Datasheet

M41ST87Y, M41ST87W DC and AC parameters
Doc ID 9497 Rev 10 45/54
V
SO
Battery backup
switchover
2.5 2.5 V
R
SW
External switch
resistance on
tamper pin
500 500 Ω
1. Valid for ambient operating temperature: T
A
= –40 to 85 °C; V
CC
= 4.5 to 5.5 V or 2.7 to 3.6 V (except where noted).
2. Measured with V
OUT
and E
CON
open. Not including tamper detection current (see Table 4 on page 23).
3. RSTIN1
and RSTIN2 internally pulled-up to V
CC
through 100 kΩ resistor. WDI internally pulled-down to V
SS
through
100 kΩ resistor.
4. Outputs deselected.
5. External SRAM must match RTC supervisor chip V
CC
specification.
6. For PFO
1
and PFO
2
(if PFOD = '0'), SQW/FT (if SQWOD = '0'), and TP
CLR
pins (CMOS).
7. Conditioned output (E
CON
) can only sustain CMOS leakage current in the battery backup mode. Higher leakage currents
will reduce battery life.
8. TP
CLR
output can source –300 µA (typ) for V
BAT
= 2.9 V.
9. For IRQ
/OUT, SQW/FT (if SQWOD = '1'), PFO
1
and PFO
2
(if PFOD = '1'), RST, SDA, and F
32k
pins (open drain).
Table 17. DC characteristics (continued)
Table 18. Crystal
(1)
electrical characteristics
Symbol Parameter
(2)
Min Typ Max Units
f
O
Resonant frequency 32.768 kHz
R
S
Series resistance 65
(3)
kΩ
C
L
Load capacitance 12.5 pF
1. User supplied for the 20-lead SSOP package. STMicroelectronics recommends the KDS DT-38 (3 x 8 mm) for thru-hole, or
the KDS DMX-26S (3.2 x 8 mm) for surface-mount, tuning fork-type quartz crystals. For contact information, see Section 8:
References on page 52.
2. Load capacitors are integrated within the M41ST87. Circuit board layout considerations for the 32.768 kHz crystal of
minimum trace lengths and isolation from RF generating signals should be taken into account.
3. T
A
= –40 to 85 °C (guaranteed by design).