LTC6902
Multiphase Oscillator
with Spread Spectrum
Frequency Modulation
FEATURES
DESCRIPTIO
n
2-, 3- or 4-Phase Outputs The LTC 6902 is a precision, low power and easy-to-use
n
Optional Spread Spectrum Frequency Modulation oscillator that provides multiphase outputs in a small
for Improved EMC Performance package. The oscillator frequency is set by a single exter-
n
5kHz to 20MHz Frequency Range nal resistor (R ). The LTC6902 also provides an optional
SET
n
One External Resistor Sets the Frequency spread spectrum frequency modulation (SSFM) capability
n
One External Resistor Sets Percent Frequency that can be activated and controlled by an additional
Spreading external resistor (R ).
MOD
n
400m A Typical Supply Current, V = 3V, 1MHz
S
The LTC6902s master oscillator is controlled by the R
SET
n
Frequency Error 1.5% Max, 5kHz to 10MHz
resistor and has a range of 100kHz and 20MHz. In order
(T = 25 C)
A
to accommodate a wider output frequency range, a pro-
n
Frequency Error 2% Max, 5kHz to 10MHz
grammable divider (divide by 1, 10 or 100) is included.
(T = 0 C to 70 C)
A
The integrated programmable multiphase circuit pro-
n
40ppm/ C Temperature Stability
vides either 2-, 3- or 4-phase waveforms.
n
Fast Start-Up Time: 50m s to 1.5ms
n The LTC6902s SSFM capability modulates the oscillators
100W CMOS Output Driver
n frequency by a pseudorandom noise (PRN) signal to
Operates from a Single 2.7V to 5.5V Supply
n spread the oscillators energy over a wide frequency band.
Available in 10-Lead MS Package
This spreading decreases the peak electromagnetic radia-
U
tion level and improves electromagnetic compatibility
APPLICATIO S
(EMC) performance. The amount of frequency spreading
n
Switching Power Supply Clock Reference
is programmable by a single additional external resistor
n
Portable and Battery-Powered Equipment
(R ) and is disabled by grounding the MOD pin.
MOD
n
PDAs
, LTC and LT are registered trademarks of Linear Technology Corporation.
n
Cell Phones
n
Clocking Switched Capacitor Filters
TYPICAL APPLICATIO
Output Frequency Spectrum With and Without SSFM
0
500kHz, 4-Phase Clock with 20% Frequency Spreading
OUTPUT
SPECTRUM
5V
WITH SSFM
R 10k
20
MOD
0.1F
DISABLED
OUTPUT
R 10k
SET
SPECTRUM
40
WITH 20%
LTC6902
SPREADING
+
V SET
60
OPEN
DIV MOD
PH GND
80
OUT4
OUT1 OUT4
OUT3
OUT2 OUT3
OUT2
100
400 450 500 550 600
OUT1
6902 TA01
FREQUENCY (kHz) 6902 TA02
6902f
1
RELATIVE AMPLITUDE (dBm)
U
ULTC6902
UUW
ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO
(Note 1)
+
Supply Voltage (V ) to GND ........................0.3V to 6V
ORDER
Voltage On Any Pin
PART NUMBER
TOP VIEW
+
+
(Referred to GND) ......................... 0.3V to (V + 0.3V)
V 1 10 SET
LTC6902CMS
DIV 2 9 MOD
Operating Temperature Range (Note 9)
PH 3 8 GND
LTC6902IMS
OUT1 4 7 OUT4
LTC6902C .......................................... 40 C to 85 C
OUT2 5 6 OUT3
LTC6902I............................................ 40 C to 85 C
MS PACKAGE
MS PART MARKING
10-LEAD PLASTIC MSOP
Specified Temperature Range (Note 10)
T = 150 C, q = 250 C/W
JMAX JA
LTK2
LTC6902C .......................................... 40 C to 85 C
LTK3
LTC6902I............................................ 40 C to 85 C
Storage Temperature Range ................. 65 C to 150 C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Lead Temperature (Soldering, 10 sec).................. 300 C
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
+
temperature range, otherwise specifications are at T = 25 C. V = 2.7V to 5.5V, R = 5k, C = 5pF, Pin 3 (PH) = 0V (2-phase, M = 1)
A L L
unless otherwise specified. Pin 9 (MOD) is at 0V unless otherwise specified. R is defined as a resistor connected from the SET pin
SET
+ +
to the V pin. R is defined as a resistor connected from the MOD pin to the V pin.
MOD
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
+
D f Frequency Accuracy (Notes 2, 3) V = 5V 5kHz f 10MHz 0.5 1.5 %
OUT OUT
1kHz f 5kHz 2.0 %
OUT
10MHz f 20MHz l 3.0 4.0 %
OUT
5kHz f 10MHz, LTC6902C l 2.0 %
OUT
5kHz < f 10MHz, LTC6902I l 2.5 %
OUT
+
V = 2.7V 5kHz f 10MHz 0.5 1.5 %
OUT
1kHz f 5kHz 2.0 %
OUT
5kHz f 10MHz, LTC6902C l 2.0 %
OUT
10MHz, LTC6902I l 2.5 %
5kHz f
OUT
+
R Frequency Setting Resistor Range D f < 1.5%, V = 5V l 20 400 kW
SET OUT
+
D f < 1.5%, V = 2.7V l 20 400 kW
OUT
D f /D T Frequency Drift Over Temperature R = 63.2k l 0.004 %/ C
OUT SET
(Note 3)
+
D f /D V Frequency Drift Over Supply (Note 3) V = 2.7V to 5V, R = 63.2k l 0.04 0.12 %/V
OUT SET
Timing Jitter (Note 4) 20k R 400k
SET
+
Pin 2 = V (N = 100) 0.1 %
Pin 2 = Open (N = 10) 0.2 %
Pin 2 = 0V (N = 1) 0.6 %
Long-Term Stability of 300 ppm/ kHr
Output Frequency
+
Duty Cycle (Note 5) Pin 2 = V or Open (N = 100 or 10)
Pin 3 = 0V (2-Phase, M = 1) l 49.0 50.0 51.0 %
Pin 3 = Open (3-Phase, M = 3) l 32.3 33.3 34.3 %
+
Pin 3 = V (4-Phase, M = 4) l 49.0 50.0 51.0 %
Pin 2 = 0V (N = 1)
Pin 3 = 0V (2-Phase, M = 1) l 45.0 50.0 55.0 %
Pin 3 = Open (3-Phase, M = 3) l 32.3 33.3 34.3 %
+
Pin 3 = V (4-Phase, M = 4) l 49.0 50.0 51.0 %
6902f
2
U WWW