Maxim DS1086LU 3.3v spread-spectrum econoscillator Datasheet

Rev 1; 9/07
3.3V Spread-Spectrum EconOscillator
The DS1086L EconOscillator™ is a 3.3V programmable
clock generator that produces a spread-spectrum
(dithered) square-wave output of frequencies from
130kHz to 66.6MHz. The selectable dithered output
reduces radiated-emission peaks by dithering the frequency 0.5%,1%, 2%, 4%, or 8% below the programmed frequency. The DS1086L has a power-down
mode and an output-enable control for power-sensitive
applications. All the device settings are stored in nonvolatile (NV) EEPROM memory allowing it to operate in
stand-alone applications.
Applications
Features
♦ User-Programmable Square-Wave Generator
♦ Frequencies Programmable from 130kHz to
66.6MHz
♦ 0.5%, 1%, 2%, 4%, or 8% Selectable Dithered
Output
♦ Adjustable Dither Rate
♦ Glitchless Output-Enable Control
♦ 2-Wire Serial Interface
♦ Nonvolatile Settings
Printers
♦ 2.7V to 3.6V Supply
Copiers
♦ No External Timing Components Required
PCs
♦ Power-Down Mode
Computer Peripherals
♦ 5kHz Master Frequency Step Size
Cell Phones
♦ EMI Reduction
Cable Modems
♦ Industrial Temperature Range: -40°C to +85°C
Ordering Information
PART
DS1086LU
TEMP RANGE
PIN-PACKAGE
-40°C to +85°C
8 μSOP (118 mil)
Pin Configuration
Typical Operating Circuit
μP
XTL1/OSC1
XTL2/OSC2
VCC
DITHERED 130kHz TO
66.6MHz OUTPUT
VCC
N.C.
OUT
SCL*
SPRD
SDA*
VCC
GND
DS1086L
PDN
OE
DECOUPLING CAPACITORS
(0.1μF and 0.01μF)
*SDA AND SCL CAN BE CONNECTED DIRECTLY HIGH IF THE DS1086L NEVER NEEDS
TO BE PROGRAMMED IN-CIRCUIT, INCLUDING DURING PRODUCTION TESTING.
TOP VIEW
OUT 1
SPRD
2
VCC
3
DS1086L
GND 4
8
SCL
7
SDA
6
PDN
5
OE
μSOP
EconOscillator is a trademark of Dallas Semiconductor.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
DS1086L
General Description
DS1086L
3.3V Spread-Spectrum EconOscillator
ABSOLUTE MAXIMUM RATINGS
Voltage Range on VCC Relative to Ground ..........-0.5V to +6.0V
Voltage Range on SPRD, PDN, OE, SDA, and SCL
Relative to Ground* ..................................-0.5 to (VCC + 0.5V)
Operating Temperature Range ...........................-40°C to +85°C
Programming Temperature Range .........................0°C to +70°C
Storage Temperature Range .............................-55°C to +125°C
Soldering Temperature ..................See IPC/JEDEC J-STD-020A
*This voltage must not exceed 6.0V.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
Supply Voltage
High-Level Input Voltage
(SDA, SCL, SPRD, PDN, OE)
Low-Level Input Voltage
(SDA, SCL SPRD, PDN, OE)
SYMBOL
VCC
CONDITIONS
(Note 1)
MIN
TYP
2.7
3.3
MAX
UNITS
3.6
V
VIH
0.7 x
VCC
VCC +
0.3
V
VIL
-0.3
0.3 x
VCC
V
MAX
UNITS
V
DC ELECTRICAL CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
High-Level Output Voltage (OUT)
VOH
IOH = -4mA, VCC = min
Low-Level Output Voltage (OUT)
VOL
IOL = 4mA
0
0.4
VOL1
3mA sink current
0
0.4
VOL2
6mA sink current
0
0.6
Low-Level Output Voltage (SDA)
CONDITIONS
MIN
TYP
2.4
V
High-Level Input Current
IIH
VCC = 3.6V
Low-Level Input Current
IIL
VIL = 0
ICC
CL = 15pF (output at default frequency)
10
mA
Power-down mode
10
µA
Supply Current (Active)
Standby Current (Power-Down)
2
ICCQ
1
V
-1
_______________________________________________________________________________________
µA
µA
3.3V Spread-Spectrum EconOscillator
DS1086L
MASTER OSCILLATOR CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
Master Oscillator Frequency
Default Master Oscillator Frequency
SYMBOL
fOSC
f0
CONDITIONS
(Note 2)
MIN
TYP
33.3
Factory-programmed default
MAX
66.6
48.65
Δf0
f0
VCC = 3.3V,
TA = +25°C
(Notes 3,17)
Default frequency (f0)
-0.5
+0.5
DAC step size
-0.5
+0.5
Voltage Frequency Variation
ΔfV
f0
Over voltage range,
TA = +25°C (Note 4)
Default frequency
-0.75
+0.75
DAC step size
-0.75
+0.75
ΔfT
f0
Over temperature
range, VCC = 3.3V
(Note 5)
Default frequency
-2.0
+0.75
Temperature Frequency Variation
66.6MHz
-2.0
+0.75
33.3MHz
-2.5
Dither Frequency Range (Note 6)
Integral Nonlinearity of Frequency
INL
MHz
MHz
Master Oscillator Frequency
Tolerance
Δf
f0
UNITS
%
0.5
Prescaler bits JS2, JS1, JS0 = 001
1
Prescaler bits JS2, JS1, JS0 = 010
2
Prescaler bits JS2, JS1, JS0 = 100
4
Prescaler bits JS2, JS1, JS0 = 111
8
DAC Step Size
Δ between two consecutive DAC values
(Note 8)
DAC Span
%
+0.75
Prescaler bits JS2, JS1, JS0 = 000
Entire range (Note 7)
%
-0.6
%
+0.3
%
5
kHz
Frequency range for one offset setting
(Table 2)
5.12
MHz
DAC Default
Factory default register setting
500
decimal
Offset Step Size
Δ between two consecutive offset values
(Table 2)
2.56
MHz
Offset Default
OS
Factory default OFFSET register setting
(5 LSBs) (Table 2)
Prescaler bits JS4, JS3 = 00
Dither Rate
RANGE
(5 LSBs of
RANGE register)
hex
f0/8192
Prescaler bits JS4, JS3 = 01
f0/4096
Prescaler bits JS4, JS3 = 10
f0/2048
Hz
_______________________________________________________________________________________
3
DS1086L
3.3V Spread-Spectrum EconOscillator
AC ELECTRICAL CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
1
period
0.1
1
ms
0.1
0.5
ms
200
µs
100
µs
50
pF
Frequency Stable After Prescaler
Change
Frequency Stable After DAC or
Offset Change
Power-Up Time
tDACstab
tpor + tstab (Note 10)
Enable of OUT After Exiting
Power-Down Mode
tstab
OUT High-Z After Entering
Power-Down Mode
tpdn
Load Capacitance
(Note 9)
CL
Output Duty Cycle (OUT)
(Note 18)
(Note 11)
15
Default frequency
45
Rise and Fall Time (OE, PDN)
55
%
1
µs
MAX
UNITS
400
100
kHz
AC ELECTRICAL CHARACTERISTICS—2-WIRE INTERFACE
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
SCL Clock Frequency
fSCL
Bus Free Time Between a STOP
and START Condition
tBUF
Hold Time (Repeated) START
Condition
tHD:STA
LOW Period of SCL
tLOW
HIGH Period of SCL
tHIGH
Setup Time for a Repeated
START
tSU:STA
Data Hold Time
tHD:DAT
Data Setup Time
tSU:DAT
Rise Time of Both SDA and SCL
Signals
tR
Fall Time of Both SDA and SCL
Signals
tF
4
CONDITIONS
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
MIN
TYP
(Note 12)
(Note 12)
(Notes 12, 13)
(Note 12)
(Note 12)
(Note 12)
(Notes 12, 14, 15)
(Note 12)
(Note 16)
(Note 16)
1.3
µs
4.7
0.6
µs
4.0
1.3
4.7
0.6
4.0
0.6
µs
µs
µs
4.7
0
0.9
100
250
20 + 0.1CB
300
20 + 0.1CB
1000
ns
20 + 0.1CB
300
20 + 0.1CB
1000
_______________________________________________________________________________________
µs
ns
ns
3.3V Spread-Spectrum EconOscillator
(VCC = 2.7V to 3.6V, TA = -40°C to +85°C.)
PARAMETER
Setup Time for STOP
SYMBOL
tSU:STO
Capacitive Load for Each Bus
Line
CB
EEPROM Write Cycle Time
tWR
Input Capacitance
CONDITIONS
MIN
Fast mode
0.6
Standard mode
4.0
TYP
UNITS
µs
(Note 16)
CI
MAX
400
pF
10
ms
5
pF
NONVOLATILE MEMORY CHARACTERISTICS
(VCC = 2.7V to 3.6V)
PARAMETER
EEPROM Writes
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Note 12:
Note 13:
Note 14:
Note 15:
Note 16:
Note 17:
Note 18:
SYMBOL
CONDITIONS
+70°C
MIN
10,000
TYP
MAX
UNITS
All voltages are referenced to ground.
DAC and OFFSET register settings must be configured to maintain the master oscillator frequency within this range.
Correct operation of the device is not guaranteed if these limits are exceeded.
This is the absolute accuracy of the master oscillator frequency at the default settings.
This is the change that is observed in master oscillator frequency with changes in voltage from nominal voltage at
TA = +25°C.
This is the percentage frequency change from the +25°C frequency due to temperature at VCC = 3.3V. The maximum temperature change varies with the master oscillator frequency setting. The minimum occurs at the default master oscillator frequency (fdefault). The maximum occurs at the extremes of the master oscillator frequency range (33.3MHz or 66.6MHz).
The dither deviation of the master oscillator frequency is unidirectional and lower than the undithered frequency.
The integral nonlinearity of the frequency is a measure of the deviation from a straight line drawn between the two endpoints (fosc(MIN) to fosc(MAX)) of the range. The error is in percentage of the span.
This is true when the prescaler = 1.
Frequency settles faster for small changes in value. During a change, the frequency transitions smoothly from the original
value to the new value.
This indicates the time elapsed between power-up and the output becoming active. An on-chip delay is intentionally
introduced to allow the oscillator to stabilize. tstab is equivalent to approximately 512 master clock cycles and therefore
depends on the programmed clock frequency.
Output voltage swings can be impaired at high frequencies combined with high output loading.
A fast-mode device can be used in a standard-mode system, but the requirement tSU:DAT > 250ns must then be met.
This is automatically the case if the device does not stretch the LOW period of the SCL signal. If such a device does
stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line at least tR MAX + tSU:DAT =
1000ns + 250ns = 1250ns before the SCL line is released.
After this period, the first clock pulse is generated.
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to as the VIH MIN of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
The maximum tHD:DAT need only be met if the device does not stretch the LOW period (tLOW) of the SCL signal.
CB—total capacitance of one bus line, timing referenced to 0.9 x VCC and 0.1 x VCC.
Typical frequency shift due to aging is ±0.5%. Aging stressing includes Level 1 moisture reflow preconditioning (24hr
+125°C bake, 168hr 85°C/85%RH moisture soak, and three solder reflow passes +240 +0/-5°C peak) followed by 1000hr
max VCC biased 125°C HTOL, 1000 temperature cycles at -55°C to +125°C, 96hr 130°C/85%RH/3.6V HAST and 168hr
121°C/2 ATM Steam/Unbiased Autoclave.
tstab is the time required after exiting power-down to the beginning of output oscillations. In addition, a delay of tDACstab
is required before the frequency will be within its specified tolerance.
_______________________________________________________________________________________
5
DS1086L
AC ELECTRICAL CHARACTERISTICS—2-WIRE INTERFACE (continued)
Typical Operating Characteristics
(VCC = 3.3V, TA = 25°C, unless otherwise noted.)
SUPPLY CURRENT vs.
MASTER OSCILLATOR FREQUENCY
6
5
4.7pF LOAD
3
6
fO = 33.3MHz
PRESCALER = 1
15pF LOAD
4
2
PRESCALER = 1
-15
MASTER OSCILLATOR FREQUENCY PERCENT
CHANGE vs. SUPPLY VOLTAGE
fO = 66MHz
0.1
0
-0.1
fO = 50MHz
-0.2
fO = 33.3MHz
60
fO = 33.3MHz
-0.25
-0.50
fO = 50MHz
-0.75
fO = 66MHz
3.6
54
fO = 66MHz
53
52
fO = 50MHz
fO = 33.3MHz
PRESCALER = 1
50
-40
SUPPLY VOLTAGE (V)
-15
10
35
60
85
TEMPERATURE (°C)
-40
-15
10
DUTY CYCLE (%)
DS1086L toc07
54
fO = 66MHz
53
52
fO = 50MHz
51
fO = 33.3MHz
PRESCALER = 1
2.7
3.0
3.3
35
TEMPERATURE (°C)
DUTY CYCLE vs. SUPPLY VOLTAGE
55
3.6
SUPPLY VOLTAGE (V)
6
1000
DUTY CYCLE vs. TEMPERATURE
51
PRESCALER = 1
15pF LOAD
-1.50
3.3
100
55
0
-1.25
-0.5
3.0
10
PRESCALER
-1.00
PRESCALER = 1
2.7
fO = 50MHz
15pF LOAD
1
85
DS1086L toc05
0.25
-0.3
-0.4
35
DUTY CYCLE (%)
0.2
10
0.50
PERCENT CHANGE (%)
0.3
2
MASTER OSCILLATOR FREQUENCY PERCENT
CHANGE vs. TEMPERATURE
DS1086L toc04
0.4
3
TEMPERATURE (°C)
MASTER FREQUENCY (MHz)
0.5
4
0
-40
33 36 39 42 45 48 51 54 57 60 63 66
5
1
3
1
DS1086L toc03
DS1086L toc02
fO = 50MHz
5
6
DS1086L toc06
4
8
7
7
SUPPLY CURRENT (mA)
15pF LOAD
7
fO = 66MHz
9
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
8
SUPPLY CURRENT vs. PRESCALER
SUPPLY CURRENT vs. TEMPERATURE
10
DS1086L toc01
9
PERCENT CHANGET (%)
DS1086L
3.3V Spread-Spectrum EconOscillator
_______________________________________________________________________________________
60
85
3.3V Spread-Spectrum EconOscillator
POWER-DOWN CURRENT vs.
SUPPLY VOLTAGE
1.6
1.5
1.4
1.3
1.2
1.62
1.1
1.60
1.58
1.56
1.54
1.52
1.50
1.48
1.46
1.0
1.44
3.0
3.3
3.6
-40
-15
10
35
60
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY CURRENT WITH OUTPUT
DISABLED vs. SUPPLY VOLTAGE
SUPPLY CURRENT WITH OUTPUT
DISABLED vs. TEMPERATURE
2.7
DS1086L toc10
4.0
3.5
2.6
SUPPLY CURRENT (mA)
3.0
2.5
2.0
1.5
1.0
85
DS1086L toc11
2.7
SUPPLY CURRENT (mA)
DS1086L toc09
1.64
POWER-DOWN CURRENT (μA)
1.7
POWER-DOWN CURRENT (μA)
POWER-DOWN CURRENT vs. TEMPERATURE
DS1086L toc08
1.8
2.5
2.4
2.3
0.5
fO = 66MHz
fO = 66MHz
0
2.2
2.7
3.0
3.3
SUPPLY VOLTAGE (V)
3.6
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
7
DS1086L
Typical Operating Characteristics (continued)
(VCC = 3.3V, TA = 25°C, unless otherwise noted.)
3.3V Spread-Spectrum EconOscillator
PIN
NAME
1
OUT
2
SPRD
3
VCC
4
GND
FUNCTION
Oscillator Output. The output frequency is determined by the OFFSET, DAC, and prescaler registers.
Dither Enable. When the pin is high, the dither is enabled. When the pin is low, the dither is disabled.
Power Supply
Ground
5
OE
Output Enable. When the pin is high, the output buffer is enabled. When the pin is low, the output is
disabled but the master oscillator is still on.
6
PDN
Power-Down. When the pin is high, the master oscillator is enabled. When the pin is low, the master
oscillator is disabled (power-down mode).
7
SDA
2-Wire Serial Data. This pin is for serial data transfer to and from the device. The pin is open drain and
can be wire-ORed with other open-drain or open-collector interfaces.
8
SCL
2-Wire Serial Clock. This pin is used to clock data into the device on rising edges and clock data out on
falling edges.
MAXIMUM THERMAL VARIATION vs.
MASTER OSCILLATOR FREQUENCY
SPECTRUM COMPARISON
(12OkHz BW, SAMPLE DETECT)
NO
SPREAD
2%
-20
3%
2%
SUPPLY CURRENT (mA)
POWER SPECTRUM (dBm)
0.5%
8%
DS1086L fig01
0
-10
DS1086L fig02
DS1086L
Pin Description
-30
-40
-50
-60
1%
0
-1%
-2%
-3%
-70
fo = 50MHz
DITHER RATE = fo/4096
-80
-4%
-5%
-90
43
45
47
49
51
33 36 39 42 45 48 51 54 57 60 63 66
53
MASTER FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 2. Temperature Variation Over Frequency
Figure 1. Clock Spectrum Dither Comparison
Stand-Alone Mode
Processor-Controlled Mode
VCC
μP
4.7kΩ
DITHERED 260kHz TO
133MHz OUTPUT
VCC
XTL1/OSC1
XTL2/OSC2
SCL
OUT
SDA
SPRD
VCC
GND
DECOUPLING CAPACITORS
(0.1μF and 0.01μF)
8
4.7kΩ
DS1086L
PDN
OE
VCC
2-WIRE
INTERFACE
VCC
DITHERED 130kHz TO
66.6MHz OUTPUT
VCC
N.C.
OUT
SCL*
SPRD
SDA*
VCC
DS1086L
GND
PDN
OE
DECOUPLING CAPACITORS
(0.1μF and 0.01μF)
*SDA AND SCL CAN BE CONNECTED DIRECTLY HIGH IF THE DS1086L NEVER NEEDS
TO BE PROGRAMMED IN-CIRCUIT, INCLUDING DURING PRODUCTION TESTING.
_______________________________________________________________________________________
3.3V Spread-Spectrum EconOscillator
DS1086L
VCC
VCC
SDA
SCL
2-WIRE
INTERFACE
EEPROM CONTROL
REGISTERS
DS1086L
DAC
DAC
OFFSET
ADDR
RANGE
FREQUENCY
CONTROL VOLTAGE
PRESCALER
VOLTAGE-CONTROLLED
OSCILLATOR
PDN
MASTER
OSCILLATOR
OUTPUT
DITHER
CONTROL
PRESCALER
BY 1, 2, 4...256
OUT
OE
SPRD
GND
TRIANGLE WAVE
GENERATOR
DITHER SIGNAL
Figure 3. Block Diagram
Detailed Description
A block diagram of the DS1086L is shown in Figure 3.
The internal master oscillator generates a square wave
with a 33.3MHz to 66.6MHz frequency range. The frequency of the master oscillator can be programmed
with the DAC register over a two-to-one range in 5kHz
steps. The master oscillator range is larger than the
range possible with the DAC step size, so the OFFSET
register is used to select a smaller range of frequencies
over which the DAC spans. The prescaler can then be
set to divide the master oscillator frequency by 2 x
(where x equals 0 to 8) before routing the signal to the
output (OUT) pin.
A programmable triangle-wave generator injects an offset element into the master oscillator to dither its output
0.5%, 1%, 2%, 4%, or 8%. The dither magnitude is controlled by the JS2, JS1, and JS0 bits in the PRESCALER
word and enabled with the SPRD pin. Futhermore, the
dither rate is controlled by the JS4 and JS3 bits in the
PRESCALER word and determines the frequency of the
dither. The maximum spectral attenuation occurs when
the prescaler is set to 1 and is reduced by 2.7dB for
every factor of 2 that is used in the prescaler. This hap-
pens because the prescaler’s divider function tends to
average the dither in creating the lower frequency.
However, the most stringent spectral emission limits are
imposed on the higher frequencies where the prescaler
is set to a low divider ratio.
The external control input, OE, gates the clock output
buffer. The PDN pin disables the master oscillator and
turns off the clock output for power-sensitive applications*. On power-up, the clock output is disabled until
power is stable and the master oscillator has generated
512 clock cycles. Both controls feature a synchronous
enable that ensures there are no output glitches when
the output is enabled.
The control registers are programmed through a 2-wire
interface and are used to determine the output frequency and settings. Once programmed into EEPROM,
since the register settings are NV, the settings only
need to be reprogrammed if it is desired to reconfigure
the device.
*The power-down command must persist for at least two output frequency cycles plus 10µs for deglitching purposes.
_______________________________________________________________________________________
9
DS1086L
3.3V Spread-Spectrum EconOscillator
Table 1. Register Summary
REGISTER
ADDR
MSB
PRESCALER
PRESCALER
DAC (MSB)
DAC (LSB)
OFFSET
ADDR
RANGE
WRITE EE
02h
—
08h
—
0Eh
0Dh
37h
3Fh
JS4
P1
b9
b1
X1
X1
XX
BINARY
JS3
P0
b8
b0
X1
X1
XX
JS2
XX
b7
X0
X1
X1
XX
JS1
JS0
XX
XX
b6
b5
X0
X0
b4
b3
X1
WC
b4
b3
NO DATA
LO/HiZ
XX
b4
X0
b2
A2
b2
P3
XX
b3
X0
b1
A1
b1
LSB
FACTORY
DEFAULT
ACCESS
P2
XX
b2
X0
b0
A0
b0
0110000 0
00XXXXX
01111101b
00000000b
111- ----b
11110000b
xxx- - - - - b
R/W
R/W
R/W
R/W
R/W
R/W
R
—
—
X0 = Don’t care, reads as zero.
X1 = Don’t care, reads as one.
XX = Don’t care, reads indeterminate.
X = Don’t care.
Table 2. Offset Settings
See the Example Frequency Calculations section for a
more in-depth look at using the registers.
OFFSET
FREQUENCY RANGE (MHz)
OS - 6
30.74 to 35.86
OS - 5
33.30 to 38.42
OS - 4
35.86 to 40.98
OS - 3
38.42 to 43.54
OS - 2
40.98 to 46.10
PRESCALER (02h)
OS - 1
43.54 to 48.66
The PRESCALER word is a two-byte value containing
control bits for the prescaler (P3 to P0), output control
(Lo/HiZ), the jitter rate (JS4 to JS3), as well as control
bits for the jitter percentage (JS2 to JS0). The
PRESCALER word is read and written using two-byte
reads and writes beginning at address 02h.
JS4 to JS3: Jitter Rate. This is the frequency of the triangle wave generator and the modulation frequency
that the output is dithered. It can be programmed to the
master oscillator frequency, fOSC, divided by either
8192, 4096, or 2048.
OS*
46.10 to 51.22
OS + 1
48.66 to 53.78
OS + 2
51.22 to 56.34
OS + 3
53.78 to 58.90
OS + 4
56.34 to 61.46
OS + 5
58.90 to 64.02
OS + 6
61.46 to 66.58
*Factory default setting. OS is the integer value of the five LSBs
of the RANGE register.
The output frequency is determined by the following
equation:
fOUTPUT =
________________Register Definitions
The DS1086L registers are used to program the output
frequency, dither percent, dither rate, and 2-wire
address. Table 1 shows a summary of the registers and
detailed descriptions follow below.
JS4
JS3
JITTER RATE
0
0
fOSC/8192
0
1
fOSC/4096 (default)
1
0
fOSC/2048
(MIN FREQUENCY OF SELECTED OFFSET RANGE)
+ (DAC VALUE × 5 kHz STEP SIZE)
PRESCALER
where: min frequency of selected OFFSET range is the
lowest frequency (shown in Table 2 for the corresponding offset).
DAC value is the value of the DAC register (0 to 1023).
Prescaler is the value of 2x where x = 0 to 8.
10
______________________________________________________________________________________
3.3V Spread-Spectrum EconOscillator
JS2
JS1
JS0
JITTER %
0
0
0
0.5
0
0
1
1
0
1
0
2
1
0
0
4
1
1
1
8
required to program new master oscillator frequencies
shown in Table 2. The read-only backup is important
because the offset register is EEPROM and is likely to
be overwritten.
ADDR (0Dh)
Lo/HiZ: Output Low or High-Z. This bit determines the
state of the output pin when the device is in powerdown mode or when the output is disabled. If Lo/HiZ =
0, the output is HiZ when in power-down or disabled. If
Lo/HiZ = 1, the output is held low when in power-down
or disabled.
P3 to P0: Prescaler Divider. These bits divide the
master oscillator frequency by 2x, where x is P3 to P0
and can be from 0 to 8. Any prescaler value entered
greater than 8 decodes as 8.
DAC (08h)
B9 to B0: DAC Setting. The DAC word sets the master
oscillator frequency to a specific value within the current offset range. Each step of the DAC changes the
master oscillator frequency by 5kHz. The DAC word is
read and written using two-byte reads and writes
beginning at address 08h.
WC: EEPROM Write Control Bit. The WC bit
enables/disables the automatic writing of registers to
EEPROM. This prevents EEPROM wear out and eliminates the EEPROM write cycle time. If WC = 0 (default),
register writes are automatically written to EEPROM. If
WC = 1, register writes are stored in SRAM and only
written into EEPROM when the user sends a WRITE EE
command. If power is cycled to the device, then the
last value stored in EEPROM is recalled. WC = 1 is
ideal for applications that frequently modify the frequency/registers.
Regardless of the value of the WC bit, the value of the
ADDR register is always written immediately to EEPROM.
A2 to A0: Device Address Bits. These bits determine
the 2-wire slave address of the device. They allow up to
eight devices to be attached to the same 2-wire bus
and to be addressed individually.
WRITE EE Command (3Fh)
This command can be used when WC = 1 (see the WC
bit in ADDR register) to transfer all registers from SRAM
into EEPROM. The time required to store the values is
one EEPROM write cycle time. This command is not
needed if WC = 0.
OFFSET (0Eh)
B4 to B0: Offset. This value selects the master oscillator frequency range that can be generated by varying
the DAC word. Valid frequency ranges are shown in
Table 2. Correct operation of the device is not guaranteed for values of OFFSET not shown in the table.
The default offset value (OS) is factory trimmed and
can vary from device to device. Therefore, to change
frequency range, OS must be read so the new offset
value can be calculated relative to the default. For
example, to generate a master oscillator frequency
within the largest range (61.4MHz to 66.6MHz), Table 2
indicates that the OFFSET must be programmed to OS
+ 6. This is done by reading the RANGE register and
adding 6 to the value of bits B4 to B0. The result is then
written into bits B4 to B0 of the OFFSET register.
Additional examples are provided in the Example
Frequency Calculations section.
RANGE (37h)
B4 to B0: Range: This read-only, factory programmed
value is a copy of the factory default offset (OS). OS is
______________________________________________________________________________________
11
DS1086L
JS2 to JS0: Jitter Percentage. These three bits select
the amount of jitter in percent. The SPRD pin must be a
logic high for the jitter to be enabled. Bit combinations
not shown are reserved.
DS1086L
3.3V Spread-Spectrum EconOscillator
Example Frequency Calculations
Example #1: Calculate the register values needed to
generate a desired output frequency of 11.0592MHz.
Since the desired frequency is not within the valid master oscillator range of 33.3MHz to 66.6MHz, the
prescaler must be used. Valid prescaler values are 2x
where x equals 0 to 8 (and x is the value that is programmed into the P3 to P0 bits of the PRESCALER register). Equation 1 shows the relationship between the
desired frequency, the master oscillator frequency, and
the prescaler.
f
fDESIRED = MASTER OSCILLATOR
prescaler
fMASTER OSCILLATOR
=
(1)
2X
By trial and error, x is incremented from 0 to 8 in
Equation 2, finding values of x that yield master oscillator
frequencies within the range of 33.3MHz to 66.6MHz.
Equation 2 shows that a prescaler of 4 (x = 2) and a
master oscillator frequency of 44.2368MHz generates
our desired frequency. Writing 0080h to the
PRESCALER register sets the PRESCALER to 4. Be
aware that other settings also reside in the PRESCALER
register.
fMASTER OSCILLATOR = fDESIRED x prescaler = fDESIRED x 2X
fMASTER OSCILLATOR = 11.0592MHz x 22 = 44.2368MHz
(2)
Once the target master oscillator frequency has been
calculated, the value of offset can be determined.
Using Table 2, 44.2368MHz falls within both OS - 1 and
OS - 2. However, choosing OS - 1 would be a poor
choice since 44.2368MHz is so close to OS - 1’s minimum frequency. On the other hand, OS - 2 is ideal
since 44.2368MHz is close to the center of
OS - 2’s frequency span. Before the OFFSET register
can be programmed, the default value of offset (OS)
must be read from the RANGE register (last five bits). In
this example, 12h (18 decimal) was read from the
RANGE register. OS - 2 for this case is 10h (16 decimal). This is the value that is written to the OFFSET register.
Finally, the two-byte DAC value needs to be determined. Since OS - 2 only sets the range of frequencies,
the DAC selects one frequency within that range as
shown in Equation 3.
Valid values of DAC are 0 to 1023 (decimal) and 5kHz
is the step size. Equation 4 is derived from rearranging
Equation 3 and solving for the DAC value.
DAC VALUE =
(fMASTER OSCILLATOR −
MIN FREQUENCY OF SELECTED
OFFSET RANGE)
5kHz STEP SIZE
(44.2368MHz − 41.0MHz)
5kHz STEP SIZE
= 647.36 ≈ 647 (decimal)
DAC VALUE =
Since the two-byte DAC register is left justified, 647 is
converted to hex (0287h) and bit-wise shifted left six
places. The value to be programmed into the DAC register is A1C0h.
In summary, the DS1086L is programmed as follows:
PRESCALER = 0080h
OFFSET = OS - 2 or 10h (if range was read as 12h)
DAC = A1C0h
Notice that the DAC value was rounded. Unfortunately,
this means that some error is introduced. To calculate
how much error, a combination of Equation 1 and
Equation 3 is used to calculate the expected output frequency. See Equation 5.
(MIN FREQUENCY OF SELECTED OFFSET
RANGE) + (DAC VALUE x 5kHz STEP SIZE)
fOUTPUT =
prescaler
(41.0MHz) + (647 x 5kHz)
fOUTPUT =
=
4
44.235MHz
= 11.05875MHz
4
fMASTER OSCILLATOR = (MIN FREQUENCY OF SELECTED OFFSET
RANGE) + (DAC value x 5kHz)
12
(4)
(3)
______________________________________________________________________________________
(5)
3.3V Spread-Spectrum EconOscillator
DS1086L
SDA
MSB
SLAVE ADDRESS
R/W
DIRECTION
BIT
ACKNOWLEDGEMENT
SIGNAL FROM RECEIVER
ACKNOWLEDGEMENT
SIGNAL FROM RECEIVER
SCL
1
2
6
7
8
9
1
2
3–7
8
ACK
START
CONDITION
9
ACK
REPEATED IF MORE BYTES
ARE TRANSFERRED
STOP
CONDITION
OR REPEATED
START
CONDITION
Figure 4. 2-Wire Data Transfer Protocol
The expected output frequency is not exactly equal to the
desired frequency of 11.0592MHz. The difference is
450Hz. In terms of percentage, Equation 6 shows that the
expected error is 0.004%. The expected error assumes
typical values and does not include deviations from the
typical as specified in the electrical tables.
%ERROREXPECTED =
%ERROREXPECTED =
fDESIRED − fEXPECTED
× 100
fDESIRED
(6)
11.0592MHz − 11.05875MHz
× 100
11.0592MHz
450Hz
=
× 100 = 0.004%
11.0592MHz
Example #2: Calculate the register values needed to
generate a desired output frequency of 50MHz.
Since the desired frequency is already within the valid
master oscillator frequency range, the prescaler is set
to divide by 1, and hence, PRESCALER = 0000h
(currently ignoring the other setting).
(7)
fMASTER OSCILLATOR = 50.0MHz x 20 = 50.0MHz
Finally, the DAC value is calculated as shown in
Equation 8.
(8)
DAC VALUE =
(50.0MHz − 48.6MHz)
= 280.00 (decimal)
5kHz STEP SIZE
The result is then converted to hex (0118h) and then
left-shifted, resulting in 4600h to be programmed into
the DAC register.
In summary, the DS1086L is programmed as follows:
PRESCALER = 0000h
OFFSET = OS + 1 or 13h (if RANGE was read as 12h)
DAC = 4600h
fOUTPUT
=
(48.6MHz) + (280 × 5kHz)
=
20
50.0MHz
= 50.0MHz
1
(9)
Since the expected output frequency is equal to the
desired frequency, the calculated error is 0%.
Next, looking at Table 2, OS + 1 provides a range of
frequencies centered around the desired frequency. To
determine what value to write to the OFFSET register,
the RANGE register must first be read. Assuming 12h
was read in this example, 13h (OS + 1) is written to the
OFFSET register.
______________________________________________________________________________________
13
DS1086L
3.3V Spread-Spectrum EconOscillator
MSB
LSB
1
1
A1
A0
R/W
DEVICE
ADDRESS
REA
D/W
DEVICE
IDENTIFIER
A2
IT
0
RIT
EB
1
Figure 5. Slave Address
SDA
tBUF
tHD:STA
tLOW
tR
tSP
tF
SCL
tHD:STA
STOP
tSU:STA
tHIGH
tSU:DAT
START
REPEATED
START
tSU:STO
tHD:DAT
Figure 6. 2-Wire AC Characteristics
_______2-Wire Serial Port Operation
2-Wire Serial Data Bus
The DS1086L communicates through a 2-wire serial
interface. A device that sends data onto the bus is
defined as a transmitter, and a device receiving data
as a receiver. The device that controls the message is
called a “master.” The devices that are controlled by
the master are “slaves.” A master device that generates
the serial clock (SCL), controls the bus access, and
generates the START and STOP conditions must control the bus. The DS1086L operates as a slave on the 2wire bus. Connections to the bus are made through the
open-drain I/O lines SDA and SCL.
The following bus protocol has been defined (see
Figures 4 and 6):
•
Data transfer can be initiated only when the bus is
not busy.
•
During data transfer, the data line must remain
stable whenever the clock line is HIGH. Changes
14
in the data line while the clock line is HIGH are
interpreted as control signals.
Accordingly, the following bus conditions have been
defined:
Bus not busy: Both data and clock lines remain HIGH.
Start data transfer: A change in the state of the data
line, from HIGH to LOW, while the clock is HIGH,
defines a START condition.
Stop data transfer: A change in the state of the data
line, from LOW to HIGH, while the clock line is HIGH,
defines the STOP condition.
Data valid: The state of the data line represents valid
data when, after a START condition, the data line is stable for the duration of the HIGH period of the clock signal. The data on the line must be changed during the
LOW period of the clock signal. There is one clock
pulse per bit of data.
Each data transfer is initiated with a START condition
and terminated with a STOP condition. The number of
data bytes transferred between START and STOP con-
______________________________________________________________________________________
3.3V Spread-Spectrum EconOscillator
2)
Data transfer from a slave transmitter to a master
receiver. The first byte (the slave address) is
transmitted by the master. The slave then returns
an acknowledge bit. Next follows a number of
data bytes transmitted by the slave to the master.
The master returns an acknowledge bit after all
received bytes other than the last byte. At the end
of the last received byte, a not acknowledge is
returned.
The master device generates all the serial clock pulses
and the START and STOP conditions. A transfer is
ended with a STOP condition or with a repeated START
condition. Since a repeated START condition is also the
beginning of the next serial transfer, the bus is not
released.
The DS1086L can operate in the following two modes:
Slave receiver mode: Serial data and clock are
received through SDA and SCL. After each byte is
received, an acknowledge bit is transmitted. START
and STOP conditions are recognized as the beginning
and end of a serial transfer. Address recognition is performed by hardware after reception of the slave
address and direction bit.
Slave transmitter mode: The first byte is received and
handled as in the slave receiver mode. However, in this
mode, the direction bit indicates that the transfer direction is reversed. Serial data is transmitted on SDA by
the DS1086L while the serial clock is input on SCL.
START and STOP conditions are recognized as the
beginning and end of a serial transfer.
Slave Address
Figure 5 shows the first byte sent to the device. It
includes the device identifier, device address, and the
R/W bit. The device address is determined by the
ADDR register.
Registers/Commands
See Table 1 for the complete list of registers/commands and Figure 7 for an example of using them.
__________Applications Information
Power-Supply Decoupling
To achieve the best results when using the DS1086L,
decouple the power supply with 0.01µF and 0.1µF
high-quality, ceramic, surface-mount capacitors.
Surface-mount components minimize lead inductance,
which improves performance, and ceramic capacitors
tend to have adequate high-frequency response for
decoupling applications. These capacitors should be
placed as close to pins 3 and 4 as possible.
Stand-Alone Mode
SCL and SDA cannot be left floating when they are not
used. If the DS1086L never needs to be programmed
in-circuit, including during production testing, SDA and
SCL can be tied high. The SPRD pin must be tied either
high or low.
______________________________________________________________________________________
15
DS1086L
ditions is not limited, and is determined by the master
device. The information is transferred byte-wise and
each receiver acknowledges with a ninth bit.
Within the bus specifications a standard mode (100kHz
clock rate) and a fast mode (400kHz clock rate) are
defined. The DS1086L works in both modes.
Acknowledge: Each receiving device, when
addressed, is obliged to generate an acknowledge
after the byte has been received. The master device
must generate an extra clock pulse that is associated
with this acknowledge bit.
A device that acknowledges must pull down the SDA
line during the acknowledge clock pulse in such a way
that the SDA line is stable LOW during the HIGH period
of the acknowledge-related clock pulse. Of course,
setup and hold times must be taken into account.
When the DS1086L EEPROM is being written to, it is
not able to perform additional responses. In this case,
the slave DS1086L sends a not acknowledge to any
data transfer request made by the master. It resumes
normal operation when the EEPROM operation is complete.
A master must signal an end of data to the slave by not
generating an acknowledge bit on the last byte that has
been clocked out of the slave. In this case, the slave
must leave the data line HIGH to enable the master to
generate the STOP condition.
Figures 4, 5, 6, and 7 detail how data transfer is
accomplished on the 2-wire bus. Depending upon the
state of the R/W bit, two types of data transfer are possible:
1) Data transfer from a master transmitter to a slave
receiver. The first byte transmitted by the master
is the slave address. Next follows a number of
data bytes. The slave returns an acknowledge bit
after each received byte.
DS1086L
3.3V Spread-Spectrum EconOscillator
TYPICAL 2-WIRE WRITE TRANSACTION
MSB
START
1
LSB
0
1
1
A2* A1* A0* R/W
DEVICE IDENTIFIER
DEVICE
ADDRESS
MSB
SLAVE
ACK
READ/
WRITE
b7
b5
b4
b3
B0h
START 1 0 1 1 0 0 0 0
b2
b1
b0
SLAVE
ACK
b7
LSB
b6
COMMAND/REGISTER ADDRESS
EXAMPLE 2-WIRE TRANSACTIONS (WHEN A0, A1, AND A2 ARE ZERO)
B0h
0Eh
SLAVE
SLAVE
A) SINGLE BYTE WRITE
START 1 0 1 1 0 0 0 0 ACK 0 0 0 0 1 1 1 0
ACK
-WRITE OFFSET REGISTER
B) SINGLE BYTE READ
-READ OFFSET REGISTER
MSB
LSB
b6
0Eh
SLAVE
SLAVE
00001110
ACK
ACK
C) TWO BYTE WRITE
-WRITE DAC REGISTER
B0h
08h
START 1 0 1 1 0 0 0 0 SLAVE 0 0 0 0 1 0 0 0 SLAVE
ACK
ACK
D) TWO BYTE READ
-READ DAC REGISTER
B0h
08h
START 1 0 1 1 0 0 0 0 SLAVE 0 0 0 0 1 0 0 0 SLAVE
ACK
ACK
b5
b4
b3
b2
b1
b0
SLAVE
ACK
STOP
DATA
DATA
OFFSET
SLAVE
ACK
STOP
DATA
B1h
REPEATED
START
10110001
SLAVE
ACK
OFFSET
MASTER
NACK
STOP
DATA
DATA
DAC MSB
SLAVE
ACK
DAC LSB
B1h
REPEATED
START
10110001
SLAVE
ACK
STOP
DATA
SLAVE
ACK
DAC MSB
DATA
MASTER
ACK
DAC LSB
MASTER
NACK
STOP
*THE ADDRESS DETERMINED BY A0, A1, AND A2 MUST
MATCH THE ADDRESS SET IN THE ADDR REGISTER.
Figure 7. 2-Wire Transactions
Chip Topology
TRANSISTOR COUNT: 9052
SUBSTRATE CONNECTED TO GROUND
Package Information
For the latest package outline information, go to
www.maxim-ic.com/DallasPackInfo.
Revision History
Pages changed at Rev 1: 10
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.