ACE5372

ACE5372
Low Power Real-Time Clock (RTC)
Description
The ACE5372 is a CMOS type real-time clock, which is connected to the CPU via two wires and capable
of serial transmission of clock to the CPU. The ACE5372 can generate various periodic interrupt clock
pulses lasting for long period (one month), and alarm interrupt can be made by two incorporated systems.
Since an oscillation circuit is driven at a constant voltage, it undergoes fluctuations of few voltage and
consequently offers low current consumption (TYP. 400nA @ 5V)
It also provides an oscillator halt sensing function applicable for data validation at power-on and other
occasions. The product also incorporates a time trimming circuit that adjusts the clock with higher
precision by adjusting any errors in crystal oscillator frequencies based on signals from the CPU. The
crystal oscillator may be selected from 32KHz or 32.768KHz types.
Features
•
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•
•
•
•
•
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•
•
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Lowest supply current: 400nA Typ.@5V
Connected to the CPU via only 2-wires (MAX. 100KHz)
A clock counter (counting hours. Minutes. and seconds) and a calendar counter (counting leap years,
years, months, days, and days of the week) in BCD codes.
Two system output of alarm functions
Oscillation halt sensing to judge internal data validity
Clock output of 32.768KHz (32KHz) (output controllable via a register)
Second digit adjustment by ±30 seconds
Automatic leap year recognition up to the year 2099
12-hour or 24-hour time display selectable
High precision time trimming circuit
Oscillator of 32.768KHz or 32KHz may be used
CMOS logic
Packaging Type
SOP-8
1
2
3
4
TSSOP-8
8
7
6
5
1
2
3
4
8
7
6
5
SOP-8 / TSSOP-8 Description
Function
Value
In/Out
1
INTRB
Interrupt Output B
0~12V
Out
2
SCL
Serial Clock Line
0~5.5V
In
3
SDA
Serial Data Line
0~5.5V
In/Out
4
GND
Ground Power
0V
Power
5
INTRA
Interrupt Output A
0~12V
Out
6
OSCOUT
Oscillator Circuit Output
0~1.5V
Out
7
OSCIN
Oscillator Circuit Input
0~1.5V
IN
8
VDD
Supply Voltage
1.8~5.5V Power
VER 1.4
1
ACE5372
Low Power Real-Time Clock (RTC)
Ordering information
ACE5372 XX +
H
Halogen - free
Pb - free
FM : SOP-8
TM: TSSOP-8
Block Diagram
VDD and GND
ACE5372
The VDD pin is connected to the positive power supply and GND to the ground. To prevent the possibility
of noise, when rapidly changing signal took place on ACE5372 pin, we have to place a capacitance
beside the ACE5372. One possibility is to place a bypass capacitance as close as to the ACE5372. The
capacitance capacity of C2 could be determined per user’s demand, which provides large current passing
ability between the pin and the ground.
VER 1.4
2
ACE5372
Low Power Real-Time Clock (RTC)
Bypass Capacitance
OSCIN and OSCOUT
These pins configure an oscillator circuit by connecting a crystal oscillator between the OSCIN-OSCOUT
pins. The diagram beside shows the connection method of such crystal oscillator circuit. It’s
recommended to choose the right crystal oscillator parameter referring to the supplier’s suggestion, since
it does determine the start-up reliability and oscillation stability provided by external devices. The
influence of the distributing capacitance should be considered when choosing capacitance capacity in an
oscillator circuit. To minimize output distortion, both crystal oscillator and capacitance should be installed
as close to ACE5372 pin as possible.
ACE5372
Crystal Oscillator
Connection with External
Capacitance
SCL and SDA
SCL and SDA are Serial Clock Line and Serial Data Line, relatively. SCL is used to input shift clock
pulses to synchronize data input/output to and from the SDA pin with this clock. SDA inputs and outputs
written or read data in synchronization with shift clock pulses from the SCL pin. Depend on different level
of current, separate pull-up resistance can be added to SCL and SDA on exterior circuit board.
INTRA and INTRB
INTRA and INTRB are two interrupt output ports and are both open drain outputs. When using ACE5372
a pull-up resistance must be connected with pins of INTRA and INTRB. INTRA could output periodic
interrupt pulses and alarm interrupt (ALARM-A, ALARM-B); INTRB could output 32.768KHz clock pulses
(when 32.768KHz crystal is used), periodic interrupt pulses, alarm interrupt (ALARM-B). When power is
activated from 0V, it could output 32.768kHz clock pulses (when 32.768KHz crystal is used).
Functional Descriptions
Allocation of Internal Addresses
Internal
Contents
Address
0H
Second Counter
Function
Counting and storing seconds in BCD codes
1H
Minute Counter
Counting and storing minutes in BCD codes
2H
Hour Counter
Counting and storing hours in BCD codes
3H
Day of the Week Counter
Counting and storing days of the week in BCD codes
4H
Day Counter
Counting and storing days in BCD codes
5H
Month Counter
Counting and storing months in BCD codes
6H
Year Counter
Counting and storing years in BCD codes
VER 1.4
3
ACE5372
Low Power Real-Time Clock (RTC)
7H
8H
9H
AH
BH
CH
DH
Time Trimming Register
Alarm_A (Minute
Register)
Alarm_A (Hour Register)
Alarm_A (Day of the
Week Register)
Alarm_B (Minute
Register)
Alarm_B (Hour Register)
Alarm_B (Day of the
Week Register)
EH
Control Register 1
FH
Control Register 2
Storing adjusting parameter and external select control of
crystal oscillator
Storing minutes in Timer A
Storing hours in Timer A
Storing days of the week in Timer A
Storing minutes in Timer B
Storing hours in Timer B
Storing days of the week in Timer B
Storing ring enable, interrupt output port select, and periodic
interrupt cycle select information
Storing time display select, interrupt and alarm signal,
oscillator halt sensing information
Calendar Counter
The ACE5372 can exchange from year to second (lower two bits) with CPU. When the lower two bits of
the year could be divided by 4, that year is leap year. It could automatically recognize the year between
2000 and 2099 and these data are stored separately in registers from 0H to 6H.
Control Unit
The control unit is a substantial part of the ACE5372, under which all functionalities of the whole circuit is
realized. The time display select, interrupt / alarm select and signal, output port select, as well as
oscillation halt sensing information are all sent out by the control circuit.
High Precision time Trimming function
The ACE5372 has an internal oscillation circuit capacitance CGND and CVDD so that an oscillation
circuit may be configured simply by externally connecting a crystal. The ACE5372 incorporates a time
trimming circuit (at internal address 7H) that adjusts gain or loss of the clock from the CPU up to
approx.±189ppm(±194ppm when 32.000KHz crystal is used) by approximately 3ppm steps to correct
discrepancy in oscillation frequency.
*Clock display is possible at much higher precision than conventional real-time clock while using a
crystal with broader fluctuation in precision.
* Even seasonal frequency fluctuation may be corrected by adjusting seasonal clock error.
For those systems that have temperature detection precision of clock, function may be increased by
correcting clock error according to temperature fluctuations.
VER 1.4
4
ACE5372
Low Power Real-Time Clock (RTC)
Alarm function and Periodic Interrupt
Alarm Function:
The ACE5372 has an alarm function that outputs an interrupt signal from INTRA or INTRB output pins
to the CPU when the day of the week, hour or minute corresponds to the setting. These two systems of
alarms (ALARM-A, ALARM-B), each may output interrupt signal separately at a specific time. The alarm
may be selectable between on and off for each day of the week, thus allowing outputting alarm everyday
or on a specific day of the week. The ALARM-A is output from theINTRA pin while the ALARM-B is
output from either the INTRA or theINTRB pins. Polling is possible separately for each alarm function.
Periodic Interrupt:
The ACE5372 can output periodic interrupt pulses in addition to alarm function from the INTRA
andINTRB pins. This frequency may be selected from 2Hz, 1Hz, 1/60Hz, 1/3600Hz and monthly by
controlling register (at lower 3 bits of internal address EH) output selectively.
Output waveform for periodic interrupt may be selected from regular pulse waveform (2Hz and 1Hz) and
waveforms (every second, every minute, every hour and every month) that are appropriate for CPU level
Oscillation Halt Sensing
The oscillation halt sending function uses a register (XSTP bit at internal address FH) to store oscillation
halt information. This function may be used to determine if the ACE 5372 supply power has been booted
from 0V and if it has been backed up. This function is useful for determining if clock data is valid or invalid.
Clock Output
The ACE5372 may output oscillation frequency from INTRB pin. This clock output is set for output by
default, which is set to on or off by setting the register (internal address FH bit CLEN). It can also choose
different crystal oscillator (32.768KHz or 32.000KHz) by setting the register (internal address 7H at bit
XSL), and output clock pulses with two different frequencies.
Registers
1. Clock Counter ( at internal address 0-2H )
*Time digit display ( in BCD code )
Second digits: Range from 00 to 59 and carried to minute digits when incremented from 59 to 00.
Minute digits: Range from 00 to 59 and carried to hour digits when incremented from 59 to 00.
Hour digits: See descriptions on the12/24 bit (Section 7). Carried to day and day-of-the week digits
when incremented from 11 p.m. to 12 a.m. or 23 to 00.
Any registered imaginary time should be replaced with correct time as carrying to such registered
imaginary time digits from lower-order ones cause the clock counter malfunction.
Second digit register ( at internal address 0H)
D7
D6
D5
D4
D3
D2
D1
D0
Operation
-
S40
S20
S10
S8
S4
S2
S1
Write
0
S40
S20
S10
S8
S4
S2
S1
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Default
VER 1.4
5
ACE5372
Low Power Real-Time Clock (RTC)
Minute digit register ( at internal address 1H )
D7
D6
D5
D4
D3
D2
D1
D0
Operation
-
M40
M20
M10
M8
M4
M2
M1
Write
0
M40
M20
M10
M8
M4
M2
M1
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Hour digit register ( at internal address 2H)
D7 D6
D5
D4
D3
Default
D2
D1
D0
Operation
-
-
H20 or P/A
H10
H8
H4
H2
H1
Write
0
0
H20 or P/A
H10
H8
H4
H2
H1
Read
0
0
Undefined
Undefined Undefined Undefined Undefined Undefined
Default
* Default means read value when XSTP bit is set to “I” by starting up from 0V, or supply voltage drop etc.
2. Day-of-the-week Counter ( at internal address 3H)
*Day-of-the-week digits are incremented by 1 when carried to 1-day digits.
*Day-of-the-week digits display (incremented in septimal notation):
(W4,W2,W1) = (0,0,0)→(0,0,1)→……→(1,1,0)→(0,0,0)
*The relation between days of the week and day-of-the-week digits is defined as:
Sunday=(0,0,0); Monday=(0,0,1); …… ; Saturday=(1,1,0)
(W4, W2, W1) should not be set to (1,1,1).
D7 D6 D5 D4 D3
D2
D1
D0
Operation
-
-
-
-
-
W4
W2
W1
Write
0
0
0
0
0
W4
W2
W1
Read
0
0
0
0
0
Undefined Undefined Undefined
Default
*The default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
3. Calendar Counter ( at internal address4-6H )
* The automatic calendar function provides the following calendar digit displays in BCD code and could
recognize the leap year.
Day digits: Range from 1 to 31 (for January, March, May, July, August, October, and December).
Range from 1 to 30 (for April, June, September, and November)
Range from 1 to 29 (for February in leap years)
Range from 1 to 28 (for February in ordinary years)
Month DIGITS:
Range from 1 to 12 and carried to year digits when cycled to 1. Carried to year digits when cycled
from 12 to 1.
Year digits:
Range from 00 to 99 and 00,04,08, …….,92, and 96 are counted as leap years.
Any registered imaginary time should be replaced with correct time as carrying to such registered
imaginary
time digits from lower-order ones cause the clock counter malfunction.
VER 1.4
6
ACE5372
Low Power Real-Time Clock (RTC)
Day digit register ( at internal address 4H )
D7 D6
D5
D4
D3
D2
D1
D0
Operation
-
-
D20
D10
D8
D4
D2
D1
Write
0
0
D20
D10
D8
D4
D2
D1
Read
0
0
Undefined Undefined Undefined Undefined Undefined Undefined
Default
*Default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
Mouth digit register ( at internal address 5H )
D7 D6 D5
D4
D3
D2
D1
D0
Operation
-
-
-
MO10
MO8
MO4
MO2
MO1
Write
0
0
0
MO10
MO8
MO4
MO4
MO1
Read
0
0
0
Undefined Undefined Undefined Undefined Undefined
Default
*Default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
Year digit register ( at internal address 6H )
D7
D6
D5
D4
D3
D2
D1
D0
Operation
Y80
Y40
Y20
Y10
Y8
Y4
Y2
Y1
Write
Y80
Y40
Y20
Y10
Y8
Y4
Y2
Y1
Read
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Default
*Default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
4. Time Trimming Register ( at internal address 7H )
D7
D6 D5 D4 D3 D2 D1 D0 Operation
XSL_
F6
F5
F4
F3
F2
F1
F0
Write
XSL_
F6
F5
F4
F3
F2
F1
F0
Read
0
0
0
0
0
0
0
0
Default
*Default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
XSL bit
The XSL bit is used to select a crystal oscillator.Set the XSL to“0”(default) to use 32.768KHz；Set XSL
to“1”to use 32KHz.
F6 to F0
The time trimming circuit adjust one second count based on this readings when second digit is 00,20, or
40 seconds. Normally, counting up to seconds is made once per 32,768 of clock pulse (or 32,000 when
32.000KHz crystal is used) generated by the oscillator. Setting data to this register activates the time
trimming circuit. Register counts will be incremented as (( F5,F4,F3,F2,F1,F0)-1) x2 when F6 is set to “0”.
Register counts will be incremented as ((F5, F4, F3, F2, F1, F0)-1) x2 when F6 is set to “0”.
Register counts will be decremented as ((F5, F4, F3, F2, F1, F0)+1) x2 when F6 is set to “1”.
Counts will not change when (F6, F5, F4, F3, F2, F1, F0) are set to (*, 0, 0, 0, 0, 0, *).
VER 1.4
7
ACE5372
Low Power Real-Time Clock (RTC)
For example, when 32.768KHz crystal is used. When (F6, F5, F4, F3, F2, F1, F0) are set to (0,1, 0, 1,
0, 0,1), counts will change as: 32768+（41-1）*2=32848(clock will be delayed) when second digit is 00, 20,
or 40.When (F6, F5, F4, F3, F2, F1, F0) are set to (0, 0, 0, 0, 0, 0, 1), counts will remain 32,768 without
changing when second digit is 00, 20, or 40. When (F6, F5, F4, F3, F2, F1, F0) are set to (1,1,0,1,0,0,1),
counts will change as: 32768+（-23+1）*2=32724 (clock will be advanced) when second digit is 00, 20, or
40.
Adding 2 clock pulses every 20 seconds: 2/ （ 32768*20 ） =3.051ppm (or 3.125ppm when
32.000KHZcrystal is used), delays the clock by approx. 3ppm. Likewise, decrementing 2 clock pulses
advances the clock by 3ppm. Thus the clock may be adjusted to the precision of±1.5ppm. Note that the
time trimming function only adjusts clock timing and oscillation frequency but 32.768KHz clock output is
not adjusted.
5. Alarm Register (Alarm-A : internal address 8-AH; Alarm-B : internal address B-DH)
Alarm-A minute register (at internal address 8H)
D7
D6
D5
D4
D3
D2
D1
D0
Operation
-
AM40
AM20
AM10
AM8
AM4
AM2
AM1
Write
0
AM40
AM20
AM10
AM8
AM4
AM2
AM1
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Alarm-B minute register (at internal address BH)
D7
D6
D5
D4
D3
Default
D2
D1
D0
Operation
-
BM40
BM20
BM10
BM8
BM4
BM2
BM1
Write
0
BM40
BM10
BM10
BM8
BM4
BM2
BM1
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Alarm-A hour register (at internal address 9H)
D7 D6
D5
D4
D3
Default
D2
D1
D0
Operation
-
-
AH20,AP/A
AH10
AH8
AH4
AH2
AH1
Write
0
-
AH20,AP/A
AH10
AH8
AH4
AH2
AH1
Read
0
0
Undefined
Undefined Undefined Undefined Undefined Undefined
Alarm-B hour register (at internal address CH)
D7 D6
D5
D4
D3
Default
D2
D1
D0
Operation
-
-
BH20,BP/A
BH10
BH8
BH4
BH2
BH1
Write
0
0
BH20,BP/A
BH10
BH8
BH4
BH2
BH1
Read
0
0
Undefined
Undefined Undefined Undefined Undefined Undefined
Default
VER 1.4
8
ACE5372
Low Power Real-Time Clock (RTC)
Alarm-A day-of-week register (at internal address AH)
D7
D6
D5
D4
D3
D2
D1
D0
Operation
-
AW6
AW5
AW4
AW3
AW2
AW1
AW0
Write
0
AW6
AW5
AW4
AW3
AW2
AW1
AW0
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Alarm-B day-of-the-week register (at internal address DH)
D7
D6
D5
D4
D3
D2
Default
D1
D0
Operation
-
BW6
BW5
BW4
BW3
BW2
BW1
BW0
Write
0
BW6
BW5
BW4
BW3
BW2
BW1
BW0
Read
0
Undefined Undefined Undefined Undefined Undefined Undefined Undefined
Default
*Default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
* ALARM-A, ALARM-B hour register D5 is set to “0” for AM and “1” for PM in the 12-hour display system.
The register D5 indicates 10 digit of hour digit in 24-hour display system.
* To activate alarm operation, any imaginary alarm time setting should not be left to avoid un-matching.
* In hour digit display midnight is et to “12”, noon is set to “32” in 12-hour display system.
* AW0 to AW6 (BW0 to BW6) correspond to the day-of-the-week counter being set at (0,0,0) to (1,1,0).
No alarm pulses are output when all of AW0 to AW6 (BW0 to BW6) are set to “0”
Example of Alarm Time Settings
Day-of-the-week
12-hour system
24-hour system
Alarm Time
Settings
Sun Mon Tue Wed Thu Fri Sat 10H 1H 10M 1M 10H 1H 10M 1M
00:00AM
1
1
1
1
1
1
1
1
2
0
0
0
0
0
0
every day
05:27AM
1
1
1
1
1
1
1
0
5
2
7
0
5
2
7
every day
11:59AM
1
1
1
1
1
1
1
1
1
5
9
1
1
5
9
every day
00:00PM on
0
1
1
1
1
1
0
3
2
0
0
1
2
0
0
Mon thru Fri
05:56PM on
0
0
0
1
0
0
0
2
5
5
6
1
7
5
6
Wed
11:59PM on
0
0
1
0
1
0
1
3
1
5
9
2
3
5
9
Tue, Thu, and
Sat
VER 1.4
9
ACE5372
Low Power Real-Time Clock (RTC)
6. Control Register 1 (at internal address EH)
D7
D6
D5 D4
D3
D2
D1
D0
Operation
AALE BALE SL2 SL1 TEST CT2 CT1 CT0
Write
AALE BALE SL2 SL1 TEST CT2 CT1 CT0
Read
0
0
0
0
0
0
0
0
Default
*The default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
AALE , BALE
ALARM-A, ALARM-B enable bits
AALE，BALE
Description
Operation
0
ALARM-A，ALARM-B correspondence action invalid
Default
1
ALARM-A，ALARM-B correspondence action valid
L2, SL1
Interrupt output select bits
SL2 SL1
Description
Operation
Outputs ALARM-A, ALARM-B, INT to the INTRA. Outputs 32K clock pulses to
0
0
Default
the INTRB.
Outputs ALARM-A, INT to the INTRA. Outputs 32K clock pulses, ALARM-B to
0
1
the INTRB.
Outputs ALARM-A, ALARM-B to the INTRA. Outputs 32K clock pulses, INT to
1
0
the INTRB.
Outputs ALARM-A to the INTRA. Outputs 32K clock pulses, ALARM-B, INT to
1
1
the INTRB.
By setting SL1 and SL2 bits, two alarm pulses (ALARM-A, ALARM-B), periodic interrupt output (INT),
32K clock pulses may be output to the INTRA or INTRB pins selectively.
TEST
ACE5372 Test bit
Description
TEST
0
Ordinary operation mode
1
Test mode
Operation
Default
VER 1.4
10
ACE5372
Low Power Real-Time Clock (RTC)
CT2, CT1, CT0
Periodic interrupt cycle select bit
Description
CT2 CT1 CT0
0
0
0
Wave Form
Mode
-
0
0
1
-
INTRA（INTRB）at low level
0
1
0
Pulse Mode
2Hz（Duty 50%）
0
1
1
Pulse Mode
1Hz（Duty 50%）
1
0
0
Level Mode
Every second（synchronized with second count up）
1
0
1
Level Mode
Every minute（00 second of every minute）
1
1
0
Level Mode
Every hour（00 minute 00 second of every hour）
Cycle and INTRA（INTRB）Falling Timing
INTRA（INTRB）at high level
Every month（the 1st day 00 A.M. 00 minute 00 second of every
1
1
1
Level Mode
month）
1) Pulse mode: Outputs 2Hz, 1Hz clock pulses. For relationships with counting up of seconds see the
diagram below.
In the 2Hz clock pulse mode, 0.496s clock pulses and 0.504s clock pulses are output alternatively.
Duty cycle for 1Hz clock pulses becomes 50.4%.
2) Level mode: One second, one minute or one month may be selected for an interrupt cycle. Counting up
of seconds is matched with falling edge of interrupt output.
3) When the time trimming circuit is used, periodic interrupt cycle changes every 20 seconds.
Pulse mode:“L” duration of output pulses may change in the maximum range of ±3.784ms (±3.875ms
when 32KHz crystal is used).
For example, Duty will be 50±0.3784% (or 50±0.3875% when 32KHz crystal is used) at 1Hz.
Level Mode: Frequency is one second may change in the maximum range of ±3.784ms (±3.875ms
when 32KHz crystal is used).
Relation Between Mode Waveforms and CRFG Bit

Pulse mode
VER 1.4
11
ACE5372
Low Power Real-Time Clock (RTC)

Level mode
7. Control Register 2 ( at internal address FH )
D7 D6
D5
D4
D3
D2
-
-
12_/24
0
0
12_/24
0
0
Undefined
ADJ
D1
D0
Operation
CLEN_ CTFG AAFG BAFG
Write
XSTP CLEN_ CTFG AAFG BAFG
Read
1
0
0
0
0
Default
*The default means read value when XSTP bit is set to “1” by starting up from 0V, or supply voltage drop, etc.
12/24
12/24-hour Time Display System Selection bit
12/24
Description
0
12-hour time display system
1
24-hour time display system
Being set this bit at “0” indicates 12-hour display system while “1” indicates 24-hour system.
Time Display Digit Table
24-hour time display
system
00
12-hour time display
system
12(AM12)
24-hour time display
system
12
12-hour time display
system
32(PM12)
01
01(AM1)
13
21(PM1)
02
02(AM2)
14
22(PM2)
03
03(AM3)
15
23(PM3)
04
04(AM4)
16
24(PM4)
05
05(AM5)
17
25(PM5)
06
06(AM6)
18
26(PM6)
07
07(AM7)
19
27(PM7)
08
08(AM8)
20
28(PM8)
09
09(AM9)
21
29(PM9)
10
10(AM10)
22
30(PM10)
11
11(AM11)
23
31(PM11)
VER 1.4
12
ACE5372
Low Power Real-Time Clock (RTC)
Either the 12-hour or 24-hour time display system should be selected before writing time data.
ADJ
±30 Second Adjust Bit
ADJ
Description
0
Ordinary operation
1
Second digit adjustment
* The following operations are performed by setting the second ADJ bit to 1
1) For second digits ranging from “00” to “29” seconds：Time counters smaller than seconds are reset
and second digits are set to “00”.
2) For second digits ranging from “30” to “59” seconds: Time counters smaller than seconds are reset
and second digits are set to “00”. Minute digits are incremented by 1.
* Second digits are adjusted within 122us(within 125us: when 32KHz crystal is used) from writing
operation to ADJ.
The ADJ bit is for write only and allows no read operation.
XSTP
Oscillator Halt Sending Bit
XSTP
Description
0
Ordinary oscillation
1
Oscillator halt sensing
Operation
default
The XSTP bit senses the oscillator halt.
* When oscillation is halted after initial power on from 0V or drop in supply voltage the bit is set to “1” and
which remains to be “1” after it is restarted. This bit may be used to judge validity of clock and calendar
count data after power on or supply voltage drop.
* When this bit is set to “1”, XSL，F6 to F0，CT2，CT1，CT0，AALE，BALE，SL2，SL1，CLEN and
TEST bits are reset to “0”. INTRA will stop output and the INTRB will output 32KHz clock pulses.
The XSTP bit is set to “0” by setting the control register 2 (address FH) during ordinary oscillation.
CLEN
32KHz Clock Output Bit
CLEN
Description
0
32KHz clock output enabled
1
32KHz clock output disabled
Operation
Default
By setting this bit to “0”, output of clock pulses of the same frequency as the crystal oscillator is enabled.
CTFG
Periodic Interrupt Flag Bit
CTFG
Description
0
Periodic interrupt output=OFF
1
Periodic interrupt output=ON
Operation
Default
VER 1.4
13
ACE5372
Low Power Real-Time Clock (RTC)
This bit is set to “1” when periodic interrupt pulses are output (INTRA or INTRB= “L”).
The CTFG bit may be set only to “0” in the interrupt level mode. Setting this bit to “0” sets either
theINTRA or theINTRB to OFF (“H”). When this bit is set to “1” nothing happens.
AAFG, BAFG
ALARM-A, ALARM-B Flag Bit
ALARM-A，ALARM-B
0
Description
Operation
Unmatched alarm register with clock counter
Default
1
Matched alarm register with clock counter
* The alarm interruption is enabled only when the AALE, BALE bits are set to “1”. This bit turns to “1”
when matched time is sensed for each alarm.
* The AAFG, BAFG bit may be set only to “0”. Setting this bit to “0” sets either the INTRA or the
 INTRB to the OFF “H”. When this bit is set to “1” nothing happens.
When the AALE, BALE bit is set to “0”, alarm operation is disabled and “0” is read from the AAFG, BAFG
bit.
Output Relationships Between AAFG（BAFG）Bit and INTRA（INTRB）
VER 1.4
14
ACE5372
Low Power Real-Time Clock (RTC)
Transmission System of Interface
Communication protocol determines: circuits in the equipment which sends data through SDA bus are
regarded as emitters, contrarily, circuits in the equipment which receives data through SDA bus are
regarded as receivers. Master equipment and master circuit control data transmission; Slave circuit is
controlled.
Typical System Bus Structure
Data Validity Protocol
Data transmission protocol determines: Transmit one bit data in every clock cycle. SDA must be kept at
a certain state while SCL is at the “H” state as shown below during data transmission.
Start and stop conditions
The SCL and SDA pins are at the “H” level when no data transmission is made. Changing the SDA from
“H” to “L” when the SCL and the SDA are “H” activates the start condition and access is started. Changing
the SDA from “L” to “H” when the SCL is “H” activates stop condition and accessing stopped.
Start and stop conditions
VER 1.4
15
ACE5372
Low Power Real-Time Clock (RTC)
As the arrival of the start condition, master emitter must send out an address command bit, which
includes slave address and R/W model; When a certain receiver in bus is chosen, it will send ACK signal
and SDA changes into low voltage. ACK signal indicates the success of data transmission. When SCL
clock drops, emitter sends continuously 8 bits and releases the data bus (SDA changes into high voltage).
The slave address
The high effective 7 bits (bit7---bit1) in the address byte are defined as device type id. In ACE5372,
these 7 bits are 0110010. The lowest bit0 is defined as R/W model. When this bit is “1”, it is read model,
while “0” is write model.
The slave address
BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
0
1
1
0
0
1
0
R/W
BIT7-BIT1 : The slave address of the ACE5372 is defined as 0110010
BIT0 : R/W definition
“1” is read model
“0” is write model
Data transmission format in the Interface Communication
Interface generates no Chip Enable signals. In place of it each device has a 7bit slave address
allocated. The first 1byte is allocated to this 7bit of slave address and to the command (R/W) for which
data transmission direction is designated b the data transmission thereafter.
The slave address of the ACE5372 is specified at (0110010).
At the end of data transmission/receiving stop condition is generated to complete transmission. However,
if start condition is generated without generating stop condition, repeated start condition is met and
transmission/receiving data may be continued by setting the slave address again. Use this procedures
when the transmission direction needs t be changed during one transmission.
Data is written into the slave from the master
S 0 1 1 0 0 1 0
0
A Data A Data A P
Slave address
Write
VER 1.4
16
ACE5372
Low Power Real-Time Clock (RTC)
When data is read from the slave immediately after 7bit addressing from the master
S
0
1 1 0 0 1 0
1
A Data A Data A_ P
Slave address
Read
When the transmission direction is to be changed during transmission
Data Transmission Write Format in the ACE5372
A) First send 7 address bit(0110010), the eighth bit is write command “0”.
B) When the ninth bit is ACK signal, ACE5372 is under writing condition.
C)In the following byte, the high 4 bits are determined as internal address in ACE5372(0H-FH), the low 4
bits are transmission model.
D)After another bit’s ACK signal, it starts writing data normally.
E)After writing 1 byte data, there will be 1 bit ACK signal and then writing data in next 1 byte starts. Only
when there is a stop signal in the bit after ACK signal, can the writing operation be stopped.
Example of data writing (When writing to internal address 4H to 5H)
CPU to ACE5372
Start condition
ACE5372 to CPU
Acknowledge signal
Stop condition
VER 1.4
17
ACE5372
Low Power Real-Time Clock (RTC)
Data Transmission Read Format in the ACE5372
The ACE5372 allows the following three readout methods of data from an internal register.
I) The first method to reading data from the named internal address
A)The first three steps are the same as write model
B)After one bit ACK signal, a new start signal will be produced to change the direction of data
transmission in INTERFACE connection.
C)Then send 7 address bit(0110010), the eighth bit command is “1”, ACE5372 is under data reading
condition.
D) After another bit’s ACK signal, it starts reading data normally.
E)When a byte data is read and CPU sends 1 bit ACK signal, a next byte data can be read. Only when
the 1 bit ACK signal which is sent by CPU is high voltage, can the reading operation be stopped and
then CPU sends stop signals.
Example 1 of data read (when data is read from 7H to 9H)
Inform ACE5372 to stop read
CPU to ACE5372
Start signal
ACE5372 to CPU
Stop signal
Acknowledge signal
Repeat Start signal
VER 1.4
18
ACE5372
Low Power Real-Time Clock (RTC)
II) The second method to reading data from the internal register is to start immediately after writing to the
internal address pointer and the transmission format register. Set 4h to the transmission format register
when this method is used.
Example 2 of data read (when data is read from internal address Dh to 0h)
Inform ACE5372 to stop read
CPU to ACE5372
Start signal
ACE5372 to CPU
Stop signal
Acknowledge signal
Repeat Start signal
III) The third method to reading data from the internal register is to start reading immediately after writing
to the slave address(0110010) and the (R/W) bit. Since the internal address pointer is set to Fh by
default , this method is only effective when reading is started from the internal address Fh.
Example 3 of data read (when data is read from internal address Fh to 3h).
CPU to ACE5372
Start signal
ACE5372 to CPU
Stop signal
Acknowledge signal
Repeat Start signal
Data Transmission Under Special Condition
The ACE5372 hold the clock tentatively for duration from start condition to stop condition to avoid invalid
read or write clock on carrying clock. To prevent invalid read or write clock shall be made during one
transmission operation. When 0.5 to 1.0 seconds elapses after start condition any access to the ACE5372
is automatically released to release tentative hold of the clock and access from the CPU is forced to be
terminated (automatic resume function from the interface).
Also a second start condition after the first condition and before the stop condition is regarded as the
“repeated start condition”. Therefore, when 0.5 to 1.0 seconds passed after the first start condition,
access to the ACE5372 is automatically released.
VER 1.4
19
ACE5372
Low Power Real-Time Clock (RTC)
The user shall always be able to access the real-time clock as long as the following two conditions are
met.
1) No stop condition shall be generated until clock read/write is started and completed.
2) One cycle read/write operation shall be completed within 0.5 seconds.
Bad example of reading from seconds to hours (invalid read)
(Start condition) → (Read of seconds) → (Read of minutes) → (Stop condition) → (Start condition) →
(Read of hour) → (Stop condition)
Assuming read was started at 09:59:59PM, and while reading seconds and minutes the time
advanced to 10:00:00 PM. At this time second digit is hold so the read as 59:59. ACE5372
confirms (Stop condition) and carry second digit being hold and the time changes to 10:00:00 PM.
Then, when the hour digit is read, it changes to 10. The wrong results of 10:59:59 will be read.
Configuration of Oscillating Circuit and Time Trimming Circuit
a)In general crystal oscillators are classified by their central frequency of CL (load capacitance) and
available further grouped in several ranks as ±10，±20 and ±50ppm of fluctuations in precision.
b)The fluctuation of IC circuit frequency is ±5~10ppm at room temperature.
c)Here, the clock accuracy at room temperature varies along with the variation of the characteristic of
crystal oscillator.
Configuration of Oscillating Circuit
Because the adjustment of crystal oscillator frequency is also the adjustment of clock frequency, so the
former adjustment can be done through CIN & COUT on the both sides of crystal.
ACE5372 clock cooperates with CIN & COUT, so oscillator frequency can be referred to crystal CL.
General, relation between CL and CIN or COUT is as follows：
Cl =
Cin * Cout
+ Cs
Cin + Cout
CS：Board floating capacitance
If crystal oscillator frequency is on the higher side, the CL should be decreased, contrarily, the CL should
be increased.
VER 1.4
20
ACE5372
Low Power Real-Time Clock (RTC)
According to this standard, the best CL is chosen to adjust frequency and clock frequency. For example:
if the frequency is on the higher side, it can be lowed by attaching a CGOUT capacitor.
ACE5372
*CGOUT＝0~15pF
Time Trimming Circuit
Using the time trimming circuit gain or lose of clock may be adjusted with high precision by changing
clock pulses for one second every 20 seconds.
1.When oscillation frequency *1 > target frequency*2（clock gain）
Adjustment amount*3
=
(OscilationFrequency − T arg etFrequency + 0.1)
OscillationFrequency * 2
(T arg etFrequency * 20)
= (Oscillation frequency – Target frequency) x 10 +1
*1) Oscillation frequency: Clock frequency output from the INTRB pin
*2) Target frequency: TYP. 32.768KHz to 32.000KHz
*3) Adjustment amount: A value to be set finally to F6 to F0 bits. This value is expressed in 7 bit binary
digits with sign bit (two’s compliment).
2.When oscillation frequency = target frequency (no clock gain or loss)
Set the adjustment value to 0 or +1, or –64, or –63 to disable adjustment.
3.When oscillation frequency < target frequency (clock losses)
Adjustment amount
(OscilationFrequency − T arg etFrequency )
OscillationFrequency * 2
(T arg etFrequency * 20)
=
=
(Oscillation frequency – Target frequency) x 10
VER 1.4
21
ACE5372
Low Power Real-Time Clock (RTC)
Example of Calculations
1) When oscillation frequency = 32770kHz; target frequency = 32768kHz
Adjustment value = （32770-32768+0.1）/(32770*2/(32768*20))
=(32770-32768)*10+1=21
Set （F6，F5，F4，F3，F2，F1，F0）=（0，0，1，0，1，0，1）
2) When oscillation frequency =32762kHz; target frequency = 32768kHz
Adjustment value =（32762-32768）/(32762*2/(32768*20))
= (32762-32768)*10=-60
To express –60 in 7bi binary digits with sign bit ( two’s compliment)
Subtract 60(3Ch) from 128(80h) in the above case, 80h-3Ch=44h
Thus set （F6，F5，F4，F3，F2，F1，F0）=（1，0，0，0，1，0，0）
After adjustment, adjustment error against the target frequency will the approx. ±1.5ppm at a room
temperature.
Notice:
1) Clock frequency output from theINTRB pin will change after adjustment by the clock adjustment circuit.
2) Adjustment range:
A)When oscillation frequency is higher than target frequency, the range of adjustment values is （F6，F5，F4，F3，F2，F1，
F0）=（0，0，0，0，0，0，1）to (0，1，1，1，1，1，1) and actual adjustable amount shall be -3.05ppm to –189.2ppm (-3.125ppm
to 193.7ppm for 32000Hz crystal).
B) When oscillation frequency is lower than target frequency, the range of adjustment values is （F6，F5，F4，F3，F2，F1，
F0）=（1，1，1，1，1，1，1）to（1，0，0，0，0，1，0）and actual adjustable amount shall be 3.05ppm to 189.2ppm (3.125ppm
to 193.7ppm for 32000Hz crystal)
Output Waveforms
The following three output waveforms can be output from the INTRA (INTRB) pin.
1）Alarm interrupt
When a registered time for alarm (such as day-of-the-week, hour or minute) coincide with calendar
counter (such as day-of-the-week, hour or minute) interrupt to the CPU are requested with the output pin
being on “L”. Alarm interrupt consists of Alarm_A and Alarm_B, both have equivalent functions.
2）Periodic interrupt
Outputs an output waveform selected by setting the periodic interrupt frequency select bit. Waveforms
include pulse mode and level mode.
3）32KHz clock output
Clock pulses generated in the oscillation circuit are output as they are.
VER 1.4
22
ACE5372
Low Power Real-Time Clock (RTC)
Control of theINTRA (INTRB) Output (flag bit, enable bit, interrupt output select bit)
Of the three output wave forms listed above, interrupt output conditions may be set by setting the flag bit
that monitors output state on the register, the enable bit that enables an output wave form and the output
select bit that selects either INTRA or INTRB to be output.
Interrupt output select bit （SL2，SL1）
(D5，D4 at EH)
Flag bit
Enable bit
（0，0） （0，1） （1，0） （1，1）
AAFG
AALE
Alarm_A
(D1 at
INTRA INTRA INTRA INTRA
(D7 at EH)
FH)
BAFG
BALE
Alarm_B
(D0 at
INTRA INTRB INTRA INTRB
(D6 at EH)
FH)
CTFG
Disabled at
Periodic interrupt
(D2 at
INTRA INTRA INTRB INTRB
CT2=CT1=CT0=0
FH)
(D2 to D0 at EH)
CLEN
32KHz clock
NO
INTRB INTRB INTRB INTRB
output
(D3 at FH)
* When power ON (XSTP=1) since AALE=BALE=CT2=CT1=CT0=CLEN=SL2=SL1=0, INTRA=OFF
(“H”) and 32KHz clock pulses are output from the INTRB pin.
When more than one output waveforms are output from a single output pin, the output will have OR
wave form of negative logic of both.
Alarm Interrupt
For setting an alarm time, designated time such as day-of-the-week, hour or minute should be set to the
alarm registers being AALE（BALE）bit to 0. After that set the AALE（BALE） bit to 1, from this moment
onward when such registered alarm time coincide the value of calendar counter theINTRA (INTRB)
comes down to “L” (ON). The INTRA (INTRB) output can be controlled by operating to the AALE (BALE)
and AAFG (BAFG) bits.
VER 1.4
23
ACE5372
Low Power Real-Time Clock (RTC)
Periodic (Clock) Interrupt
The INTRA (INTRB) pin output, the periodic interrupt cycle select bits (CT2, CT1, CT0) and the
interrupt output select bits (SL2, SL1) can be used to interrupt the CPU in a certain cycle. The periodic
interrupt cycle select bits can be used to select either one of two interrupt output modes: the pulse mode
and the level mode.
CT2 CT1 CT0
Description
Wave Form Mode
Cycle and INTRA(INTRB) Falling Timing
0
0
0
-
INTRA（INTRB）OFF (Default)
0
0
1
-
INTRA（INTRB）fixed at “L”
0
1
0
Pulse Mode
2Hz (Duty 50%)
0
1
1
Pulse Mode
1Hz (Duty 50%)
1
0
0
Level Mode
Every second (coincident with second count-up)
1
0
1
Level Mode
Every minute (00 second of every minute)
1
1
0
Level Mode
Every hour (00minute 00second of every hour)
1
1
1
Level Mode
Every month (1st day, 00:00:00 a.m.of every month)
1) Pulse mode: Output 2Hz, 1Hz clock pulses. For relationships with counting up of seconds see the
diagram below.
In the 2Hz clock pulse mode, 0.496s clock pulses and 0.504s clock pulse are output
alternatively.
Duty cycle for 1Hz clock pulses becomes 50.4%.
2) Level mode: One second, one minute one month may be selected for an interrupt cycle.
Counting up of seconds is matched with falling edge of interrupt output.
3) When the time trimming circuit is used, periodic interrupt cycle changes every 20 seconds.
Pulse mode: “L” duration of output pulses may change in the maximum range of ±3.784ms
(±3.875ms when 32KHz crystal is used)
VER 1.4
24
ACE5372
Low Power Real-Time Clock (RTC)
For example, Duty will be 50±0.3784% (or 50±0.3875% when 32KHz crystal is used)at 1Hz.
Level mode: Frequency in one second may change in the maximum range of ±3.784ms
(±3.875ms when 32KHz crystal is used).
Relation Between Mode Waveforms and CRFG Bit

Pulse mode

Level mode
32Khz Clock Output
The crystal oscillator can generate clock pulses of 32KHz from the INTRB pin. The pin is changed to
“H” by setting the CLEN bit to “1”.
* 32KHz clock pulse output will not be affected from settings in the clock adjustment register.
When power ON (XSTP=1), 32KHz clock pulses are output from the INTRB pin.
Oscillator Halt Sensing
Oscillation halt can be sensed through monitoring the XSTP bit with preceding setting of the XSTP bit to
“0” by writing data to the control register 2.Upon oscillator halt sending, the XSTP bit is switched from 0 to
1. This function can be applied to judge clock data validity. When the XSTP bit is “1”, XSL,
F6 to F0, CT2, CT1, CT0, AALE, BALE, SL2, SL1, CLEN and TEST bits are reset to “0”.
*1）The XSTP bit is set to “1” upon power-on from 0V. Note that any instantaneous power disconnection
may cause operation failure.
*2）Once oscillation halt has been sensed, the XSTP bit is held at “1” even if oscillation is restarted.
Ensure error-free oscillation half sensing by preventing the following events:
1) Instantaneous disconnection of VDD
2) Condensation on the crystal oscillator
3) Generation of noise on the PCB in the crystal oscillator
4) Application of voltage exceeding prescribed maximum ratings to the individual pins of the IC
VER 1.4
25
ACE5372
Low Power Real-Time Clock (RTC)
DC Characteristics
TOPT=-40℃ to +85℃, GND=0V, VDD=3.6V, fOSC=32,768Hz or 32,000Hz
Symbol
Item
Pin name
VIH
“H” Input Voltage
SCL, SDA
VIL
“L” Input Voltage
SCL, SDA
INTRA,
INTRB
IOL1
“L” Output Current
IOL2
IILK
VDD
IOZ
IDD
SDA
Input Leakage Current
SCL
Operating Voltage
VDD
GND
Counting Voltage
Output Off State Leakage
Current
Standby Current
Conditions
Min.
Typ.
Max.
Unit
0.8VDD
6.0
V
-0.3
0.3VDD
V
VOL1=0.4V
1
mA
VOL2=0.6V
VI=6VorGND
VDD=6V
7
mA
SDA, INTRA, VO=6VorGND
INTRB
VDD=6V
VDD=5V,
VDD
TOPT=25℃
SCL,SDA=5V
-1
1
uA
1.8
5.5
V
1.2
5.5
V
-1
1
uA
0.4
uA
AC Characteristics
Characteristics Parameter
TA= -40℃ to +85℃，VDD =4.5V to 5.5V
Symbol
Item
Conditions
fSCL
SCL Clock Frequency
0
tLOW
SCL Clock “L” Time
4.7
us
tHIGH
SCL Clock “H” Time
5
us
tBUF
Bus release Time
4.7
us
tSU:STA
Start Condition Setup Time
4.7
us
tSU:STO
Stop Condition Setup Time
4.7
us
tHD:STA
Start Condition Hold Time
4
us
tHD:STO
Stop Condition Hold Time
4
us
tSU:DAT
Data Setup Time
250
ns
tHD:DAT
Data input Hold Time
0
ns
THD
Data output Hold Time
0
ns
tAA
clock output
tR
before next data is transmitted
SCL negedge to SDA data
changes
SCL negedge to SDA data
availed
Min. Max. Unit
0.3
100
KHz
3.5
us
Rising Time of SCL and SDA (Input)
1
us
tF
Falling Time of SCL and SDA (Input)
300
ns
tI
Spike width that can be removed with
100
ns
VER 1.4
26
ACE5372
Low Power Real-Time Clock (RTC)
input filter
Absolute Maximum Ratings
Symbol
Item
Conditions
Ratings
Unit
VDD
Supply Voltage
-0.3 to +7.0
V
VI
Input Voltage
SCL，SDA
-0.3 to +7.0
V
VO1
Output Voltage 1
SDA
-0.3 to +7.0
V
VO2
Output Voltage 2
INTRA, INTRB -0.3 to +12.0
V
TOPT
Operating Temperature
-40 to +85
℃
TSTG
Storage Temperature
-55 to +125
℃
Typical Applications
Example of Circuit
ACE5372
ACE5372
(A)
(B)
1.Mount the high-and low-frequency by-pass capacitors C0 and C1 (TYP. C1=10uF, C2=0.1uF)
2.The typical volume of pull-up resistance R0~R3 is 10KΩ
3.BATT and VCC’s Voltage: VBATT≤VVCC
4.Connect the pull-up resistor of the INTRA pin or the INTRB pin to two different positions depending
battery back-up:
VER 1.4
27
ACE5372
Low Power Real-Time Clock (RTC)
A. when the spare battery supplies power, INTRA (B) is not used.
B. when the spare battery supplies power, INTRA (B) is used.
Example of Interface Circuit to the CPU
ACE5372
VER 1.4
28
ACE5372
Low Power Real-Time Clock (RTC)
Package Information
SOP-8
Symbol
mm
Min
Inches
Typ. Max
Min
Typ.
Max
A
1.35
-
1.75 0.053
-
0.069
A1
0.10
-
0.25 0.004
-
0.010
B
0.33
-
0.51 0.013
-
0.020
C
0.19
-
0.25 0.007
-
0.010
D
4.80
-
5.00 0.189
-
0.197
ddd
-
-
0.10
-
0.004
E
3.80
-
4.00 0.150
-
0.157
e
-
1.27
0.050
-
H
5.80
-
6.20 0.228
-
0.244
h
0.25
-
0.50 0.010
-
0.020
L
0.40
-
0.90 0.016
-
0.035
α
0o
-
-
8o
-
8o
-
0o
VER 1.4
29
ACE5372
Low Power Real-Time Clock (RTC)
Package Information
TSSOP-8
Dimensions (mm are the original dimensions)
Unit
A
max.
mm
1.10
Unit
mm
A1
A2
A3
Bp
C
D(1)
E(2)
e
0.15 0.95
0.32 0.25 3.10 4.60
0.25
0.65
0.05 0.80
0.12 0.10 2.90 4.20
L
Lp
v
w
y
Z(1)
θ
HE
6.70
0.80
0.70 100
0.94
0.1 0.1 0.1
6.10
0.20
0.35 00
Notes:
1.Plastic or metal protrusions of 0.15mm maximum per side are not included
2.Plastic or metal protrusions of 0.25mm maximum per side are not included
VER 1.4
30
ACE5372
Low Power Real-Time Clock (RTC)
Notes
ACE does not assume any responsibility for use as critical components in life support devices or systems
without the express written approval of the president and general counsel of ACE Electronics Co., LTD.
As sued herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and shoes failure to perform when properly used in
accordance with instructions for use provided in the labeling, can be reasonably expected to result in
a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can
be reasonably expected to cause the failure of the life support device or system, or to affect its safety
or effectiveness.
ACE Technology Co., LTD.
http://www.ace-ele.com/
VER 1.4
31