general description the max7378 dual-speed silicon oscillator with reset, is a replacement for ceramic resonators, crystals, crystal- oscillator modules, and discrete reset circuits. the max7378 provides the primary and secondary clock source and reset function for microcontrollers in 3v, 3.3v, and 5v applications. the max7378 features a factory-programmed high-speed oscillator, a 32.768khz oscillator, a clock selector input, and a microprocessor ( p) power-on-reset (por) supervisor. 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 max7378 is resistant to vibration and emi. the high-output-drive current and absence of high- impedance nodes make the oscillator less susceptible to dirty or humid operating conditions. with a wide operating temperature range as standard, the max7378 is a good choice for demanding home appli- ance, industrial, and automotive environments. the max7378 is available in an 8-pin ?ax package. refer to the max7384 data sheet for frequencies 10mhz. the max7378 standard operating tempera- ture range is -40 c to +125 c. see the applications information section for the extended operating temper- ature range. applications white goods automotive consumer products appliances and controls handheld products portable equipment microcontroller (?) systems features ? 2.7v to 5.5v operation ? accurate high-speed oscillator: 600khz to 10mhz ? accurate low-speed 32khz oscillator ? glitch-free switch between high speed and low speed at any time ? reset output holds the c in reset for 100s after clock startup ? 10ma clock-output drive capability ? 2% initial accuracy ? 50ppm/ c temperature coefficient ? 50% 7% output duty cycle ? 5ns output rise and fall time ? low jitter: 160ps (peak-to-peak) at 8mhz ? 2.4ma fast-mode operating current (8mhz) ? 11a slow-mode operating current (32khz) ? -40 c to +125 c temperature range max7378 silicon oscillator with low-power frequency switching and reset output ________________________________________________________________ maxim integrated products 1 ordering information 19-3350; rev 0; 7/04 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. pin configuration appears at end of data sheet. max7378 clock v l osc1 osc2 c rst i/o port v cc supply voltage enable rst/rst speed t ypical application circuit ?ax is a registered trademark of maxim integrated products, inc. part temp range reset output pin- package max7378a _ _ _ -40 o c to +125 o c active high push-pull 8 ?ax max7378b _ _ _ -40 o c to +125 o c active low push-pull 8 ?ax max7378c _ _ _ -40 o c to +125 o c open drain 8 max standard version is shown in bold. the first letter after the part number designates the reset output option. insert the letter cor- responding to the desired reset threshold level from table 1 in the next position. insert the two-letter code from table 2 in the remaining two positions for the desired frequency range. see table 3 for standard part numbers.
max7378 silicon oscillator with low-power frequency switching and reset output 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = 2.7v to 5.5v, v l = v cc , t a = -40? to +125 c, unless otherwise noted. typical values are at v cc = 5v, t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc to gnd .............................................................-0.3v to +6v all other pins to gnd ................................-0.3v to (v cc + 0.3v) clock current ................................................................ 10ma continuous power dissipation (t a = +70 c) 8-pin ?ax (derate 4.5mw/ c above +70 c) .... 362mw (u8-1) 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 parameter symbol conditions min typ max units operating supply voltage v cc 2.7 5.5 v logic output supply voltage v l must be connected to v cc 2.7 5.5 v i cc + i l f clock = 8mhz, no load 2.4 5.5 ma operating supply current i cc + i l f clock = 32.768khz, no load 11 25 ? shutdown current i shdn enable = 0v; i cc + i l 3.0 7.5 ? logic input (speed, enable) input high voltage v ih 0.7 x v cc v input low voltage v il 0.3 x v cc v input current i in 2 a clock output v l = 4.5v, i source = 9ma v l - 0.4 output high voltage v oh v l = 2.7v, i source = 2.5ma v l - 0.4 v v l = 4.5v, i sink = 20ma 0.4 output low voltage v ol v l = 2.7v, i sink = 10ma 0.4 v v cc = 5v, t a = +25 c (note 2) -2 +2 initial fast clock frequency accuracy f fclock v cc = 2.7v to 5.5v, t a = +25? -4 +4 % fast clock frequency temperature sensitivity (note 3) 50 325 ppm/ o c v cc = 5v, t a = +25 c 32.440 32.768 33.096 initial slow clock frequency accuracy f sclock v cc = 2.7v to 5.5v, t a = +25? 31.785 33.751 khz slow clock frequency temperature sensitivity (note 3) 50 325 ppm/ o c
max7378 silicon oscillator with low-power frequency switching and reset output _______________________________________________________________________________________ 3 note 1: all parameters are tested at t a = +25?. specifications over temperature are guaranteed by design. note 2: the frequency is determined by part number selection. see the ordering information . note 3: guaranteed by design. not production tested. electrical characteristics (continued) (v cc = 2.7v to 5.5v, v l = v cc , t a = -40? to +125 c, unless otherwise noted. typical values are at v cc = 5v, t a = +25 c.) (note 1) parameter symbol conditions min typ max units clock output duty cycle 43 50 57 % clock output jitter observation of 8mhz output for 20s using a 500mhz oscilloscope 160 ps p-p clock output rise time t r 10% to 90% 5 ns clock output fall time t f 90% to 10% 5 ns rst/ rst output t a = +25? v th - 1.5% v th + 1.5% reset threshold v th+ v cc rising t a = -40? to +125? v th - 5% v th + 5% v reset hysteresis v thys v hyst = {(v th+ ) - ( v th- )}/(v th- ) x 100% 2.0 % por delay v cc rising from 0v to (v th +200mv) in 1? 100 ? v l = 4.5v, i source = 9ma v l - 0.4 output high voltage v oh v l = 2.7v, i source = 2.5ma v l - 0.4 v v l = 4.5v, i sink = 20ma 0.4 output low voltage v ol v l = 2.7v, i sink = 10ma 0.4 v
t ypical operating characteristics (v cc = v l = 5v, t a = +25?, unless otherwise noted.) max7378 silicon oscillator with low-power frequency switching and reset output 4 _______________________________________________________________________________________ duty cycle vs. temperature max7378 toc01 temperature ( c) duty cycle (%) 120 95 45 70 -5 20 -30 46 47 48 49 50 51 52 53 54 55 45 -55 clock = 32khz duty cycle vs. temperature max7378 toc02 temperature ( c) duty cycle (%) 20 -5 -30 46 47 48 49 50 51 52 53 54 55 45 -55 45 70 95 120 clock = 4mhz duty cycle vs. supply voltage max7378 toc03 supply voltage (v) duty cycle (%) 5.2 4.9 4.6 46 47 48 49 50 51 52 53 54 55 45 4.3 5.5 clock = 32khz duty cycle vs. supply voltage max7378 toc04 supply voltage (v) duty cycle (%) 5.2 4.9 4.6 46 47 48 49 50 51 52 53 54 55 45 4.3 5.5 clock = 4mhz supply current vs. temperature max7378 toc05 temperature ( c) supply current ( a) 120 95 45 70 -5 20 -30 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 -55 clock = 32khz supply current vs. temperature max7378 toc06 temperature ( c) supply current (ma) 120 95 45 70 -5 20 -30 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 0.5 -55 clock = 4 mhz supply current vs. supply voltage max7378 toc07 supply voltage (v) supply current ( a) 5.2 4.9 4.6 8 9 10 11 12 13 14 4.3 5.5 clock = 32khz supply current vs. supply voltage max7378 toc08 supply voltage (v) supply current (ma) 5.2 4.9 4.6 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 0.5 4.3 5.5 clock = 4mhz frequency vs. supply voltage max7378 toc09 supply voltage (v) frequency (khz) 5.2 4.9 4.6 30.5 31.0 31.5 32.0 32.5 33.0 33.5 34.0 34.5 35.0 30.0 4.3 5.5 clock = 32khz
max7378 silicon oscillator with low-power frequency switching and reset output _______________________________________________________________________________________ 5 frequency vs. supply voltage max7378 toc10 supply voltage (v) frequency (mhz) 5.2 4.9 4.6 3.92 3.94 3.96 3.98 4.00 4.02 4.04 4.06 4.08 4.10 3.90 4.3 5.5 clock = 4mhz frequency vs. temperature max7378 toc11 temperature ( c) frequency (khz) 120 95 45 70 -5 20 -30 32.1 32.2 32.3 32.4 32.5 32.6 32.7 32.8 32.9 33.0 32.0 -55 clock = 32khz frequency vs. temperature max7378 toc12 temperature ( c) frequency (mhz) 120 95 45 70 -5 20 -30 3.92 3.94 3.96 3.98 4.00 4.02 4.04 4.06 4.08 4.10 3.90 -55 clock = 4mhz clock output waveform (cl = 10pf) max7378 toc13 40ns/div f = 4mhz, cl = 10pf clock output waveform (cl = 50pf) max7378 toc14 40ns/div f = 4mhz, cl = 50pf clock output waveform (cl = 100pf) max7378 toc15 40ns/div f = 4mhz, cl = 100pf maximum transient duration vs. reset threshold max7378 toc16 reset threshold overdrive (mv) maximum transient duration ( s) 200 400 600 800 100 1000 10 01000 reset = 4.29v reset occurs above the curve high-speed to low-speed transition max7378 toc17 clock speed 20 s/div high-speed to low-speed transition (expanded scale) max7378 toc18 clock speed 400 s/div t ypical operating characteristics (continued) (v cc = v l = 5v, t a = +25?, unless otherwise noted.)
max7378 silicon oscillator with low-power frequency switching and reset output 6 _______________________________________________________________________________________ detailed description the max7378 is a dual-speed clock generator with integrated reset for microcontrollers and uarts in 3v, 3.3v, and 5v applications (figure 1). the max7378 is a replacement for two crystal-oscillator modules, crystals, or ceramic resonators and a system-reset ic. the high- speed clock frequency is factory trimmed to specific values. a variety of popular standard frequencies are available (table 2). the low-speed clock frequency is fixed at 32.768khz (figure 1). no external components are required for setting or adjusting the frequency. supply voltage the max7378 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 sec- tion for limit values of power-supply and pin voltages. oscillator the clock output is a push-pull configuration and is capable of driving a ground-connected 500 ? or a posi- tive-supply connected 250 ? 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 . pin description pin name function 1v cc positive supply voltage. bypass v cc to gnd with a 0.1? capacitor. 2v l output supply voltage. connect v l to v cc . bypass v l to gnd with a 0.1? capacitor. 3 speed clock speed-select input. drive speed low to select the 32khz fixed frequency. drive speed high to select factory-trimmed frequency. 4 rst reset output. see the rst reset output options section for more details. 5 clock push-pull clock output 6 gnd ground 7 enable active-high clock enable input. see the enable input section for more details. 8n . c. no connect. no internal connection. low-speed to high-speed transition max7378 toc19 clock speed 20 s/div low-speed to high-speed transition (expanded scale) max7378 toc20 clock speed 400 s/div t ypical operating characteristics (continued) (v cc = v l = 5v, t a = +25?, unless otherwise noted.)
max7378 silicon oscillator with low-power frequency switching and reset output _______________________________________________________________________________________ 7 enable input the max7378 has an active-high enable input that con- trols the clock and reset outputs. the clock output is driven high when disabled. the reset asserts when dis- abled (low for active-low reset, high for active-high reset). drive enable low to disable the clock output on the next rising edge. drive enable high to activate the clock output. clock-speed select input the max7378 uses 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 may be strapped to v cc 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 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 500k ? may be used. applications information interfacing to a microcontroller clock input the max7378 clock output is a push-pull, cmos logic output that directly drives any ? or ? clock input. there are no impedance-matching issues when using the max7378. the max7378 is not sensitive to its posi- tion on the board and does not need to be placed right next to the ?. connect the max7378 v l pin and ? (or other clock-input device) to the same supply voltage level. refer to the ? data sheet for clock-input compati- bility with external clock signals. the max7378 requires no biasing components or load capacitance. when using the max7378 to retrofit a crystal oscillator, remove all biasing components from the oscillator input. rst reset output options the max7378 is available with three reset output stage options: push-pull with active-low output, push-pull with active-high output, and open drain with active-low out- put. the rst output is asserted when the monitored input (v cc ) drops below the internal v th- threshold and remains asserted for 100 s after the monitored input exceeds the internal v th+ threshold. the open-drain rst output requires an external pullup resistor. output jitter the max7378? jitter performance is given in the electrical characteristics table as a peak-to-peak value obtained by observing the output of the max7378 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 max7378 is relatively immune to vibration, shock, and emi influences, and thus provides a considerably more robust clock source than crystal or ceramic res- onator-based oscillator circuits. initial power-up and operation an intial power-up reset holds the reset output active for 100? (typ). however, the clock starts up within 30? (typ) at the frequency determined by the speed pin. power-supply brownout the rst output is asserted whenever v cc drops below the specified threshold level. the action of v cc drop- ping below the reset threshold and then rising back above the threshold asserts rst and starts a normal rst/rst logic 600khz to 10mhz (hf oscillator) por mux clock speed enable v cc v l max7378 32khz (lf oscillator) figure 1. functional diagram
max7378 power-on reset cycle. the max7378 reset circuit fea- tures internal hysteresis that creates two trip points: one for rising supply voltage and one for falling supply volt- age. the standard threshold values (see table 1) are the trip points for rising supply voltage. the trip point for falling supply voltage is calculated by subtracting the hysteresis value from the rising supply trip point. the hysteresis prevents the reset output from oscillat- ing (chattering) when v cc is near the voltage threshold. the reset circuit is immune to short transient v cc drops (see maximum transient duration vs. reset threshold in the typical operating characteristics ). extended temperature operation the max7378 was tested to +135? during product characterization and shown to function normally at this temperature (see the typical operating characteris- tics ). however, production test and qualification is only performed from -40? to +125? at this time. contact the factory if operation outside this range is required. power-supply considerations the max7378 operates with a 2.7v and 5.5v power- supply voltage. there are two power-supply pins, v cc and v l . v cc provides the main power input to the device and v l supplies the clock and reset output cir- cuits. good power-supply decoupling is needed to maintain the power-supply rejection performance of the max7378. bypass both v cc and v l to gnd with a 0.1? surface-mount ceramic capacitor. mount the bypassing capacitors as close to the device as possi- ble. if possible, mount the max7378 close to the ?? decoupling capacitor so that additional decoupling is not required. a larger value bypass capacitor is recom- mended if the max7378 is to operate with a large capacitive load. use a bypass capacitor value of at least 1000 times that of the output load capacitance. note: v l must be equal to v cc . silicon oscillator with low-power frequency switching and reset output 8 _______________________________________________________________________________________ pin configuration top view 1 2 3 4 8 7 6 5 n.c. enable gnd clock rst speed v l v cc max7378 max suffix reset threshold (v) r 2.57 m 4.29 suffix standard frequency (mhz) mg 1 ok 1.8432 qt 3.39545 qw 3.6864 rd 4 rh 4.1943 tp 8 table 1. standard reset threshold levels table 2. standard frequencies for all other reset threshold options, contact the factory. for all other frequency options, contact the factory.
max7378 silicon oscillator with low-power frequency switching and reset output _______________________________________________________________________________________ 9 part pin-package reset output type r eset t h r esh o l d ( v) frequency (mhz) MAX7378CRMG 8 ?ax open drain 2.57 1 max7378crok 8 ?ax open drain 2.57 1.8432 max7378crqt 8 ?ax open drain 2.57 3.39545 max7378crqw 8 ?ax open drain 2.57 3.6864 max7378crrd 8 ?ax open drain 2.57 4 max7378crrh 8 ?ax open drain 2.57 4.1943 max7378crtp 8 ?ax open drain 2.57 8 max7378cmmg 8 ?ax open drain 4.29 1 max7378cmok 8 ?ax open drain 4.29 1.8432 max7378cmqt 8 ?ax open drain 4.29 3.39545 max7378cmqw 8 ?ax open drain 4.29 3.6864 max7378cmrd 8 ?ax open drain 4.29 4 max7378cmrh 8 ?ax open drain 4.29 4.1943 max7378cmtp 8 ?ax open drain 4.29 8 table 3. standard part numbers chip information transistor count: 2027 process: bicmos
max7378 silicon oscillator with low-power frequency switching and reset output maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2004 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) 8lumaxd.eps package outline, 8l umax/usop 1 1 21-0036 j rev. document control no. approval proprietary information title: max 0.043 0.006 0.014 0.120 0.120 0.198 0.026 0.007 0.037 0.0207 bsc 0.0256 bsc a2 a1 c e b a l front view side view e h 0.60.1 0.60.1 ? 0.500.1 1 top view d 8 a2 0.030 bottom view 1 6 s b l h e d e c 0 0.010 0.116 0.116 0.188 0.016 0.005 8 4x s inches - a1 a min 0.002 0.95 0.75 0.5250 bsc 0.25 0.36 2.95 3.05 2.95 3.05 4.78 0.41 0.65 bsc 5.03 0.66 6 0 0.13 0.18 max min millimeters - 1.10 0.05 0.15 dim
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