sh3001imltrt Semtech Corporation, sh3001imltrt Datasheet - Page 7

• Manufacturer Part Number: sh3001imltrt
• Description: Sh3001 Microbuddy Real-time Clock And Clock Management Support Ic For Microcontrollers
• Manufacturer: Semtech Corporation

Special Operating Modes
connections to the In and Out terminals of the host’s
oscillator. For example, a bank of SH3001 chips can
generate several different frequencies for simultaneous
use in the system, all controlled by a single micro (and
possibly sharing one 32.768 kHz crystal by chaining the
CLK32 pin to X
the CLK
output on the CLK
operating mode is automatically recognized by the
SH3001.
Real-Time Support
specifically designed for various real time support
functions. They are the Real-Time Clock and the
Periodic Interrupt / Wakeup Timer. Both of these units
as well as other functions of the SH3001 depend on the
internal 32.768 kHz clock for accuracy.
the SH3001 can provide a processor clock accuracy of
± 256 ppm (± 0.0256%) and the accuracy of the real-
time system of ± 4 ppm (± 0.0004%).
Copyright ©2002-2005 Semtech Corporation
SYSTEM MANAGEMENT
12.5 pF Load
Capacitance
32.768 kHz
The SH3001 can operate stand-alone, without
The SH3001 has two support modules that are
With one external component (a 32.768 kHz crystal),
Crystal
V
REG
IN
pin should be connected to V
IN
CLK
pin on the next device). In this case
OUT
X
X
V
V
IN
OUT
SEL
SS
SS
5
6
7
8
1
pin is continuous; the correct
Lock / Unlock
Logic
SS
Figure 2. Simplified LF Oscillator System
4-bit Value
. The clock
6-bit Value
I
R
NTERNAL
REF
7
O
N
A microcontroller might not have a STOP command.
With the SH3001, this controller can do a “simulated”
STOP by issuing an instruction to the SH3001 to stop
the clock. This command is accepted only if the Periodic
Interrupt / Wakeup Timer has started (otherwise, once
the system is put to sleep, it would never wake up
again). This mode of operations is only possible if the
host processor is capable of correct operations with
clock frequency down to zero, and keeps all of the
internal RAM alive while the clock is stopped.
Low Frequency (LF) Oscillator System
internal circuits and to the dedicated output pin, CLK32.
operations when V
available.
RC oscillator takes over. It supplies the 32.768 kHz
clock for start-up and initialization. Once the crystal has
started and stabilized, the internal 32.768 kHz clock
switches to the very accurate crystal frequency; see
Figure 2.
4-bit Value
Oscillator
This module provides the 32.768 kHz clock to all
If enabled, the CLK32 output continues normal
When the power is first applied to the SH3001, the
X-tal stable?
RC
Internal R
Lock Logic
REF
DD
is absent and backup power is
SH3001 MicroBuddy™
V1.15
CLK32 O
32.768 kHz
Internal
From / To
Serial I/O
Clock
www.semtech.com
N
CLK32
13