_______________general description in applications with microprocessors (?s) that have a reset input, the max7705 is functionally and socket compatible with the tl7705, but requires no external components. it provides power-supply glitch immunity and a guaranteed power-up reset delay, while typically consuming 1/27 th the power from a +5v supply. the max7705 monitors the power supply in ? and digital systems. the reset output is valid for v cc down to 1v. the device offers excellent circuit reliability and low cost by eliminating external components and adjustments. a system reset is provided during power-up, power- down, and brownout conditions. when v cc is below the reset threshold, reset is low and holds the ? in reset. reset will go high 280ms after v cc rises above the reset threshold. the max7705 is available in 8-pin dip and so packages. ________________________applications minimum component count, low-cost processor systems ____________________________features ? no external components ? low cost ? precise reset threshold ? 280ms power-on reset delay ? 8-pin dip and so packages ______________ordering information * contact factory for dice specifications. max7705 ? power-supply monitor with reset ________________________________________________________________ maxim integrated products 1 1 2 3 4 8 7 6 5 v cc n.c. n.c. reset gnd n.c. n.c. n.c. max7705 v cc reset gnd m p * * * * the max7705 eliminates three external
components required by the tl7705. __________________pin configuration 1 2 3 4 8 7 6 5 v cc n.c. n.c. reset gnd n.c. n.c . n.c. max7705 dip/so top view
__________typical operating circuit call toll free 1-800-998-8800 for free samples or literature. 19-0151; rev 0; 6/93 part temp. range pin-package max7705cpa 0? to +70? 8 plastic dip max7705csa 0? to +70? 8 so max7705c/d 0? to +70? dice* feature max7705 tl7705 no. of external components required 0 3 operating supply current 65? 1.8ma power-supply glitch immunity yes no guaranteed minimum reset delay yes no +5v +3v 35? 1.8ma max7705epa -40? to +85? 8 plastic dip max7705esa -40? to +85? 8 so
max7705 ? power-supply monitor with reset 2 _______________________________________________________________________________________ absolute maximum ratings terminal voltage (with respect to gnd) v cc ......................................................................-0.3v to 6.0v reset ....................................................-0.3v to (v cc + 0.3v) input current, v cc ..............................................................20ma output current, reset ......................................................20ma rate-of-rise, v cc ............................................................100v/? continuous power disipation (t a = +70?) plastic dip (derate 9.09mw/? above +70?) ............727mw so (derate 5.88mw/? above +70?) .........................471mw operating temperature ranges: max7705c_ _ .....................................................0? to +70? max7705e_ _ ..................................................-40? to +85? storage temperature range .............................-65? to +160? lead temperature (soldering, 10sec) .............................+300? electrical characteristics (v cc = full range, t a = t min to t max , unless otherwise noted.) stresses beyond those listed under ?bsolute 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. parameter conditions min typ max units max7705c 1.0 5.5 v cc range max7705e 1.2 5.5 v max7705c, v cc < 5.5v 65 150 supply current max7705e, v cc < 5.5v 65 200 ? reset threshold 4.50 4.65 4.75 v v cc to reset delay v cc = reset threshold max to reset threshold min 20 ? reset active timeout period v cc = reset threshold max, v cc rising 140 280 560 ms i sink = 3.2ma, v cc = reset threshold min 0.4 v i sink = 50?, v cc 3 1.0v, max7705c 0.3 reset output voltage i source = 800?, v cc 3 reset threshold max v cc - 1.5 i sink = 100?, v cc 3 1.2v, max7705e 0.4
max7705 ? power-supply monitor with reset _______________________________________________________________________________________ 3 24 0 -60 100 power-down reset delay
vs. temperature 4 20 temperature (?) power-down reset delay ( m s) 60 12 8 -20 20 16 v cc stepped from reset threshold
max to reset threshold min 300 0 -60 100 power-up reset delay
vs. temperature 50 250 temperature (?) power-up reset delay (ms) 60 150 100 -20 20 200 v cc = reset threshold max
v cc rising 100 20 -60 -20 60 100 supply current
vs. temperature 40 80 temperature (?) supply current ( m a) 20 60 0 note: steady-state supply
current is independent
of reset output status no load v cc = +5v v cc = +4v v cc = +3v v cc = +2v v cc = +1v 4.640 -60 -20 60 100 reset threshold
vs. temperature 4.650 temperature (?) reset threshold (v) 20 4.660 4.630 4.655 4.645 4.665 4.635 __________________________________________typical operating characteristics (t a = +25?, unless otherwise noted.) ______________________________________________________________pin description pin name function 1,2,3,6,7 n.c. no connection. there is no internal connection to these pins. 4 gnd ground 5 reset reset output remains low while v cc is below the reset threshold, and for 280ms after v cc rises above the reset threshold. 8 v cc +5v supply voltage
max7705 ? power-supply monitor with reset 4 _______________________________________________________________________________________ __________applications information replacing the tl7705 with a max7705 in an existing design the max7705 has only three active pins: v cc , gnd, and reset . when using a tl7705 with a ? that has a reset input, simply plug the max7705 into the same socket and omit the reset pull-up resistor, reset timing capacitor, and reference bypass capacitor (see the typical operating circuit ). the max7705 monitors the v cc voltage and asserts reset whenever v cc falls below the reset threshold. the reset power-up delay is created by an internal fixed oscillator. this delay is 100% tested and guaran- teed over the full temperature range. the reset out- put both sources and sinks current (see reset output voltage in the electrical characteristics ). negative-going v cc transients the max7705 asserts reset during power-up, power-down, and brownout conditions. however, it is relatively immune to short-duration negative-going v cc transients (glitches). figure 1 shows typical transient duration vs. reset com- parator overdrive for which the max7705 does not gen- erate a reset pulse. the graph was generated using a fast-edge, negative-going pulse applied to v cc , starting 1.5v above the actual reset threshold and ending below the reset threshold by the magnitude indicated (reset comparator overdrive). it indicates the typical maxi- mum pulse width a negative-going v cc transient may have without causing a reset pulse to be issued. as the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. typically, a v cc transient that goes 100mv below the reset threshold and lasts 40? or less will not cause a reset pulse to be issued. a 0.1? bypass capacitor mounted as close as possible to pin 2 (v cc ) provides additional transient immunity. ensuring a valid reset output down to v cc = 0v when v cc falls below 1v, the max7705 reset output no longer sinks current; it becomes high impedance. therefore, high-impedance cmos logic inputs con- nected to the reset output can drift to indeterminate voltages. in most applications this presents no prob- lem, as ? and other circuitry is generally inoperative with v cc below 1v. in applications where the reset output must be valid down to 0v, adding a pull-down resistor to the reset pin (as shown in figure 2) will cause any stray leakage currents to flow to ground, holding reset low. the resistance value of r1 is not critical. it should be about 100k , which is large enough not to load reset and small enough to pull reset to ground. 150 0 10 100 10k 50 100 reset comparator overdrive, v th - v cc (mv) maximum transient duration ( m s) 1k t a = +25? 10ns r1 v cc gnd max7705 reset figure 1. maximum transient duration without causing a reset pulse vs. reset comparator overdrive figure 2. reset valid to v cc = ground circuit
___________________chip topography transistor count = 380; substrate connected to v cc . max7705 ? power-supply monitor with reset _______________________________________________________________________________________ 5 4.7k v cc gnd reset max7705 reset v cc gnd m p buffer buffered reset
to other system
components figure 3. interfacing to ?s with bidirectional reset i/o interfacing to ?s with bidirectional reset inputs ?s with bidirectional reset pins, such as motorola? 68hc11 series, can contend with the max7705 reset output. if, for example, the max7705 reset output is asserted high and the ? wants to pull it low, an inde- terminate logic level may result. to correct this, con- nect a 4.7k resistor between the max7705 reset output and the ? reset i/o, as in figure 3. buffer the reset signal to other system components. reset v cc gnd 0.045"
(1.143mm) 0.056"
(1.422mm)
max7705 ? power-supply monitor with reset 6 _______________________________________________________________________________________ c a a2 e1 d e e a e b a3 b1 b dim
a
a1
a2
a3
b
b1
c
d
d1
e
e1
e
e a
e b
l
a min
? 0.015
0.125
0.055
0.016
0.050
0.008
0.348
0.005
0.300
0.240
? 0.115
0? max
0.200
? 0.175
0.080
0.022
0.065
0.012
0.390
0.035
0.325
0.280
0.400
0.150
15? min
? 0.38
3.18
1.40
0.41
1.27
0.20
8.84
0.13
7.62
6.10
? 2.92
0? max
5.08
? 4.45
2.03
0.56
1.65
0.30
9.91
0.89
8.26
7.11
10.16
3.81
15? inches millimeters 2.54 bsc 7.62 bsc 0.100 bsc 0.300 bsc a1 l d1 e 21-324a a 8-pin plastic
dual-in-line
package _______________________________________________________package information
max7705 ? power-supply monitor with reset _______________________________________________________________________________________ 7 l dim
a
a1
b
c
d
e
e
h
h
l
a min
0.053
0.004
0.014
0.007
0.189
0.150
0.228
0.010
0.016
0? max
0.069
0.010
0.019
0.010
0.197
0.157
0.244
0.020
0.050
8? min
1.35
0.10
0.35
0.19
4.80
3.80
5.80
0.25
0.40
0? max
1.75
0.25
0.49
0.25
5.00
4.00
6.20
0.50
1.27
8? inches millimeters a 8-pin plastic
small-outline
package h e d e a a1 c h x 45? 0.127mm
0.004in. b 1.27 bsc 0.050 bsc 21-325a __________________________________________ package information (continued)
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. 8 ___________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 (408) 737-7600 1993 maxim integrated products printed usa is a registered trademark of maxim integrated products. max7705 ? power-supply monitor with reset minimum nominal nominal reset watchdog power- reset pulse timeout backup- ce - fail manual- watch- low- active- battery- part threshold width period battery write com- reset dog line high on number (v) (ms) (sec) switch protect parator input output output reset output max690a/692a 4.65/4.40 140 1.6 44 max691a/693a 4.65/4.40 140/adj. 1.6/adj. 44 /10ns 44444 max696 adj. 35/adj. 1.6/adj. 4 4 44 44 max697 adj. 35/adj. 1.6/adj. 44 44 4 max700 4.65/adj. 200 - 44 max703/704 4.65/4.40 140 - 444 max705/706 4.65/4.40 140 1.6 444 max706p 2.63 140 1.6 444 4 max706r/s/t 2.63/2.93/ 140 1.6 444 3.08 max707/708 4.65/4.40 140 - 44 4 max708r/s/t 2.63/2.93/ 140 - 44 4 3.08 max709l/m/ 4.65/4.40/ 140 - r/s/t 2.63/2.93/3.08 max791 4.65 140 1 44 /10ns 4 444 44 max792l/m/ 4.65/4.40/ 140 1 4 /10ns 4 444 4 r/s/t 2.63/2.93/3.08 max800l/m 4.60/4.40 140 1.6/adj. 44 /10ns 4 / 2% 44 44 max802l/m 4.60/4.40 140 1.6 44 / 2% max805l 4.65 140 1.6 44 4 max813l 4.65 140 1.6 444 4 max820l/m/ 4.65/4.40/ 140 1 4 /10ns 4 / 2% 444 4 r/s/t 2.63/2.93/3.08 max1232 4.37/4.62 250 0.15/0.60/1.2 4 max1259 - - - 44 m p supervisory circuits
e nglish ? ???? ? ??? ? ??? what's ne w p roducts solutions de sign ap p note s sup p ort buy comp any me mbe rs max7705 part number table notes: see the max7705 quickview data sheet for further information on this product family or download the max7705 full data sheet (pdf, 70kb). 1. other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales . 2. didn't find what you need? ask our applications engineers. expert assistance in finding parts, usually within one business day. 3. part number suffixes: t or t&r = tape and reel; + = rohs/lead-free; # = rohs/lead-exempt. more: see full data sheet or part naming c onventions . 4. * some packages have variations, listed on the drawing. "pkgc ode/variation" tells which variation the product uses. 5. part number free sample buy direct package: type pins size drawing code/var * temp rohs/lead-free? materials analysis max7705epa+ -40c to +85c rohs/lead-free: yes max7705epa rohs/lead-free: no max7705c wa 0c to +70c rohs/lead-free: no MAX7705EWA -40c to +85c rohs/lead-free: no max7705c pa pdip;8 pin;.300" dwg: 21-0043d (pdf) use pkgcode/variation: p8-1 * 0c to +70c rohs/lead-free: no materials analysis max7705c pa+ pdip;8 pin;.300" dwg: 21-0043d (pdf) use pkgcode/variation: p8+1 * 0c to +70c rohs/lead-free: yes materials analysis didn't find what you need?
c ontac t us: send us an email c opyright 2 0 0 7 by m axim i ntegrated p roduc ts , dallas semic onduc tor ? legal n otic es ? p rivac y p olic y
|
