2.5
3.0
3.5
Voltage (V)
LOAD CHARACTERISTICS Temp: 20˚C
1000 2000 3000 4000 5000 6000
Duration (hrs.)
(B)
15kΩ 30kΩ 50kΩ 100kΩ
0
1.0
1.5
2.0
2.5
3.0
3.5
Voltage (V)
LOAD CHARACTERISTICS Temp: 20˚C
200 400 600 1200 1600 1800
Duration (hrs.)
(A)
100kΩ
800 1000 1400 2000
15kΩ 30kΩ
Figure 4. DIP Extractor Tool
AI02527
