MSM6242B Datasheet, PDF (9/18 Pages) OKI electronic componets – DIRECT BUS CONNECTED CMOS REAL TIME CLOCK/CALENDAR

¡ Semiconductor
MSM6242B
PIN DESCRIPTION
Name
D₀
D₁
D₂
D₃
A₀
A₁
A₂
A₃
Pin No.
RS GS
14 19
13 16
12 15
11 14
4
5
5
7
6
9
7 10
ALE
3
4
WR
10 13
RD
8 11
CS₀
2
2
CS₁
15 20
STD.P 1
1
XT
16 22
XT
17 23
V_DD
18 24
GND
9 12
Description
Data Input/Output pins to be directly connected to a microcontroller bus for
reading and writing of the clock/calendar's registers and control registers. D0 = LSB
and D3 = MSB.
Address input pin for use by a microcomputer to select internal clock/calendar's
registers and control registers for Read/Write operations (See Function Table
Figure 1). Address input pins A0-A3 are used in combination with ALE for
addressing registers.
Address Latch Enable pin. This pin enables writing of address data when ALE = 1
and CSO = 0; address data is latched when ALE = 0 Microcontroller/Micro-
processors having an ALE output should connect to this pin; otherwise it should
be connected at V_DD
Writing of data is performed by this pin.
When CS₁ = 1 and CS_O = 0, D₀ ~ D₃ data is written into the register at the rising
edge of WR.
Reading of register data is accomplished using this pin. When CS₁ = 1, CS_O = 0
and RD = 0, the data of this register is output to D₀ ~ D₃. If both RD and WR are
set at 0 simaltaneously, RD is to be inhibited.
Chip Select pins. These pins enable/disable ALE, RD and WR operation. CS_O
and ALE work in combination with one another, while CS₁ work independent
with ALE. CS₁ must be connected to power failure detection as shown in Figure
18.
Output pin of N-CH OPEN DRAIN type. The output data is controlled by the
D₁ data content of C_E register. This pin has a priority to CS_O and CS₁.
Refer to Figure 9 and FUNCTIONAL DESCRIPTION OF REGISTERS.
32.768 kHz crystal is to be connected to these pins.
When an external clock of 32.768 kHz is to be used for MSM6242's oscillation
source, either CMOS output or pull-up TTL output is to be input from XT, while
XT should be left open.
Power supply pin. +2 ~ +6V power is to be applied to this pin.
Ground pin.
XT
X'tal
C₁
V_DD OR GND
C₂ XT
C1 = C2 = 15 ~ 30pF
R_FB 5MΩ
32.768 kHz
V_DD
STD.P OUTPUT
N-CH
The impedance of the crystal should be less than 30k Ω
Figure 8. Oscillator Circuit
Figure 9.
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