DS1670
Portable System Controller
www.dalsemi.com
FEATURES
Provides real time clock:
− Counts seconds, minutes, hours, date of
the month, month, day of the week, and
year with leap year compensation valid up
to 2100
− Power control circuitry supports system
power-on from day/time alarm
Microprocessor monitor:
− Halts microprocessor during power fail
− Automatically restarts microprocessor
after power failure
− Monitors pushbutton for external override
− Halts and resets an out of control
microprocessor
NV RAM control:
− Automatic battery backup and write
protection to external SRAM
3-channel, 8-bit analog-to-digital converter
Simple 3-wire interface
3.3V operation
PIN ASSIGNMENT
VBAT
1
20
ST
VCCO
2
19
VCC
SCLK
3
18
X1
I/O
4
17
X2
CS
5
16
AIN0
CEI
6
15
AIN1
CEOL
7
14
AIN2
CEOH
8
13
RST
INT
9
12
BLE
GND
10
11
BHE
20-Pin TSSOP (4.4mm)
20-Pin SOIC (300 mil)
Package Dimension Information can be found at:
http://www.dalsemi.com/datasheets/mechdwg.html
ORDERING INFORMATION
DS1670E
DS1670S
20-pin TSSOP
20-pin SOIC
DESCRIPTION
The Portable System Controller is a circuit, which incorporates many of the functions necessary for low
power portable products integrated into one chip. The DS1670 provides a Real Time Clock, NV RAM
controller, microprocessor monitor, and a 3-channel, 8-bit analog-to-digital converter. Communication
with the DS1670 is established through a simple 3-wire interface.
The Real Time Clock (RTC) provides seconds, minutes, hours, day, date, month, and year information
with leap year compensation. The RTC also provides an alarm interrupt. This interrupt works when the
DS1670 is powered by the system power supply or when in battery backup operation so the alarm can be
used to wake up a system that is powered down.
Automatic backup and write protection of an external SRAM is provided through the VCCO, CEOL , and
CEOH pins. The backup energy source used to power the RTC is also used to retain RAM data in the
absence of VCC through the VCCO pin. The chip-enable outputs to RAM ( CEOL and CEOH ) are
controlled during power transients to prevent data corruption.
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