EVK-SH3000USB - Semtech - Datasheet.Live

SH3002 MicroBuddy™

Reset Management and Clock Management

Support IC for Microcontrollers

SYSTEM MANAGEMENT

Description

The programmable SH3002 MicroBuddy™ (µBuddy™)

provides mandatory microcontroller support functions:

♦ CPU Supervisor

♦ Clock Management System

♦ Auxiliary functions

Three components make a complete system: any

microcontroller, the SH3002, and a bypass capacitor.

This low-cost system would consume very little power and

have clock-frequency accuracy of ± 0.5%.

The SH3002 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 SH3002. The

SH3002 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 nonvolatile 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).

Applications

♦ Home automation and security

♦ Consumer products

♦ Portable/handheld computers

♦ Industrial equipment

♦ Any microcontroller-based product

Features

♦ Highly integrated IC

- 3 mm x 3 mm x 0.9 mm 16-lead MLP (QFN) package

♦ CPU Supervisor

- Low VDD reset programmable from 2.3 V to 4.3 V

- Both active-high and active-low reset outputs

♦ Clock Management System

- Replaces high-frequency (HF) crystal or resonator

- Programmable clock output from 32.768 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

♦ Operates from 2.3 V to 5.5 V

- Ideal for battery-operated devices

♦ IDD <850 µA / 2 MHz, <3 mA / 16 MHz, <10 µA / standby

Pin Configuration

3mm MLP (QFN) Package

SH3002

µ

BTM

1

2

3

4

5 6 7 8

12

11

10

9

16 15 14 13

VSS

VREG

VDD

NC

VSS

RREF

NRST

TEST (VSS)

RST

CLK32

IO/INT

CLKIN

CLKOUT

Typical Application Circuit

SH3002

µ

BTM

1

2

3

4

5

6

7

8

12

11

10

9

16

15

14

13

µ

Controller

VDD

XIN

XOUT

GPIO WITH INT

NRESET

GND

V+

CBYPASS

Semtech, the Semtech logo, MicroBuddy, µBuddy, and µB are

marks of Semtech Corporation. All other marks belong to their

res

p

ective owners.

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Description

Ordering Information

SH3002IMLTR IC MLP 3 x 3 mm, 16 pins, temp. range -40° C to +85° C

EVK-SH3000USB SH3000 evaluation kit

SH3000EK.pdf SH3000 Evaluation Kit User Guide

SH3000UM.pdf SH3000 Reference Manual

Block Diagram

CLK32

Microcontroller

V+

VDD 32.768

KHZ XIN XOUT RESET I/O PIN

VSS

NC

VREG

LF Oscillator

Reset Drivers

& Logic

VDD Monitor

HF Oscillator

& FLL

Periodic Interrupt

/ Wake-up Timer

RC

Oscillator

Regulators

Nonvolatile Memory

Calibration &

Default Settings

Serial I/O

Control Logic

8

Clock Driver &

Start/Stop Logic

Post-scaler

2 3

4

9

10

11

12

5

6

7

13

14

1516

Interrupt

VDD

VSS

NC

Voltage

Reference

CLKOUT

CLKIN

RREF

RST

NRST

TEST

IO/INT

SH3002 µBuddy™

1

VSS

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Pin Descriptions

Pin Name Type Function

1 VSS Power Ground, 0 V. All VSS pins and TEST (VSS) pin must be connected together.

2 VREG Power

Output of internal Voltage Regulator, 2.2 V nominal. This pin can power external loads

of <5 mA. If load is “noisy” it requires a bypass capacitor. May be left unconnected or

used as a high logic level signal for CLKSEL pin (see below).

3 VDD Power Main power supply, +2.3 to +5.5 V.

4 NC Not connected - reserved

5 NC Not connected - reserved

6 NC Not connected - reserved

7 VSS Power Ground, 0 V. All VSS pins and TEST (VSS) pin must be connected together.

8 VSS Power Ground, 0 V. All VSS pins and TEST (VSS) pin must be connected together.

9 RREF Analog

Optional 1 MOhm external bias resistor for the internal 32.768 kHz RC oscillator. Can

be used to set, trim or modulate the internal RC oscillator. Keep open if not used.

10 NRST Digital Out

A

ctive low system reset output. Asserted with a strong low state when a reset condition

occurs. Weakly pulled to VDD internally when not active. This signal is valid for VDD as

low as 1 V. Keep open if not used.

11 RST Digital Out

Active high system reset output. Asserted with a strong high state when a reset

condition occurs. Weakly pulled to VSS internally when not active. This signal is valid

for VDD as low as 1 V. Keep open if not used.

12 TEST (VSS) Digital In Factory test enable. All VSS pins and TEST (VSS) pin must be connected together.

13 CLK32 Digital Out

Buffered internal 32.768 kHz clock, derived according to the CLKSEL pin setting. This pin

uses backup power for the buffer when VDD is not present. When driving high, this signal

is either at VBAK or VDD (if VDD is higher than the reset threshold). When enabled, this

signal runs continuously independent of CLKOUT activity. Minimize the external load to

reduce power consumption during backup operations. When disabled, this pin is driven

to VSS. Keep open if not used.

14 IO/INT I/O

Serial communications interface and interrupt output pin. This pin is internally weakly

pulled to the opposite of the programmed interrupt polarity. For example, if interrupt is

programmed to be active low, this pin is weakly pulled to VDD when inactive. Keep

open if not used.

15 CLKIN Digital In

Clock activity sense input. Used to detect when the target microcontroller enters stop

mode (which disables its clock). Connect to the microcontroller’s clock output or

oscillator output pin. Connect to VSS when not used. CLKIN must not be left open.

16 CLKOUT Digital Out

Programmable high frequency clock output. Connect to the target microcontroller’s clock

input or oscillator input pin. Keep open if not used.

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Functional Description

The SH3002 is a single-chip support system for

microcontrollers, microprocessors, DSPs and ASICs. It

consists of four major functional blocks, each block

having numerous enhancements over alternative

solutions.

The major modules are the CPU Supervisor, the

Clock Management System, and the Auxiliary functions.

The entire chip is controlled by the set of internal

registers and accessed via the single-pin serial interface.

All of the settings, configuration, and calibration or

operating parameters are programmable and re-

programmable at any time. All of the parameters

required for stand-alone operations are initialized on

reset from the built-in factory-programmed nonvolatile

memory. This allows the SH3002 to operate

autonomously for most of its supervisory functions. The

stand-alone operations do not require the use of the

serial interface or any of the initialization and control

operation, but without these, the full potential benefit of

the SH3002 might not be realized.

In the preferred configuration, where the SH3002 is

tightly coupled to the target micro, the SH3002 offers an

unprecedented level of design flexibility in clock and

power usage management.

The SH3002 is a particularly desirable integration

because the built-in features interact and meld to

produce more useful system level functions.

For example, on power up, the SH3002 can quickly

release the reset lines on its CPU Supervisor module

because the clock signal from the Clock Management

System is guaranteed to be running and stabilized. An

ordinary reset circuit must hold reset active for a long

time to allow an unknown crystal to start up and

stabilize.

The SH3002 offers several ways to minimize system

power consumption, such as allowing the target

processor to enter deep sleep by stopping its clock

completely, and to wake up as often as necessary with

no external support. The clock can be programmed to

start up at a given frequency, and software can adjust it

dynamically to manage power consumption and different

operating modes.

Users should consider the interactions of the major

functional blocks to gain the maximum advantage from

the SH3002.

The individual functional blocks are described in the

following sections.

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

CPU Supervisor

The SH3002 has two supervisory functions that

manage the reset of the target processor, a low VDD

monitor (Brownout Detector), see Figure 1.

Both functions are integrated with the Clock

Management System to provide a more complete

system solution than stand-alone components.

The SH3002 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 SH3002 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 Max Units

VBO for min code

(000000)

2.27 2.3 2.33 V

VBO for max code

(111111)

4.2 4.3 4.4 V

Step resolution 33 mV

The default VBO value is loaded on power-up from the

factory-programmed 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 a 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 SH3002

provides a fast-starting clock that is free of crystal start-

up time requirements. This gives the SH3002 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 SH3002 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.

Figure 1. CPU Supervisor --- Low VDD / Brownout Detector, Watchdog, Reset logic & Drivers

Noise Filter

1

VDD

VHIGH

VLOW

Threshold

D/A

4.40 V

2.30 V Hysteresis

50mV TYP.

Reset Logic

&

Minimum

Duration Timer

PWROK

Temperature-

compensated

Voltage

Reference

10

NRST

11

RST

VDD

20

K

20

K

UNDERFLOW 1→0

32.768kH

z

6-bit Value

From / To

Serial I/O

Write-once

Initialization Logic

Lock Logic

RESET

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Since the clock is only active for the last 1 or 2 ms of

the reset interval, when VDD has already been valid for

some time, energy savings are realized and the startup

of the whole system is made easier. The commonly

used reset approach forces the processor to turn the

oscillator on and to run at full speed (thus consuming full

power) during the critical time when the (possibly

depleted) battery is trying to raise VDD to an acceptable

level. In contrast, the SH3002 allows the power source

to charge the bypass capacitors and raise the level of

VDD with little additional load. Only when power has

stabilized is the target micro permitted to start expending

energy.

When a brownout event occurs, the SH3002

continues to provide the clock to the target processor,

but at a reduced frequency between 500 kHz and

1.0 MHz. After a delay of 2 ms this clock is stopped,

automatically lowering the energy consumption of the

whole system, see Figure 2.

A Noise Filter (see Figure 1) prevents reset

activations from noise and small power glitches on the

VDD line. A typical behavior is shown in Figure 3 for the

VDD level just above VBO and various amplitudes and

durations of the negative-going spikes.

When VDD is falling, both reset lines are guaranteed

to activate within 5 µs from the time VBO is crossed over.

VDD

RST

NRST

CLKOUT

Figure 2. Operations of low VDD / Brownout Detector

1V

VBO

VBO + VHYST

3-5ms

12ms minimum

2 ms2 ms 1 ms

Undefined

Normal

FOUT

Reduced FOUT

0.5-1.0 MHz

6ms

0

5

10

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Amplitude, V

Duration, µs

Guaranteed NO reset

Guaranteed reset

Duration

Amplitude

Figure 3. Response to negative voltage spikes

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Clock Management System

The SH3002 provides a flexible tool for creating and

managing clocks, a versatile and accurate “any

frequency” clock synthesizer (see Figure 4).

It is capable of generating any frequency in the

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 CLKOUT pin

(and HF oscillator stopped for energy savings).

The objectives, features, and behavior of the Clock

Management System are aimed towards the systems

that utilize a microcontroller, a microprocessor, a DSP or

an ASIC.

The SH3002 permits the automatic sensing of the

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).

A typical system, constructed with a ceramic

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.

Clock Generator Operation

The frequency synthesizer in the SH3002 is

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).

The Clock Source selector and the programmable

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.

This is a preferred method for clock control in

computing systems, when the large ratio between high

and low frequency of operations allows for

correspondingly large and instantaneous savings in

power consumption.

When the HF oscillator is operating alone, it can set

the frequency of the clock on the CLKOUT pin to

± 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.

The HF oscillator can also be locked to the internal

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.

Post-scaler

(Divide by 1, 2, 4,

8, 16, 32, 64, 128)

Figure 4. Simplified HF Oscillator System

32.768 kHz

START/STOP

16

15

CLKOUT

CLKIN

Clock Buffer

and Glue

Logic

HF Digitally

Controlled

Oscillator

8-16 MHz

18-bit

DCO Code

Register

Clock On

Force

DCO On

Clock Source

1

0

Spectrum

Spreading

Controls

Frequency Locked Loop

Logic

13-bit

Frequency

Set value

÷ 16 2048 Hz

8-bit Pseudo

Random Noise

Generator

FLL On

From / To

Serial I/O

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

The SH3002 employs a Frequency Locked Loop

(FLL) to synchronize the HF clock to the 32.768 kHz

reference. This architecture has several advantages

over the common PLL (Phase Locked Loop) systems,

including the ability to stop and re-start without

frequency transients or instability, and with instant

settling to a correct frequency. The conventional PLL

approach invariably includes a Low-Pass Filter that

requires a long settling time on re-start.

The primary purpose of the FLL is the maintenance

of the correct frequency while the ambient temperature

is changing. As the temperature drift of the HF oscillator

is quite small, any corrective action from the FLL system

is also small and gradual, commensurate with the

temperature variation.

The FLL system in the SH3002 is unconditionally

stable.

To set a new frequency for the FLL, the host

processor writes the 13-bit Frequency Set value. The

resulting output frequency is calculated using simple

formulas [1] and [2] (reference frequency is 32.768 kHz):

FOSC = 2048 Hz * (Frequency Set value + 1) [1]

FOUT = FOSC / (Post-divider setting) [2]

For example, a post-divider setting of ÷8 and the

Frequency Set value of 4000 (0x0FA0) produce an

output frequency of 1.024 MHz.

Programmable Spectrum Spreading

Most commercial electronic systems must pass

regulatory tests in order to determine the degree of their

Electromagnetic Interference (EMI) affecting other

electronic devices. In some cases compliance with the

EMI standards is costly and complicated.

The SH3002 offers a technique for reducing the

EMI. It can be a part of the initial design strategy, or it

can be applied in the prototype stage to fix problems

identified during compliance testing. This feature of the

SH3002 can greatly reduce the requirements for

radiofrequency shielding, and permits the use of simple

plastic casings in place of expensive RFI-coated or

metal casings.

The SH3002 employs Programmable Spectrum

Spreading in order to reduce the RF emissions from the

processor’s clock. There are five (5) possible settings;

please see Table 2 for operating and performance

figures in the 8-16 MHz range.

Spectrum Spreading is created by varying the

frequency of the HF oscillator with a pseudo-random

sequence (with a zero-average DC component). The

Maximum-Length Sequence (MLS) 8-bit random number

generator, clocked by 32.768 kHz, is used. Only 4, 5, 6,

or 7 bits of the generated 8-bit random number are used,

according to the configuration setting.

Maximum fluctuations of the frequency depend on

the selected frequency range and the position within the

range. Selecting the HF oscillator frequency to be near

the high end of the range limits the peak variations to

± 0.1%, ± 0.2%, ± 0.4%, or ± 0.8% (corresponding to the

configuration setting).

Special Operating Modes

The SH3002 can operate stand-alone, without

connections to the In and Out terminals of the host’s

oscillator. For example, a bank of SH3002 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 XIN pin on the next device). In this case

the CLKIN pin should be connected to VSS. The clock

output on the CLKOUT pin is continuous; the correct

operating mode is automatically recognized by the

SH3002.

A microcontroller might not have a STOP command.

With the SH3002, this controller can do a “simulated”

STOP by issuing an instruction to the SH3002 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.

Table 2. EMI reduction with Spectrum Spreading

Setting

En CFG1 CFG0

Spreading

Bandwidth

kHz

Peak EMI

Reduction

(guaranteed)

db

Peak EMI

Reduction

(measured)

db

0 X X Off 0 0

1 0 0 32 -3 -3

1 0 1 64 -6 -7

1 1 0 128 -9 -10

1 1 1 256 -12 -15

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Low Frequency (LF) Oscillator System

This module provides the 32 kHz clock to all internal

circuits and to the dedicated output pin, CLK32.

If enabled, the CLK32 output continues normal

operations when VDD is absent and backup power is

available.

Just like the VBO value for the Reset circuit, the

default calibration values for the RC oscillator are loaded

on power-up from the factory-programmed nonvolatile

memory. They can be re-programmed at any time or

they can be permanently protected from any changes by

setting the Lock flag or a write-protect flag. Factory

calibration brings the frequency of the RC oscillator

within ±3 % of the 32768 Hz for the internal reference

resistor, and ± 2% for the external 1 MΩ 1% resistor,

over the entire temperature and supply voltage range.

The frequency of the RC oscillator can be tuned or

modulated by varying the external reference resistor,

which should be located as close as possible to RREF,

pin 9.

9 RC

Oscillator

13

Internal

32.768 kHz

Clock

External

Reference

Resistor

1 MΩ 1% or

variable

Internal RREF

Figure 5. Simplified LF Oscillator System

1

CLK32

RREF

8

VSS

CLK32 ON

4-bit Value 6-bit Value 4-bit Value

Lock / Unlock

Logic Lock Logic

INTERNAL

RREF ON

From / To

Serial I/O

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Periodic Interrupt / Wakeup Timer

Simple and versatile, the Periodic Interrupt / Wakeup

Timer can be used to create very accurate recurring

interrupts for use by the host micro. With some minimal

software support from the host processor, it can also be

used to create alarms, with practically unlimited duration.

While the timer is running, the host processor can be

halted, consuming no energy. The interrupt wakes up

the processor, which can perform the requisite task and

go back to sleep, until the next periodic interrupt.

This mode of operation can achieve extremely low

average power consumption.

A 32-bit counter clocked by 32.768 kHz, producing a

minimum interval of 30.5 µs and the maximum interval of

36.4 hours, creates the Timer.

After reset, the Timer is stopped until the new value

for the time interval is written into the 4-byte Time

Interval register. When the least significant byte (LSB) is

written, the whole value is moved to the Time Interval

latch, the counter is reset and starts to increment with

the 32.768 kHz clock.

When the 32-bit comparator detects a match, an

interrupt is generated and the counter is reset and starts

the next timing cycle.

Although the counter cannot be written to, the

current value from the counter can be read at any time.

The whole 32-bit value is loaded into the 32-bit Current

Timer Value latch when the least significant byte is read.

This prevents errors stemming from the finite time

between the readings of individual bytes of the current

value.

Auxiliary functions

Voltage Regulator

Pin VREG can be used as a nominal 2.20 V reference

voltage or a supply source for small loads (<2 mA). A

bypass capacitor might be necessary between this pin

and VSS if the load generates large current transients or

a low ripple reference is required.

14

Figure 6. Periodic Interrupt / Wakeup timer

IO/INT

32-bit Time Interval

32-bit Counter

32-bit Comparator

32-bit Latch

Interrupt

Logic

Serial I/O

RESET

LSB MSB

32-bit Latch

LOAD

Current Timer

Value

LSB MSB

32.768 kHz

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Interrupt and Serial Interface

A single line is used to convey bi-directional

information between the SH3002 and the processor, and

as the interrupt line to the processor.

The polarity of the interrupt signal is programmable.

The SH3002 and the host microcontroller

communicate using a single wire, bi-directional

asynchronous serial interface. The bit rate is

automatically determined by the SH3002. . At the

fastest possible rate, a read or write access of a single

byte from the register bank takes 5 µs.

The SH3002 contains 36 addressable registers

located at 0x00–0x1F. Some of these registers are

accessed through a page operation. Pin 14, IO/Int, is

the serial communications interface and interrupt output

pin. This pin is internally weakly pulled to the opposite of

the programmed interrupt polarity. For example, if

interrupt is programmed to be active low, this pin is

weakly pulled to VDD when inactive.

As shown in Figure 7, the SH3002 and the host

communicate with serial data streams. The host always

initiates communication. A data stream consists of the

following (in this order):

• 3-bit start field

• 3-bit read/write code

• 5-bit address field

• 1 guard bit

• 8-bit data field

• 2 parity bits

Plus, for write streams only:

• 1 guard bit

• 2 acknowledge (ACK) bits

The 3-bit start field (1,0,1 or 0,1,0, depending on

interrupt polarity) uses the middle bit to determine the bit

period of the serial data stream.

The 3-bit read/write code consists of 1,1,0 for a

read, or 0,1,1 for a write. This protects against early

glitches that might otherwise put the interface into an

invalid read or write access mode.

The 5-bit address field contains the address of the

register.

A single guard bit gives the interface a safe period in

which to change data direction. The value of a guard bit

does not matter.

The 8-bit data field is written to (read from) the

register.

Two parity bits: The first parity bit is high when there

are an odd number of bits in the read/write, address and

data fields; the second parity bit is the inverse of the first.

For write streams only, a guard bit is appended to

the stream (to allow safe turnaround), and then two

acknowledge bits, which are a direct copy of the parity

bits, are driven back to the host to indicate a successful

write access.

Two guard bits are appended to the end of the

access stream (read or write). The host can not start the

next access before receiving these bits.

The interface is self-timed based on the duration of

the start bit field, and communication can take place

whenever CLKOUT is active, either at 32.768 kHz or at a

higher frequency. If the host microcontroller is running

synchronously to the CLKOUT generated by the SH3002

(which should generally be the case), then a minimum of

4 CLKOUT cycles per bit are required to maintain

communication integrity. If the host’s serial interface is

asynchronous to CLKOUT, then a minimum of 52 cycles

per bit are necessary. A maximum of 1024 CLKOUT

cycles per bit field is supported.

Table 3 displays the minimum and maximum bit

periods for the serial communications for CLKOUT

frequencies of 16 MHz, 8 MHz, and 2 MHz.

Table 3: Minimum/Maximum Serial Bit Timing

CLKOUT

Frequency

Minimum Bit

Period

(host

synchronous

to CLKOUT)

Minimum Bit

Period

(host

asynchronous

to CLKOUT)

Maximum Bit

Period

16 MHz 250 ns 3.25 µs 63.9 µs

8 MHz 500 ns 6.5 µs 127 µs

2 MHz 2 µs 26 µs 511 µs

Interrupt Interface

The serial communications line to the SH3002 (Pin

14, IO/Int) also serves as the interrupt to the host

microcontroller. The polarity of the interrupt is software

programmable using the interrupt polarity bit (bit 6) of the

IPol_RCtune register (R0x11). This pin is asserted for

four cycles of CLKOUT, and then returns to the inactive

state.

The interrupt line is used by the Periodic

Interrupt/Wake-up Timer to interrupt the host when it

reaches its end of count.

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

IO/INT timing scenarios

1. INT disabled, uP initiates write access. Active high interrupt.

uBuddyIOOut

uPIOOut A0 A4 XXX D0 D7

...

CombinedIO A0 A4 XXX D0 D7

... ...

2. INT active (high), uP initiates write access

uBuddyIOOut

uPIOOut

CombinedIO

XXX

State Idle Pre-

start Start Post-

Start A0 A4 Guard0 D0 D7... ... Guard1 Idle

XXX

State

If the interrupt did not get cleared,

then it will activate again here

4. INT disabled, uP initiates read access

uBuddyIOOut

uPIOOut A0 A4 XXX

...

CombinedIO A0 A4 XXX D0 D7

... ...

State Idle Pre-

start Start Post-

Start A0 A4 Guard0 D0 D7

... ... Guard2 Idle

D0 D7...

P0 P1

ACK0 ACK1

RW0 RW1 RW2

A0 A4 XXX D0 D7

...

A0 A4 XXX D0 D7... ...

XXX

Pre-

start Start Post-

Start A0 A4 Guard0 D0 D7

... ... Guard1

XXX

P0 P1

ACK0 ACK1

RW0 RW1 RW2

ACK0 ACK1

Guard2 Guard3

Pendin

g-start

IN

T

Idle Pendin

g-start

IN

T

3. INT active (low), uP initiates write access

uBuddyIOOut

uPIOOut

CombinedIO

State

If the interrupt did not get cleared,

then it will activate again here

A0 A4 XXX D0 D7

...

A0 A4 XXX D0 D7

... ...

XXX

Pre-

start Start Post-

Start A0 A4 Guard0 D0 D7... ... Guard1

XXX

P0 P1

ACK0 ACK1

RW0 RW1 RW2 Guard2 Guard3

Pendin

g-start

IN

T

Idle Pendin

g-start

IN

T

ACK0 ACK1

RW0 RW1 RW2 Guard3

Figure 7: Serial Communication Timing Diagram

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Note: The SH3002 is ESD-sensitive.

Description Symbol Min Max Units

Supply voltages on VDD relative to ground VDD -0.5 5.5 V

Input voltage on CLKIN, IO/INT, TEST VIN1 -0.5 VDD + 0.5 V

Input voltage on CLKSEL VIN2 -0.5 VREG + 0.5 V

Input current on any pin except VREG IIN1 10 mA

Input current on VREG IIN2 150 mA

Ambient operating temperature TOP -40 85 ºC

Storage temperature TSTG -55 160 ºC

Operating Characteristics

Parameter Symbol Min Typ Max Units Notes

Case temperature TOP –40 +85 °C

Supply voltage VDD 2.3 5.5 V

Supply current, CLKOUT = 16 MHz* IDD 3 mA

Supply current, CLKOUT = 8 MHz* IDD 1.8 mA

Supply current, CLKOUT = 2 MHz* IDD 0.9 mA

Standby current, 32.768 kHz RC oscillator** ISB 10 µA CLK32

disabled

*Note: Assuming load on CLKOUT < 20 pf

**Note: Assuming temperature < 60ºC

Electrical Specifications

Absolute Maximum Ratings

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Operating characteristics of 32.768 kHz RC oscillator

Parameter Symbol Min Typ Max Units

External 1 MOhm referenced nominal frequency Fext 32.768 kHz

Internal 1 MOhm referenced nominal frequency Fint 32.768 kHz

CLK32 duty cycle DC 40 60 %

Programmed frequency accuracy at 25°C Fst -1.5 +1.5 %

Absolute accuracy over temperature and supply

(external 1 MOhm)

Fde ±2 %

Absolute accuracy over temperature and supply

(internal 1 MOhm)

Fdi ±3 %

Frequency temperature stability (ext. 1 MOhm) Fse 100 ppm/°C

Frequency temperature stability (int. 1 MOhm) Fsi 200 ppm/°C

Power on startup time Tst 70 µs

CLK32 cycle to cycle jitter J 0.1 %

Operating characteristics of programmable reset

Parameter Symbol Min Typ Max Units

VDD switching threshold for Min code

(Start-up default = 2.3 V)

Vbo(min) 2.27 2.3 2.33 V

VDD switching threshold for Max code Vbo(max) 4.2 4.3 4.4 V

VDD threshold resolution Vres 33 mV

VDD hysteresis Vhys 50 mV

Falling VDD threshold switch delay Td 2.5 µs

Threshold digital-analog converter (DAC) settling time Tdac 4 ms

Minimum VDD for valid nRST VDDmin 1 V

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Operating characteristics of the high-frequency oscillator (HFO)

Parameter Symbol Min Typ Max Units

Minimum operating frequency (Start-up default = 2 MHz) Fmin 5.6 8 MHz

Maximum operating frequency Fmax 16.8 21 MHz

Frequency resolution Fres 2 kHz

Programmed frequency accuracy at 25°C Fst -0.3 +0.3 %

Frequency drift over temperature and supply Fdrift ±0.5 %

CLKOUT cycle to cycle jitter (spread spectrum off) J 0.1 %

Startup time from standby Tstart 2 µs

Settling time to 0.1% after HF digitally-controlled oscillator

(DCO) code change

Tsett 10 µs

CLKOUT duty cycle DC 40 60 %

Frequency temperature stability Fts 100 ppm/°C

Short term frequency stability Fs 0.5 %/sec

Minimum spread spectrum range SSmin 32 kHz

Maximum spread spectrum range SSmax 256 kHz

CLKOUT rise/fall time (20 pF load) Trf 3 ns

CLKOUT logic output low (4 mA load) Vol 0.25 0.4 V

CLKOUT logic output high (4 mA load) Voh -0.4 -0.25 Ref VDD

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Free Running HF DCO Frequency Deviation over Temperature for All Frequencies

-16000

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

2000

4000

-60 -40 -20 0 20 40 60 80 100 120 140

Temp. ºC

ppm Deviation

Internal 32.768 kHz Oscillator Frequency over Temperature

31800

32000

32200

32400

32600

32800

33000

33200

33400

-60 -40 -20 0 20 40 60 80 100 120 140

Temperature (ºC)

Frequency (Hz)

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Standby Current over Temperature (V

DD

= 5 V)

0.0

5.0

10.0

15.0

20.0

25.0

-60 -40 -20 0 20 40 60 80 100 120 140

Temperature (ºC)

VDD Current (µA)

Internal 32.768 kHz

Standby current over V

DD

(Temp. = 25ºC)

4

5

6

7

8

9

10

2.5 3 3.5 4 4.5 5 5.5

V

DD

(V)

VDD Current (µA)

Internal 32.768 kHz

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

V

DD

Current vs CLKOUT Frequency (V

DD

= 5.5 V, Temp. = 25ºC)

0

500

1000

1500

2000

2500

3000

3500

024681012141618

Frequency (MHz)

VDD Current (µA)

Operating V

DD

Current over V

DD

(CLKOUT = 16 MHz, Temp = 25ºC)

2000

2200

2400

2600

2800

3000

3200

2.5 3 3.5 4 4.5 5 5.5

V

DD

(V)

V

DD

Current (µA)

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Free Running HF DCO Short Term Frequency Stability (CLKOUT = 8 MHz)

-400

-300

-200

-100

0

100

200

300

-500 500 1500 2500 3500 4500 5500 6500

Time (seconds)

ppm Deviation

FLL Locked HF DCO Jitter over Jitter Bandwidth (CLKOUT = 12.8 MHz)

10

100

1000

10000

100000

0.1 1 10 100 1000 10000 100000

Jitter Bandwidth (kHz)

rms Jitter (ps)

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

Package Outline Drawing MLP 3 x 3 mm 16 pins

SH3002 MicroBuddy™

SYSTEM MANAGEMENT

For sales information and product literature,

contact:

Semtech Corporation

Human Interface Device (HID)

and System Management Division

200 Flynn Road

Camarillo, CA 93012-8790

sales@semtech.com

http://www.semtech.com/

(805)498-2111 Telephone

(805)498-3804 Fax

reserved. Semtech, the Semtech logo, MicroBuddy, µBuddy,

and µB are marks of Semtech Corporation. All other marks

belong to their respective owners.

LIMITED LICENSE GRANTED: NO WARRANTIES MADE

This specification is provided "as is" with no warranties

whatsoever including any warranty of merchantability, fitness

for any particular purpose, or any warranty otherwise arising

out of any proposal, specification or sample. Any suggestions

or comments by Semtech concerning use of this product are

opinion only, and Semtech makes no warranty as to results to

be obtained in any specific application. A license is hereby

granted to reproduce and distribute this specification for

internal use only. No other license, expressed or implied to

any other intellectual property rights is granted or intended

hereby. Authors of this specification disclaim any liability,

including liability for infringement of proprietary rights, relating

to the implementation of information in this specification.

Authors of this specification also do not warrant or represent

that such implementation(s) will not infringe such rights.