LTC6908-1/LTC6908-2
Resistor Set SOT-23 Oscillator with
Spread Spectrum Modulation
FEATURES DESCRIPTION
n
LTC6908-1: Complementary Outputs (0/180) The LTC 6908 is an easy-to-use precision oscillator that
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LTC6908-2: Quadrature Outputs (0/90) provides 2-outputs, shifted by either 180 or 90. The
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50kHz to 10MHz Frequency Range oscillator frequency is programmed by a single external
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One External Resistor Sets the Frequency resistor (R ) and spread spectrum frequency modula-
SET
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Optional Spread Spectrum Frequency Modulation tion (SSFM) can be activated for improved electromag-
for Improved EMC Performance netic compatibility (EMC) performance.
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10% Frequency Spreading
The LTC6908 operates with a single 2.7V to 5.5V supply
+
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400A Supply Current Typical (V = 5V, 50kHz)
and provides rail-to-rail, 50% duty cycle square wave out-
+
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Frequency Error 1.5% Max (T = 25C, V = 3V)
A
puts. A single resistor from 10k to 2M is used to select an
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40ppm/C Temperature Stability
oscillator frequency from 50kHz to 10MHz (5V supply).
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Fast Start-Up Time: 260s Typical (1MHz)
The oscillator can be easily programmed using the simple
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Outputs Muted Until Stable
formula outlined below:
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Operates from a Single 2.7V to 5.5V Supply
n f =10MHz 10k/R
Available in Low Profile (1mm) ThinSOT and DFN OUT SET
(2mm 3mm) Packages
The LTC6908s SSFM capability modulates the output
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AEC-Q100 Qualified for Automotive Applications
frequency by a pseudorandom noise (PRN) signal to
decrease the peak electromagnetic radiation level and
improve EMC performance. The amount of frequency
APPLICATIONS
spreading is fixed at 10% of the center frequency. When
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Switching Power Supply Clock Reference
SSFM is enabled, the rate of modulation is selected by
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Portable and Battery-Powered Equipment
the user. The three possible modulation rates are f /16,
OUT
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Precision Programmable Oscillator
f /32 and f /64.
OUT OUT
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Charge Pump Driver
All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION
150kHz to 30MHz Output
Frequency Spectrum
2.25MHz, 2.5V/8A Step-Down Regulator
(9kHz Res BW)
V
IN 0
2.8V TO 5.5V C
IN SSFM DISABLED
100F 10
SV TRACK PV
IN IN
0.2H
C V
OUT
BYP
20
+
R SW 2.5V
V OUT1 T
8A
LTC3418
2.2M 30
41.2k
0.1F LTC6908-1
PGOOD
C
OUT
40
GND OUT2
PGND 100F
RUN/SS
2 0
44.2k
I SGND
1000pF TH
SSFM ENABLED
4.99k SYNC/MODE V
SET MOD 10
FB
690812 TA01a
820pF
20
4.32k
f = 10MHz 10k/R
OUT SET
30
2k
40
150kHz 30MHz
FREQUENCY
(FUNDAMENTAL AND HARMONICS SHOWN)
690812 TA01b
Rev C
1
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OUTPUT (dBc) OUTPUT (dBc)LTC6908-1/LTC6908-2
(Note 1)
ABSOLUTE MAXIMUM RATINGS
+
Total Supply Voltage (V to GND) ................................6V Specified Temperature Range (Note 3)
Maximum Voltage on any Pin LTC6908CS6-1/LTC6908CS6-2 ................ 0C to 70C
+
(GND 0.3V) V (V + 0.3V) LTC6908IS6-1/LTC6908IS6-2 ..............40C to 85C
PIN
Output Short Circuit Duration .......................... Indefinite LTC6908HS6-1/LTC6908HS6-2 ......... 40C to 125C
Operating Temperature Range (Note 2) LTC6908CDCB-1/LTC6908CDCB-2 .......... 0C to 70C
LTC6908CS6-1/LTC6908CS6-2 ............40C to 85C LTC6908IDCB-1/LTC6908IDCB-2 .........40C to 85C
LTC6908IS6-1/LTC6908IS6-2 ..............40C to 85C Storage Temperature Range (S6) ........... 65C to 150C
LTC6908HS6-1/LTC6908HS6-2 ......... 40C to 125C Storage Temperature Range (DCB) ........ 65C to 125C
LTC6908CDCB-1/LTC6908CDCB-2 ......40C to 85C Lead Temperature (Soldering, 10sec)....................300C
LTC6908IDCB-1/LTC6908IDCB-2 .........40C to 85C
PIN CONFIGURATION
TOP VIEW
6 5 4
TOP VIEW
+
V 1 6 OUT1
7
GND 2 5 OUT2
SET 3 4 MOD
S6 PACKAGE
1 2 3
6-LEAD PLASTIC TSOT-23
T = 150C, = 230C/W
JMAX JA
DCB PACKAGE
6-LEAD (2mm 3mm) PLASTIC DFN
T = 125C, = 64C/W
JMAX JA
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC6908CDCB-1#TRMPBF LTC6908CDCB-1#TRPBF LBXZ 6-Lead (2mm 3mm) Plastic DFN 0C to 70C
LTC6908IDCB-1#TRMPBF LTC6908IDCB-1#TRPBF LBXZ 6-Lead (2mm 3mm) Plastic DFN 40C to 85C
LTC6908CDCB-2#TRMPBF LTC6908CDCB-2#TRPBF LBYB 6-Lead (2mm 3mm) Plastic DFN 0C to 70C
LTC6908IDCB-2#TRMPBF LTC6908IDCB-2#TRPBF LBYB 6-Lead (2mm 3mm) Plastic DFN 40C to 85C
LTC6908CS6-1#TRMPBF LTC6908CS6-1#TRPBF LTBYC 6-Lead Plastic TSOT-23 0C to 70C
LTC6908IS6-1#TRMPBF LTC6908IS6-1#TRPBF LTBYC 6-Lead Plastic TSOT-23 40C to 85C
LTC6908HS6-1#TRMPBF LTC6908HS6-1#TRPBF LTBYC 6-Lead Plastic TSOT-23 40C to 125C
LTC6908CS6-2#TRMPBF LTC6908CS6-2#TRPBF LTBYD 6-Lead Plastic TSOT-23 0C to 70C
LTC6908IS6-2#TRMPBF LTC6908IS6-2#TRPBF LTBYD 6-Lead Plastic TSOT-23 40C to 85C
LTC6908HS6-2#TRMPBF LTC6908HS6-2#TRPBF LTBYD 6-Lead Plastic TSOT-23 40C to 125C
Rev C
2
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SET MOD
+
V OUT2
GND OUT1