Datasheet LTC6902 (Analog Devices) - 7
| Hersteller | Analog Devices |
| Beschreibung | Multiphase Oscillator with Spread Spectrum Frequency Modulation |
| Seiten / Seite | 16 / 7 — PI FU CTIO S. MOD (Pin 9):. OUT1, OUT2, OUT3, OUT4 (Pins 4, 5, 6 and 7):. … |
| Dateiformat / Größe | PDF / 213 Kb |
| Dokumentensprache | Englisch |
PI FU CTIO S. MOD (Pin 9):. OUT1, OUT2, OUT3, OUT4 (Pins 4, 5, 6 and 7):. GND (Pin 8):. SET (Pin 10):. To disable
Modelllinie für dieses Datenblatt
Textversion des Dokuments
LTC6902
U U U PI FU CTIO S
or it should be surrounded by a ground shield to prevent
MOD (Pin 9):
Spread Spectrum Frequency Modulation excessive coupling from other PCB traces. Setting Resistor Input. The value of the resistor (RMOD) connected between Pin 9 and V+ determines the amount
OUT1, OUT2, OUT3, OUT4 (Pins 4, 5, 6 and 7):
Oscillator of frequency modulation. The output frequency is always Outputs. These pins can drive 5kΩ and/or 10pF loads. modulated down from the frequency set by the R Larger loads may cause inaccuracies due to supply bounce SET resis- tor. For best performance, use a precision metal film resis- at high frequencies. tor with a value between 10k and 2M and limit the
GND (Pin 8):
Ground. Should be tied to a ground plane for capacitance on this pin to less than 10pF. The voltage on best performance. this pin is not static. Limiting the capacitance on this pin
SET (Pin 10):
Frequency Setting Resistor Input. The value is important for the part to perform properly.
To disable
of the resistor (R
the modulation, connect this pin to GND
. Grounding the SET) connected between Pin 10 and V+ determines the oscillator frequency. The voltage on this MOD pin disables the modulation and shuts down the pin is held at approximately 1.13V below the V+ voltage. modulation circuitry to save power.
Leaving the pin open
For best performance, use a precision metal film resistor
to disable the modulation is not recommended
. While with a value between 10k and 2M and limit the capacitance leaving the pin open, RMOD ≈ ∞, gives the mathematical on this pin to less than 10pF. result of 0% modulation, the open pin is susceptible to external noise coupling that can effect frequency accuracy.
W BLOCK DIAGRA
2 3 V+ – V DIV PH SET = 1.1V ±25% V+ 1 + RSET I MULTIPHASE SET MASTER OSCILLATOR OUT1 CIRCUIT SET 4 10 – G = 1 I SELECTS BETWEEN MASTER OUT2 fMASTER = 10MHz • 20kΩ • PROGRAMMABLE (V+ – V MULTIPHASE 5 I SET) MOD I DIVIDER ÷N SET OPTIONS AND ÷M + OUT3 V (N = 1, 10 OR 100) 6 BIAS – 2-PHASE (M = 1) R OUT4 MOD I 3-PHASE (M = 3) SET IMASTER 7 4-PHASE (M = 4) MOD 9 VSET – IMOD REF + MULTIPLYING 9-BIT PRBS I 7 ÷3200 MOD DAC GENERATOR CURRENT MIRROR 8 GND 6902 BD 6902f 7
U U U PI FU CTIO S
or it should be surrounded by a ground shield to prevent
MOD (Pin 9):
Spread Spectrum Frequency Modulation excessive coupling from other PCB traces. Setting Resistor Input. The value of the resistor (RMOD) connected between Pin 9 and V+ determines the amount
OUT1, OUT2, OUT3, OUT4 (Pins 4, 5, 6 and 7):
Oscillator of frequency modulation. The output frequency is always Outputs. These pins can drive 5kΩ and/or 10pF loads. modulated down from the frequency set by the R Larger loads may cause inaccuracies due to supply bounce SET resis- tor. For best performance, use a precision metal film resis- at high frequencies. tor with a value between 10k and 2M and limit the
GND (Pin 8):
Ground. Should be tied to a ground plane for capacitance on this pin to less than 10pF. The voltage on best performance. this pin is not static. Limiting the capacitance on this pin
SET (Pin 10):
Frequency Setting Resistor Input. The value is important for the part to perform properly.
To disable
of the resistor (R
the modulation, connect this pin to GND
. Grounding the SET) connected between Pin 10 and V+ determines the oscillator frequency. The voltage on this MOD pin disables the modulation and shuts down the pin is held at approximately 1.13V below the V+ voltage. modulation circuitry to save power.
Leaving the pin open
For best performance, use a precision metal film resistor
to disable the modulation is not recommended
. While with a value between 10k and 2M and limit the capacitance leaving the pin open, RMOD ≈ ∞, gives the mathematical on this pin to less than 10pF. result of 0% modulation, the open pin is susceptible to external noise coupling that can effect frequency accuracy.
W BLOCK DIAGRA
2 3 V+ – V DIV PH SET = 1.1V ±25% V+ 1 + RSET I MULTIPHASE SET MASTER OSCILLATOR OUT1 CIRCUIT SET 4 10 – G = 1 I SELECTS BETWEEN MASTER OUT2 fMASTER = 10MHz • 20kΩ • PROGRAMMABLE (V+ – V MULTIPHASE 5 I SET) MOD I DIVIDER ÷N SET OPTIONS AND ÷M + OUT3 V (N = 1, 10 OR 100) 6 BIAS – 2-PHASE (M = 1) R OUT4 MOD I 3-PHASE (M = 3) SET IMASTER 7 4-PHASE (M = 4) MOD 9 VSET – IMOD REF + MULTIPLYING 9-BIT PRBS I 7 ÷3200 MOD DAC GENERATOR CURRENT MIRROR 8 GND 6902 BD 6902f 7