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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
General Description
The DS1090 is a low-cost, dithered oscillator intended to be used as an external clock for switched-mode power supplies and other low-frequency applications. The dithering or sweeping function reduces peak-radiated emissions from the power supply at its fundamental frequency, as well as harmonic frequencies. The device consists of a resistor-programmed master oscillator, factory-programmed clock prescaler, and a pin-programmed dither circuit. These features allow the DS1090 to be used in applications where a spread-spectrum clock is desired to reduce radiated emissions. A combination of factory-set prescalers and external resistor allows for output frequencies ranging from 125kHz to 8MHz. Both dither frequency and dither percentage are set using control pins.
Applications
●● Switched-Mode Power Supplies ●● Servers ●● Printers ●● Embedded Microcontrollers ●● Industrial Controls
Typical Operating Circuit
VIN
45kΩ TO 91kΩ
VCC
VCC OUT
JC0
DS1090 JC1
RSET
J0
J1 GND
DC-DC STEP-DOWN CONVERTER
VOUT
EconOscillator is a trademark of Maxim Integrated Products, Inc.
Features
●● Low-Cost, Spread-Spectrum EconOscillator™ ●● Simple User Programming ●● O utput Frequency Programmable from 125kHz to 8MHz ●● Dither Percentage Programmable from 0% to 8% ●● Dither Rate Programmable (fMOSC/512, 1024, 2048,
or 4096) ●● 3.0V to 5.5V Single-Supply Operation ●● CMOS/TTL-Compatible Output ●● Operating Temperature Range: -40°C to +85°C
Ordering Information
PART
OUTPUT FREQUENCY
RANGE
DS1090U-1+ DS1090U-2+ DS1090U-4+
4MHz to 8MHz 2MHz to 4MHz 1MHz to 2MHz
DS1090U-8+
500kHz to 1MHz
DS1090U-16+
250kHz to 500kHz
DS1090U-32+
125kHz to 250kHz
Add “T” for Tape & Reel orders.
PRESCALER
1 2 4 8
16
32
PINPACKAGE
8 µSOP 8 µSOP 8 µSOP 8 µSOP
8 µSOP
8 µSOP
Pin Configuration
TOP VIEW
OUT 1 RSET 2 VCC 3 GND 4
DS1090 µSOP
8 JC1 7 JC0 6 J1 5 J0
19-7500; Rev 3; 9/16
DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Absolute Maximum Ratings
Voltage Range on VCC Relative to Ground..........-0.5V to +6.0V Voltage Range on Input Pins Relative to Ground............................... -0.5V to (VCC + 0.5V), not to exceed 6.0V
Operating Temperature Range............................ -40°C to +85°C Storage Temperature Range............................. -55°C to +125°C Soldering Temperature.......................................See IPC/JEDEC J-STD-020A Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Recommended DC Operating Conditions
(TA = -40°C to +85°C)
PARAMETER Supply Voltage
SYMBOL VCC (Note 1)
CONDITIONS
Input Logic 1 (J0, J1, JC0, JC1)
VIH
Input Logic 0 (J0, J1, JC0, JC1)
VIL
MIN 3.0 0.7 x VCC
-0.3
TYP
MAX 5.5
VCC + 0.3
+0.3 x VCC
UNITS V V
V
DC Electrical Characteristics
(VCC = +3.0V to +5.5V, TA = -40°C to +85°C, unless otherwise noted.)
PARAMETER Supply Current
High-Level Output Voltage (OUT) Low-Level Output Voltage (OUT)
SYMBOL ICC
VOH VOL
CONDITIONS CL = 15pF, VCC = 3.3V, RSET = 40kΩ CL = 15pF, VCC = 5.5V, RSET = 40kΩ IOH = -4mA VCC = min IOL = 4mA
High-Level Input Current (J0, J1, JC0, JC1)
IIH VIH = VCC
Low-Level Input Current (J0, J1, JC0, JC1) Resistor Current
IIL IRES
VIL = 0V VCC = max
MIN TYP MAX UNITS
1.4 1.7 3
mA
2.4 V
0.4 V
+1.0
µA
-1.0 µA 150 µA
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
AC Electrical Characteristics
(VCC = +3.0V to +5.5V, TA = -40°C to +85°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Internal Master Oscillator Frequency
fMOSC
Output Frequency Tolerance Voltage Frequency Variation Temperature Frequency Variation
∆fOUT ∆fOUT ∆fOUT
VCC = 3.3V, TA = +25°C
TA = +25°C, RSET = 60kΩ, VCC = 3.0V to 3.6V (Notes 2, 3)
TA = +25°C, RSET = 60kΩ, VCC = 4.5V to 5.5V (Notes 2, 3)
VCC = 3.3V (Notes 2, 3, 4)
Peak-to-Peak Dither (3σ) (Note 5)
Power-Up Time Load Capacitance Output Duty Cycle Output Rise/Fall Time
tPOR + tSTAB
CL
tR, tF
J0 = GND, J1 = GND J0 = VCC, J1 = GND J0 = GND, J1 = VCC J0 = VCC, J1 = VCC
(Note 6)
(Note 7) 4MHz to 8MHz, TA = +25°C (Note 3) <4MHz (Note 4) CL = 15pF
MIN TYP MAX UNITS 4.0 8.0 MHz
-3.0
+3.0
%
-0.5 -1.25
+0.5 +1.25
%
-2.0
+2.0
%
0 2% 4 8
0.1 0.5
ms
30 pF
45 55 50
%
20 ns
Note 1: All voltages referenced to ground. Note 2: This is the change observed in output frequency due to changes in temperature or voltage. Note 3: See the Typical Operating Characteristics section. Note 4: Parameter is g.