SH3000EK SEMTECH [Semtech Corporation], SH3000EK Datasheet - Page 7

• Manufacturer Part Number: SH3000EK
• Description: Reset Management and Clock Management Support IC for Microcontrollers
• Manufacturer: SEMTECH [Semtech Corporation]

Clock Management System
managing clocks, a versatile and accurate “any
frequency” clock synthesizer (see Figure 4).
range of 62.5 kHz to 16.0 MHz, with worst-case
resolution of 0.0256% (256 ppm). The internal
32.768 kHz clock can also be routed to the CLK
(and HF oscillator stopped for energy savings).
Management System are aimed towards the systems
that utilize a microcontroller, a microprocessor, a DSP or
an ASIC.
intentions of the host processor, an industry first. The
SH3002 shuts down its clock output when it senses that
the host processor issued a STOP instruction.
Subsequently, the SH3002 idles, consuming less than
10 µA. As soon as the host exits the STOP mode, the
SH3002 instantaneously starts to supply a stable clock
(<2 µs wake-up).
resonator or a crystal as the frequency determining
element, must wait at least several hundred
microseconds (for a resonator), or as much as 100 ms or
more (for a HF crystal), to re-start the oscillator. The
SH3002 allows the response to and service of an event
to finish with a speed previously unattainable for a
simple microprocessor. A system with a traditional clock
approach can be as much as 100x – 10,000x slower.
Copyright ©2002-2005 Semtech Corporation
32.768 kHz
SYSTEM MANAGEMENT
The SH3002 provides a flexible tool for creating and
It is capable of generating any frequency in the
The objectives, features, and behavior of the Clock
The SH3002 permits the automatic sensing of the
A typical system, constructed with a ceramic
÷
16
From / To
Serial I/O
2048 Hz
Frequency Locked Loop
Frequency
Set value
13-bit
Logic
Figure 4. Simplified HF Oscillator System
FLL On
OUT
pin
Random Noise
7
8-bit Pseudo
Generator
Clock Generator Operation
constructed from the 2:1 tunable 8.0–16.0 MHz HF
oscillator followed by a programmable “power-of-two”
post-divider (see Figure 4).
post-scale divider allow instantaneous switching
between the 32.768 kHz internal clock and divided-down
HF oscillator output. There is no settling or instability
when the switch occurs.
computing systems, when the large ratio between high
and low frequency of operations allows for
correspondingly large and instantaneous savings in
power consumption.
the frequency of the clock on the CLK
± 0.025%, and maintain it to ± 0.5% over temperature.
This compares favorable with the typical ± 0.5% initial
clock accuracy and ± 0.6% overall temperature stability
of ceramic resonators. The SH3002 replaces the typical
resonator, using less space and providing better
performance and functionality.
32.768 kHz signal. The absolute accuracy and stability
of the HF clock depends on the quality of the 32.768 kHz
internally generated clock; the low-frequency (LF)
Oscillator System is described later in this document.
8, 16, 32, 64, 128)
(Divide by 1, 2, 4,
DCO Code
The frequency synthesizer in the SH3002 is
The Clock Source selector and the programmable
This is a preferred method for clock control in
When the HF oscillator is operating alone, it can set
The HF oscillator can also be locked to the internal
Register
18-bit
Post-scaler
Spreading
Clock Source
Spectrum
Controls
SH3002 MicroBuddy™
1
0
V1.20
Clock Buffer
HF Digitally
Controlled
8-16 MHz
Oscillator
and Glue
Logic
OUT
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Clock On
pin to
S
TART
/S
CLK
CLK
16
15
DCO On
TOP
Force
OUT
IN