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PDF SH3000 Data sheet ( Hoja de datos )
| Número de pieza | SH3000 | |
| Descripción | Low-Power Programmable Multifunction Support IC for Microcontrollers | |
| Fabricantes | Semtech | |
| Logotipo |  |
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SYSTEM MANAGEMENT
Description
The programmable SH3000 MicroBuddy™ (µBuddy™)
provides all mandatory microcontroller support functions:
♦ CPU Supervisor
♦ Clock Management System
♦ Real Time Support
♦ Auxiliary functions
Three components make a complete system: any
microcontroller, the SH3000, and a bypass capacitor.
This low-cost system would consume very little power and
have clock-frequency accuracy of ±0.5%. A fourth
component, a 32.768 kHz watch crystal, raises the clock
frequency accuracy to ± 0.0256% (± 256 ppm).
The SH3000 can operate completely stand-alone, or
under control of the microcontroller. A single-wire
interface handles both bi-directional communications and
the interrupt / wake-up signal from the SH3000. The
SH3000 stores all configuration, calibration, parameters,
and status information in a 36-byte bank of control
registers. On reset, most of these are reloaded with
defaults from the factory-set One-Time-Programmable
(OTP) memory. The microcontroller can change any
settings on the fly. If some of the settings must remain
fixed, a comprehensive set of write-protect bits is provided
for several related groups of registers (with both
permanent write-inhibit and lock/unlock capabilities).
A backup power source may also be connected to the
SH3000. The IC can directly accommodate 2/3-cell zinc-
carbon/alkaline, 2/3-cell mercury, 2/3/4-cell NiCd/NiMH, 1-
cell Li/Li+ batteries, or a super cap.
Applications
♦ Home automation and security
♦ Consumer products
♦ Portable/handheld computers
♦ Industrial equipment
♦ Any microcontroller-based product
V+
CBYPASS
VDD
XIN
XOUT
GPIO WITH INT
SH3000 MicroBuddy™
Low-Power Programmawbwlwe.DMatauShlteieftu4Un.ccomtion
Support IC for Microcontrollers
Features
♦ Highly integrated IC
- 3mm x 3mm x 0.9 mm 16-lead MLP (QFN) package
♦ CPU Supervisor
- Low VDD reset programmable from 2.3 V to 4.3 V
- Watchdog timer with programmable timeout periods
- Both active-high and active-low reset outputs
♦ Clock Management System
- Replaces High-Frequency (HF) crystal or resonator
- Programmable clock output from 32 kHz to 16 MHz
- Speed shift between multiple clock frequencies
- Adjustable spectrum spreading for EMI reduction
- Directly supports microcontroller STOP function
- Deep sleep with instantaneous auto-wakeup
♦ Real Time Support
- 179-year real time clock, battery backup capable
- Dedicated 32 kHz buffered clock output
- Built-in trim for 32.768 kHz oscillator to ± 4ppm
- Programmable periodic interrupt / wakeup timer
♦ Auxiliary functions
- 4-byte (32-bit) scratchpad RAM, loaded on reset with
factory-set value (zero or optional ID code)
- All settings programmable in real-time, defaults
restored from OTP memory on reset
♦ Operates from 2.3 V to 5.5 V
♦ IDD <850µA / 2MHz, <3mA / 16MHz, <10µA/standby
♦ IBUP <2µA / IBSB <50nA (battery backup / standby)
♦ Protected by issued and pending
US and International Patents
Pin Configuration
16 15 14 13
VSS 1
VREG 2
VDD 3
VBAK 4
µBTM
SH3000
5678
12 TEST (VSS)
11 RST
10 NRST
9 RREF
1
2
µBTM
12
11
3 10
4 SH3000 9
NRESET
µController
GND
Typical Application Circuit with High Clock Accuracy
3mm MLP (QFN) Package
Covered by US Patent No. 6,903,986
Semtech, the Semtech logo, MicroBuddy, µBuddy, and µB are marks of
Semtech Corporation. All other marks belong to their respective owners.
2005-08-08 Copyright ©2003-2005 Semtech Corporation 1
V1.15 www.semtech.com
1 page  
SYSTEM MANAGEMENT
CPU Supervisor
The SH3000 has two supervisory functions that
manage the reset of the target processor, a low VDD
monitor (Brownout Detector) and a Watchdog Timer, see
Figure 1.
Both functions are integrated with the Clock
Management System to provide a more complete
system solution than the stand-alone components.
The SH3000 has both active high and active low reset
output pins. Both are driven strong to the active state
and weak to the inactive state. This eliminates the need
for external pull-ups and allows various reset sources to
be connected together in a wire-OR configuration. (This
makes it simple to set up a manual reset circuit.)
A set of flags in the register map indicates the
source of the reset to the system software.
Low VDD Reset
The SH3000 drives the reset pins active whenever
VDD is below the value of VBO, the brownout reset
threshold, programmable from 2.3 V to 4.3 V in average
steps of 33 mV, see Table 1.
Table 1. Programmable VBO Values
Parameter
Min Typ
VBO for min code
(000000)
2.27 2.3
VBO for max code
(111111)
4.2 4.3
Step resolution
25 33
Max
2.33
Units
V
4.4 V
41 mV
SH3000 MicroBuddy™
www.DataSheet4U.com
The default VBO value is loaded on power-up from
the factory-programmed OTP nonvolatile memory. It
can be re-programmed at any time or it can be
permanently protected from any changes by setting the
VBO Lock flag or an OTP write-protect flag.
On power up both the active-high and active-low
reset signals are driven active. These outputs are
typically valid for a VDD level of at least 0.5 V, and
guaranteed to be valid for a VDD level of 1.0 V.
The reset outputs remain active until VDD rises and
stays above the level of (VBO + VHYST), where VHYST is
a small fixed amount of hysteresis, nominally 50 mV,
added to prevent nuisance reset activations (when VDD
slowly changes near the level of VBO and some noise or
power glitching is present).
At the level of (VBO + VHYST) the power supply is
considered valid. In case of the initial power-up, the
reset is then driven inactive once 6 ms of valid power
have elapsed. In the case of brownout, the reset is
released after a delay of 6 ms (but no less than 12 ms
from the beginning of the brownout).
Such a fast reset is possible because the SH3000
provides a fast-starting clock that is free of crystal start-
up time requirements. This gives the SH3000 an
advantage over most external reset circuits, which must
have a long reset pulse duration to accommodate long
and unpredictable crystal start-up times.
The SH3000 guarantees that a valid and stable
clock is available 2 ms before the reset signals are
negated, so that internal synchronous reset and
initialization of the target micro can proceed normally.
VDD Noise Filter
1
Temperature- 4.40 V VHIGH
compensated
Threshold
Voltage
Reference
2.30 V VLOW
D/A
Lock Logic
6-bit Value
RESET
CLKOUT
Hysteresis
50mV TYP.
32kHz
Write-once
Initialization Logic
32kHz
PWROK
Reset Logic
&
Minimum
Duration Timer
UNDERFLOW 1→0
RESET
VDD
20K 20K
RST
11
NRST
10
7-bit Down Counter
÷ 256
÷ 128
Mode
Load
7-bit Watchdog
Timeout Value
Watchdog
Reload Control
Alternating Codes
Logic
0x5A / 0xC3
Figure 1. CPU Supervisor --- Low VDD / Brownout Detector, Watchdog, Reset logic & Drivers
From / To
Serial I/O
Copyright ©2003-2005 Semtech Corporation
5
V1.15 www.semtech.com
5 Page 
SYSTEM MANAGEMENT
The crystal oscillator has the useful feature of
adjustable load capacitors. It permits tuning of the circuit
for initial tolerance of the crystal (often ±20 ppm) as well
as an adjustment for the required load capacitance (with
possible variations from the PCB layout). While the
oscillator was designed for a crystal with a nominal load
capacitance of 12.5 pF, the circuit accommodates any
value from ~7 pF to 22 pF (depending on parasitics of
the layout). All of these corrections can be performed
when the part is already installed on the PCB, in the
actual circuit.
The default value for load capacitance (12.5 pF)
loaded on power-up from the factory-programmed OTP
nonvolatile memory can be re-programmed at any time
(following a secure process of unlocking the load
capacitance value register and immediately writing a
new setting), or it can be completely protected from any
changes by a permanent OTP write-protect flag.
This adjustment can set the frequency of the crystal
oscillator to within ±4ppm of the ideal value. As a
reference, a typical 32.768 kHz crystal changes its
frequency 4ppm for a 10°C change in temperature.
Since the temperature characteristics of crystals are well
known and stable, the host processor is free to
implement an algorithm for temperature compensation of
the crystal oscillator using the adjustable load
capacitors, with resulting accuracy of ±4ppm over the
entire temperature range.
SH3000 MicroBuddy™
www.DataSheet4U.com
Real Time Clock
Using the ±4ppm, 32.768 kHz clock from the LF
oscillator, the Real Time Clock module keeps time with
a maximum error as low as 2 minutes per year. This
compares favorably with a conventional error of 2
minutes per month for the typical RTC chip.
The hardware of the Real Time Clock is capable of
179-years of calendar operations (see Figure 6).
All counting-chain values are loaded at the same
time into corresponding registers when the Fractions
register is read. All values from registers are loaded into
the counting-chain when the Fractions register is written.
The RTC continues normal operations when VDD is
absent, if backup power is available.
LSB
LOAD 32-bit Latch
MSB
Current Timer
Value
32768 Hz
÷ 128 256 Hz
32-bit Counter
RESET
÷ ÷ ÷ ÷256 1 Hz
60
60
24 16-bit Counter
Fractions
(BIN)
LSB 0 - 255
Seconds
(BCD)
0 - 59
Minutes
(BCD)
0 - 59
Hours
(BCD)
0 - 23
Days (BIN)
0 - 65535
32-bit Comparator
LOAD 32-bit Latch
LSB 32-bit Time Interval
MSB
Interrupt
Logic
Serial I/O
IO/INT
14
Figure 6. Real Time Clock and Periodic Interrupt / Wakeup timer
Copyright ©2003-2005 Semtech Corporation
11
V1.15 www.semtech.com
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet SH3000.PDF ] | |
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