19-3474; Rev 0; 10/04 Silicon Oscillator with Low-Power Frequency Switching The MAX7377 dual-speed silicon oscillator with reset is a replacement for ceramic resonators, crystals, crystal oscillator modules, and discrete reset circuits. The device provides the primary and secondary clock source for microcontrollers in 3V, 3.3V, and 5V applications. The MAX7377 features a factory-programmed high-speed oscillator, a 32.768kHz oscillator, and a clock selector input. The clock output can be switched at any time between the high-speed clock and the 32.768kHz clock for low-power operation. Switchover is synchronized internally to provide glitch-free clock switching. Unlike typical crystal and ceramic resonator oscillator circuits, the MAX7377 is resistant to vibration and EMI. The high-output-drive current and absence of highimpedance nodes make the oscillator less susceptible to dirty or humid operating conditions. With a wide operating temperature range as standard, the MAX7377 is a good choice for demanding home appliance, industrial, and automotive environments. The MAX7377 is available in factory-programmed frequencies from 32.768kHz to 10MHz. See Table 1 for standard frequencies and contact the factory for custom frequencies. The MAX7377 is available in a 5-pin SOT23 package. Refer to the MAX7383 data sheet for frequencies ≥10MHz. The MAX7377 standard operating temperature range is -40°C to +125°C. See the Applications Information section for the extended operating temperature range. Features ♦ 2.7V to 5.5V Operation ♦ Accurate High-Speed 600kHz to 10MHz Oscillator ♦ Accurate Low-Speed 32kHz Oscillator ♦ Glitch-Free Switch Between High Speed and Low Speed at Any Time ♦ ±10mA Clock-Output Drive Capability ♦ 2% Initial Accuracy ♦ ±50ppm/°C Temperature Coefficient ♦ 50% Duty Cycle ♦ 5ns Output Rise and Fall Time ♦ Low Jitter: 160ps(P-P) at 8MHz (No PLL) ♦ 3mA Fast-Mode Operating Current (8MHz) ♦ 13µA Slow-Mode Operating Current (32kHz) ♦ -40°C to +125°C Temperature Range Ordering Information PART TEMP RANGE MAX7377AX_ _-T PIN-PACKAGE -40°C to +125°C 5 SOT23-5 The first two letters are AX. See Table 1 at the end of the data sheet for the two-letter code. Applications White Goods Handheld Products Automotive Portable Equipment Consumer Products Microcontroller Systems Appliances and Controls Pin Configuration TOP VIEW CLOCK 1 GND 2 E.C. 4 VCC MAX7377 SPEED 3 Typical Application Circuit appears at end of data sheet. 5 SOT23 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX7377 General Description MAX7377 Silicon Oscillator with Low-Power Frequency Switching ABSOLUTE MAXIMUM RATINGS VCC to GND .............................................................-0.3V to +6V All Other Pins to GND ................................-0.3V to (VCC + 0.3V) CLOCK Current ................................................................±10mA Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C) ...................571mW (U5 - 2) Operating Temperature Range .........................-40°C to +135°C Junction Temperature .....................................................+150°C Storage Temperature Range.............................-60°C to +150°C Lead Temperature (soldering, 10s).................................+300°C 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. ELECTRICAL CHARACTERISTICS (VCC = 2.7V to 5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Supply Voltage VCC Operating Supply Current ICC CONDITIONS MIN TYP 2.7 MAX UNITS 5.5 V fCLOCK = 8MHz, no load 3 5 mA fCLOCK = 32.768kHz, no load 13 25 µA LOGIC INPUT (SPEED) 0.7 x VCC Input High Voltage VIH V Input Low Voltage VIL 0.3 x VCC V Input Current IIN 2 µA CLOCK OUTPUT Output High Voltage Output Low Voltage Initial Fast CLOCK Frequency Accuracy 2 VCC = 4.5V, ISOURCE = 9mA VCC - 0.4 VCC = 2.7V, ISOURCE = 2.5mA VCC - 0.4 V VOH VOL fFCLOCK VCC = 4.5V, ISINK = 20mA 0.4 VCC = 2.7V, ISINK = 10mA 0.4 VCC = 5V, TA = +25°C (Note 2) -2 +2 VCC = 2.7V to 5.5V, TA = +25°C -4 +4 _______________________________________________________________________________________ V % Silicon Oscillator with Low-Power Frequency Switching (VCC = 2.7V to 5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL Fast CLOCK Frequency Temperature Sensitivity Initial Slow CLOCK Frequency Accuracy CONDITIONS MIN (Note 3) fSCLOCK Slow CLOCK Frequency Temperature Sensitivity VCC = 5V, TA = +25°C (Note 2) 32.440 VCC = 2.7V to 5.5V, TA = +25°C 31.785 (Note 3) CLOCK Output Duty Cycle 43 Observation of 8MHz output for 20s using a 500MHz oscilloscope CLOCK Output Jitter TYP MAX UNITS ±50 ±325 ppm/oC 32.768 33.096 33.751 kHz ±50 ±325 ppm/oC 50 57 % 160 psP-P CLOCK Output Rise Time tR 10% to 90% 5 ns CLOCK Output Fall Time tF 90% to 10% 5 ns Startup Delay VCC rising from 0 to 5V in 1µs Output Undervoltage Lockout UVLO Output Undervoltage Lockout Hysteresis VTHYS VCC rising 100 TA = +25°C 2.15 TA = -40°C to +125°C 2.05 2.2 µs 2.25 2.35 45 V mV Note 1: All parameters are tested at TA = +25°C. Specifications over temperature are guaranteed by design. Note 2: The frequency is determined by part number selection. See Table 1. Note 3: Guaranteed by design. Not production tested. _______________________________________________________________________________________ 3 MAX7377 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 5V, TA = +25°C, unless otherwise noted.) 53 49 51 50 49 50 49 48 48 47 47 47 46 46 46 45 45 -5 20 45 70 95 120 45 -55 -30 -5 70 95 4.3 120 CLOCK = 32kHz 13.5 SUPPLY CURRENT (µA) 53 52 51 50 49 48 1.5 13.0 1.4 12.5 12.0 11.5 46 10.5 45 10.0 4.9 5.2 5.5 0.9 0.8 -30 -5 20 45 70 95 -55 120 -30 -5 20 1.4 10 5 0 1.2 1.1 1.0 0.9 5.5 95 120 FREQUENCY vs. SUPPLY VOLTAGE 34.5 CLOCK = 32kHz 34.0 33.5 33.0 32.5 32.0 0.8 31.5 0.7 31.0 0.6 30.5 30.0 0.5 5.2 70 35.0 FREQUENCY (kHz) 15 CLOCK = 4MHz 1.3 SUPPLY CURRENT (mA) 20 45 TEMPERATURE (°C) SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.5 MAX7377 toc07 CLOCK = 32kHz 25 SUPPLY VOLTAGE (V) 1.0 0.5 -55 SUPPLY CURRENT vs. SUPPLY VOLTAGE 4.9 1.1 TEMPERATURE (°C) 30 4.6 1.2 0.6 SUPPLY VOLTAGE (V) 4.3 CLOCK = 4MHz 0.7 MAX7377 toc08 4.6 5.5 5.2 1.3 11.0 47 4.9 SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT (mA) CLOCK = 4MHz 4.3 4.6 SUPPLY VOLTAGE (V) 14.0 MAX7377 toc04 54 45 TEMPERATURE (°C) DUTY CYCLE vs. SUPPLY VOLTAGE 55 20 MAX7377 toc05 -30 TEMPERATURE (°C) DUTY CYCLE (%) 51 48 -55 4 52 MAX7377 toc06 50 53 MAX7377 toc09 51 52 CLOCK = 32kHz 54 DUTY CYCLE (%) 52 DUTY CYCLE (%) DUTY CYCLE (%) 53 CLOCK = 4MHz 54 55 MAX7377 toc02 MAX7377 toc01 CLOCK = 32kHz 54 DUTY CYCLE vs. SUPPLY VOLTAGE DUTY CYCLE vs. TEMPERATURE 55 MAX7377 toc03 DUTY CYCLE vs. TEMPERATURE 55 SUPPLY CURRENT (µA) MAX7377 Silicon Oscillator with Low-Power Frequency Switching 4.3 4.6 4.9 SUPPLY VOLTAGE (V) 5.2 5.5 4.3 4.6 4.9 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.2 5.5 Silicon Oscillator with Low-Power Frequency Switching CLOCK = 32kHz 32.8 4.04 FREQUENCY (kHz) FREQUENCY (MHz) 4.06 32.9 4.02 4.00 3.98 32.7 4.08 32.6 32.5 32.4 4.04 4.02 4.00 3.98 3.96 32.3 3.94 32.2 3.94 3.92 32.1 3.92 3.90 32.0 4.3 4.6 4.9 5.5 5.2 3.96 3.90 -55 SUPPLY VOLTAGE (V) CLOCK = 4MHz 4.06 FREQUENCY (MHz) CLOCK = 4MHz FREQUENCY vs. TEMPERATURE 4.10 MAX7377 toc11 MAX7377 toc10 4.08 FREQUENCY vs. TEMPERATURE 33.0 -30 -5 20 45 70 95 120 -55 -30 TEMPERATURE (°C) CLOCK OUTPUT WAVEFORM (CL = 10pF) 40ns/div 95 120 CLOCK f = 4MHz, CL = 100pF 40ns/div HIGH-SPEED TO LOW-SPEED TRANSITION (EXPANDED SCALE) MAX7377 toc16 20µs/div 70 MAX7377 toc15 40ns/div HIGH-SPEED TO LOW-SPEED TRANSITION 45 CLOCK f = 4MHz, CL = 50pF f = 4MHz, CL = 10pF 20 CLOCK OUTPUT WAVEFORM (CL = 100pF) MAX7377 toc14 CLOCK -5 TEMPERATURE (°C) CLOCK OUTPUT WAVEFORM (CL = 50pF) MAX7377 toc13 MAX7377 toc12 FREQUENCY vs. SUPPLY VOLTAGE 4.10 MAX7377 Typical Operating Characteristics (continued) (VCC = 5V, TA = +25°C, unless otherwise noted.) MAX7377 toc17 400ns/div _______________________________________________________________________________________ 5 MAX7377 Silicon Oscillator with Low-Power Frequency Switching Typical Operating Characteristics (continued) (VCC = 5V, TA = +25°C, unless otherwise noted.) LOW-SPEED TO HIGH-SPEED TRANSISTION (EXPANDED SCALE) LOW-SPEED TO HIGH-SPEED TRANSITION MAX7377 toc18 MAX7377 toc19 CLOCK SPEED 20µs/div 400ns/div Pin Description PIN NAME 1 CLOCK FUNCTION 2 GND 3 SPEED 4 VCC Positive Supply Voltage. Bypass VCC to GND with a 0.1µF capacitor. 5 E.C. Must be Externally Connected to VCC Push-Pull Clock Output Ground Clock-Speed Select Input. Drive SPEED low to select the 32kHz fixed frequency. Drive SPEED high to select factory-trimmed frequency. Detailed Description The MAX7377 is a dual-speed clock generator for microcontrollers (µCs) and UARTs in 3V, 3.3V, and 5V applications. (Figure 1). The MAX7377 is a replacement for two crystal oscillator modules, crystals, or ceramic resonators. The high-speed clock frequency is factory trimmed to specific values. A variety of popular standard frequencies are available. The low-speed clock frequency is fixed at 32.768kHz (Table 1). No external components are required for setting or adjusting the frequency. Supply Voltage The MAX7377 has been designed for use in systems with nominal supply voltages of 3V, 3.3V, or 5V and is specified for operation with supply voltages in the 2.7V to 5.5V range. See the Absolute Maximum Ratings section for limit values of power-supply and pin voltages. 6 Oscillator The clock output is a push-pull configuration and is capable of driving a ground-connected 500Ω or a positive-supply-connected 250Ω load to within 400mV of either supply rail. The clock output remains stable over the full operating voltage range and does not generate short output cycles when switching between high- and low-speed modes. A typical startup characteristic is shown in the Typical Operating Characteristics. Clock-Speed Select Input The MAX7377 uses a logic input pin, SPEED, to set clock speed. Take this pin low to select slow clock speed (nominally 32.768kHz) or high to select full clock speed. The SPEED input can be strapped to VCC or to GND to select fast or slow clock speed, or connected to a logic output (such as a processor port) used to change clock speed on the fly. If the SPEED input is connected to a processor port that powers up in the _______________________________________________________________________________________ Silicon Oscillator with Low-Power Frequency Switching MAX7377 600kHz TO 10MHz (HF OSCILLATOR) POR SPEED MUX LOGIC CLOCK The MAX7377’s jitter performance is given in the Electrical Characteristics table as a peak-to-peak value obtained by observing the output of the MAX7377 for 20s with a 500MHz oscilloscope. Jitter values are approximately proportional to the period of the output frequency of the device. Thus, a 4MHz part has approximately twice the jitter value of an 8MHz part. The jitter performance of clock sources degrades in the presence of mechanical and electrical interference. The MAX7377 is relatively immune to vibration, shock, and EMI influences, and thus provides a considerably more robust clock source than crystal or ceramic resonator-based oscillator circuits. Initial Power-Up and Operation 32kHz (LF OSCILLATOR) An internal power-up reset disables the oscillator until VCC has risen above 2.2V. The clock then starts up within 30µs (typ) at the frequency determined by the SPEED pin. Extended Temperature Operation Figure 1. Functional Diagram input condition, connect a pullup or pulldown resistor to the SPEED input to set the clock to the preferred speed on power-up. The leakage current through the resistor into the SPEED input is very low, so a resistor value as high as 500kΩ may be used. Applications Information Interfacing to a Microcontroller Clock Input The MAX7377 clock output is a push-pull, CMOS, logic output that directly drives any microprocessor (µP) or µC clock input. There are no impedance-matching issues when using the MAX7377. The MAX7377 is not sensitive to its position on the board and does not need to be placed right next to the µP. Refer to the microcontroller data sheet for clock-input compatibility with external clock signals. The MAX7377 requires no biasing components or load capacitance. When using the MAX7377 to retrofit a crystal oscillator, remove all biasing components from the oscillator input. The MAX7377 was tested to +135°C during product characterization and shown to function normally at this temperature (see the Typical Operating Characteristics). However, production test and qualification is only performed from -40°C to +125°C at this time. Contact the factory if operation outside this range is required. Power-Supply Considerations The MAX7377 operates with a 2.7V and 5.5V powersupply voltage. Good power-supply decoupling is needed to maintain the power-supply rejection performance of the MAX7377. Bypass VCC to GND with a 0.1µF surface-mount ceramic capacitor. Mount the bypass capacitor as close to the device as possible. If possible, mount the MAX7377 close to the microcontroller’s decoupling capacitor so that additional decoupling is not required. A larger value bypass capacitor is recommended if the MAX7377 is to operate with a large capacitive load. Use a bypass capacitor value of at least 1000 times that of the output load capacitance. _______________________________________________________________________________________ 7 MAX7377 Output Jitter VCC Silicon Oscillator with Low-Power Frequency Switching MAX7377 Typical Application Circuit Table 1. Standard Frequencies SUFFIX SUPPLY VOLTAGE VCC OSC1 CLOCK OSC2 E.C. µC MAX7377 STANDARD FREQUENCY (MHz) MG 1 OK 1.8432 QT 3.39545 QW 3.6864 RD 4 RH 4.1943 TP 8 For all other reset threshold options, contact factory. I/O PORT SPEED Table 2. Standard Part Numbers PIN-PACKAGE FREQUENCY (Hz) TOP MARK MAX7377AXMG 5 SOT23 1M AENE MAX7377AXOK 5 SOT23 1.8432M AEND MAX7377AXQT 5 SOT23 3.39545M AEMY MAX7377AXQW 5 SOT23 3.6864M AEMZ PART MAX7377AXRD 5 SOT23 4M AENA MAX7377AXRH 5 SOT23 4.1943M AENB MAX7377AXTP 5 SOT23 8M AENC Chip Information TRANSISTOR COUNT: 2027 PROCESS: BiCMOS 8 _______________________________________________________________________________________ Silicon Oscillator with Low-Power Frequency Switching SOT-23 5L .EPS PACKAGE OUTLINE, SOT-23, 5L 21-0057 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX7377 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)