Datasheet LTC6902 (Analog Devices) - 5
| Manufacturer | Analog Devices |
| Description | Multiphase Oscillator with Spread Spectrum Frequency Modulation |
| Pages / Page | 16 / 5 — TYPICAL PERFOR A CE CHARACTERISTICS. Output Operating at 20MHz,. Output … |
| File Format / Size | PDF / 213 Kb |
| Document Language | English |
TYPICAL PERFOR A CE CHARACTERISTICS. Output Operating at 20MHz,. Output Operating at 10MHz,. VS = 5V. VS = 3V. QUICK DESIG GUIDE
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LTC6902
W U TYPICAL PERFOR A CE CHARACTERISTICS Output Operating at 20MHz, Output Operating at 10MHz, VS = 5V VS = 3V
V+ = 5V, RSET = 10k, CL = 10pF V+ = 3V, RSET = 20k, CL = 10pF 1V/DIV 1V/DIV 0V 0V 12.5ns/DIV 69012 G06 25ns/DIV 69012 G07
U QUICK DESIG GUIDE
V+ RMOD 0.1µF RSET LTC6902 MHz 10 k 20 f = • Ω ; kHz 5 f 2 MHz OUT OUT 0 V+ SET N • M RSET ≤ ≤ DIV DIV MOD PH PH GND R Spreading Percentage SET = 20 • OUT1 OUT4 OUT4 RMOD OUT2 OUT3 OUT3 OUT2 OUT1 6902 F01
Figure 1. Typical Application with Design Equation Step 1. Select Multiphase Mode, Setting M DIVIDER SETTING FREQUENCY RANGE (fOUT • M)
By selecting the multiphase mode, a division parameter M N = 1 Connect DIV Pin to GND 2MHz to 20MHz is also chosen: N = 10 Leave DIV Open 200kHz to 2MHz N = 100 Connect DIV Pin to V+ < 200kHz 2-Phase: Connect PH Pin to GND M = 1 Note: The frequency range numbers are for a 5V supply where a 20MHz 3-Phase: Leave PH Open M = 3 output is the maximum frequency supported. For low supply applications 4-Phase: Connect PH Pin to V+ M = 4 (2.7V ≤ V+ ≤ 4V), the maximum rated output frequency is 10MHz and all of the above numbers should be halved.
Step 2. Choosing Programmable Divider Setting N
B. For constant frequency applications where frequency A. For applications using spread spectrum frequency accuracy is the primary specification: modulation (SSFM) or applications that are constant fre-
DIVIDER SETTING FREQUENCY RANGE (f
quency where low clock jitter is the primary specification:
OUT • M)
N = 1 Connect DIV Pin to GND > 500kHz* N = 10 Leave DIV Open 50kHz to 500kHz N = 100 Connect DIV Pin to V+ < 50kHz *The maximum frequency (fOUT • M) is 20MHz for 5V applications and is 10MHz for low supply applications (2.7V ≤ V+ ≤ 4V). 6902f 5
W U TYPICAL PERFOR A CE CHARACTERISTICS Output Operating at 20MHz, Output Operating at 10MHz, VS = 5V VS = 3V
V+ = 5V, RSET = 10k, CL = 10pF V+ = 3V, RSET = 20k, CL = 10pF 1V/DIV 1V/DIV 0V 0V 12.5ns/DIV 69012 G06 25ns/DIV 69012 G07
U QUICK DESIG GUIDE
V+ RMOD 0.1µF RSET LTC6902 MHz 10 k 20 f = • Ω ; kHz 5 f 2 MHz OUT OUT 0 V+ SET N • M RSET ≤ ≤ DIV DIV MOD PH PH GND R Spreading Percentage SET = 20 • OUT1 OUT4 OUT4 RMOD OUT2 OUT3 OUT3 OUT2 OUT1 6902 F01
Figure 1. Typical Application with Design Equation Step 1. Select Multiphase Mode, Setting M DIVIDER SETTING FREQUENCY RANGE (fOUT • M)
By selecting the multiphase mode, a division parameter M N = 1 Connect DIV Pin to GND 2MHz to 20MHz is also chosen: N = 10 Leave DIV Open 200kHz to 2MHz N = 100 Connect DIV Pin to V+ < 200kHz 2-Phase: Connect PH Pin to GND M = 1 Note: The frequency range numbers are for a 5V supply where a 20MHz 3-Phase: Leave PH Open M = 3 output is the maximum frequency supported. For low supply applications 4-Phase: Connect PH Pin to V+ M = 4 (2.7V ≤ V+ ≤ 4V), the maximum rated output frequency is 10MHz and all of the above numbers should be halved.
Step 2. Choosing Programmable Divider Setting N
B. For constant frequency applications where frequency A. For applications using spread spectrum frequency accuracy is the primary specification: modulation (SSFM) or applications that are constant fre-
DIVIDER SETTING FREQUENCY RANGE (f
quency where low clock jitter is the primary specification:
OUT • M)
N = 1 Connect DIV Pin to GND > 500kHz* N = 10 Leave DIV Open 50kHz to 500kHz N = 100 Connect DIV Pin to V+ < 50kHz *The maximum frequency (fOUT • M) is 20MHz for 5V applications and is 10MHz for low supply applications (2.7V ≤ V+ ≤ 4V). 6902f 5
