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PDF DS1087L Data sheet ( Hoja de datos )
| Número de pieza | DS1087L | |
| Descripción | Spread-Spectrum EconOscillator | |
| Fabricantes | Dallas Semiconductor | |
| Logotipo |  |
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Rev 1; 11/03
3.3V Spread-Spectrum EconOscillator
General Description
The DS1087L is a clock generator that produces a
spread-spectrum (dithered) square-wave output of fre-
quencies from 130kHz to 66.6MHz. The DS1087L is
shipped from the factory programmed at a specific fre-
quency and spread-spectrum percentage. The user still
has access to an internal frequency divider, selectable
2% or 4% dithered output, and programmable output
power-down/disable mode through a 2-wire program-
ming interface. All the device settings are stored in non-
volatile (NV) EEPROM allowing it to operate in
stand-alone applications. The DS1087L has power-
down and output-enable control pins for power-sensi-
tive applications.
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Printers
Copiers
PCs
Computer Peripherals
Cell Phones
Cable Modems
Applications
Features
♦ Factory Programmed Square-Wave Generator
from 130kHz to 66.6MHz
♦ No External Timing Components Required
♦ EMI Reduction
♦ 2.7V to 3.6V Supply
♦ User Programmable Down to 130kHz with Divider
(Dependent on Master Oscillator Frequency)
♦ 2% or 4% Selectable Dithered Output
♦ Glitchless Output-Enable Control
♦ 2-Wire Serial Interface
♦ Nonvolatile Settings
♦ Power-Down Mode
♦ Programmable Output Power-Down/Disable Mode
PART
DS1087LU-yxx
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
8 µSOP (118 mils)
Standard Frequency Options
PART
DS1087LU-202
DS1087LU-402
DS1087LU-210
DS1087LU-216
DS1087LU-266
DS1087LU-466
DS1087LU-yxx
FREQUENCY (MHz)
2.0480
2.0480
10.0
16.6
66.6
66.6
Fixed up to 66.6
SPREAD (%)
2
4
2
2
2
4
2 or 4
Custom frequencies and over 20 standard frequencies avail-
able, contact factory.
EconOscillator is a trademark of Dallas Semiconductor.
Typical Operating Circuits appear at end of data sheet.
TOP VIEW
Pin Configuration
OUT 1
SPRD 2
VCC 3
GND 4
DS1087L
8 SCL
7 SDA
6 PDN
5 OE
µSOP (118 mils)
______________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
3.3V Spread-Spectrum EconOscillator
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:
All voltages are referenced to ground.
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 dither deviation of the master oscillator frequency is unidirectional and lower than the undithered frequency.
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 depends
on the programmed master oscillator frequency.
Output voltage swings may 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 sig-
nal) 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 3 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, and 168hr 121°C/2 ATM Steam/Unbiased
Autoclave.
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
ACTIVE SUPPLY CURRENT
vs. TEMPERATURE
7.5
VCC = 3.3V
FREQUENCY = 66.6MHz
7.0 OE = PDN = VCC
6.5 15pF LOAD
6.0
8.2pF LOAD
5.5 4.7pF LOAD
UNLOADED
5.0
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
ACTIVE SUPPLY CURRENT
vs. VOLTAGE
8.0
FREQUENCY = 66.6MHz
7.0 OUTPUT UNLOADED
6.0 OE = PDN = VCC
5.0
4.0
3.0
2.0
1.0
0
2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6
VOLTAGE (V)
SUPPLY CURRENT vs. PRESCALER
7
OUTPUT UNLOADED
6
5
4
3
3.6V
2 3.3V
2.7V
1
0
1 10 100 1000
PRESCALER (DECIMAL)
_____________________________________________________________________ 5
5 Page 
3.3V Spread-Spectrum EconOscillator
SDA
tBUF
SCL
STOP START
tLOW
tHD:STA
Figure 5. 2-Wire AC Characteristics
tR tF
tHD:STA
tHD:DAT
tHIGH
tSU:DAT
tSU:STA
REPEATED
START
tSP
tSU:STO
TYPICAL 2-WIRE WRITE TRANSACTION
MSB
LSB MSB
LSB MSB
LSB
START
1
0
1
1
A2*
A1*
A0* R/W
SLAVE
ACK
b7
b6
b5
b4
b3
b2
b1
b0
SLAVE
ACK
b7
b6
b5
b4
b3
b2
b1
b0
SLAVE
ACK
STOP
DEVICE IDENTIFIER
DEVICE READ/
ADDRESS WRITE
COMMAND/REGISTER ADDRESS
DATA
EXAMPLE 2-WIRE TRANSACTIONS (WHEN A0, A1, AND A2 ARE ZERO)
B0h
A) SINGLE BYTE WRITE
-WRITE PRESCALER
START 1 0 1 1 0 0 0 0
SLAVE
ACK
REGISTER TO 128
02h
00000010
SLAVE
ACK
DATA
10000000
SLAVE
ACK
STOP
B) SINGLE BYTE READ
-READ PRESCALER
REGISTER
B0h 02h
B1h DATA
START 1 0 1 1 0 0 0 0
SLAVE
ACK
00000010
SLAVE
ACK
REPEATED
START
10110001
SLAVE
ACK
10000000
MASTER
NACK
STOP
*THE ADDRESS DETERMINED BY A0, A1, AND A2 MUST
MATCH THE ADDRESS SET IN THE ADDR REGISTER.
Figure 6. 2-Wire Transactions
Application Information
Power-Supply Decoupling
To achieve the best results when using the DS1087L,
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 the VCC and GND pins as possible.
Stand-alone Mode
SCL and SDA cannot be left floating even in stand-
alone mode. If the DS1087L never needs to be pro-
grammed in-circuit, including during production
testing, SDA and SCL can be wired high.
____________________________________________________________________ 11
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| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet DS1087L.PDF ] | |
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