rev. b information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a cmos 8-bit buffered multiplying dac ad7524 one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 617/329-4700 fax: 617/326-8703 features microprocessor compatible (6800, 8085, z80, etc.) ttl/cmos compatible inputs on-chip data latches endpoint linearity low power consumption monotonicity guaranteed (full temperature range) latch free (no protection schottky required) applications microprocessor controlled gain circuits microprocessor controlled attenuator circuits microprocessor controlled function generation precision agc circuits bus structured instruments general description the ad7524 is a low cost, 8-bit monolithic cmos dac designed for direct interface to most microprocessors. basically an 8-bit dac with input latches, the ad7524s load cycle is similar to the write cycle of a random access memory. using an advanced thin-film on cmos fabrication process, the ad7524 provides accuracy to 1/8 lsb with a typi- cal power dissipation of less than 10 milliwatts. a newly improved design eliminates the protection schottky previously required and guarantees ttl compatibility when using a +5 v supply. loading speed has been increased for compatibility with most microprocessors. featuring operation from +5 v to +15 v, the ad7524 inter- faces directly to most microprocessor buses or output ports. excellent multiplying characteristics (2- or 4-quadrant) make the ad7524 an ideal choice for many microprocessor con- trolled gain setting and signal control applications. functional block diagram ordering guide temperature nonlinearity package model 1 range (v dd = +15 v) option 2 ad7524jn C40 c to +85 c 1/2 lsb n-16 ad7524kn C40 c to +85 c 1/4 lsb n-16 ad7524ln C40 c to +85 c 1/8 lsb n-16 ad7524jp C40 c to +85 c 1/2 lsb p-20a ad7524kp C40 c to +85 c 1/4 lsb p-20a ad7524lp C40 c to +85 c 1/8 lsb p-20a ad7524jr C40 c to +85 c 1/2 lsb r-16a ad7524aq C40 c to +85 c 1/2 lsb q-16 ad7524bq C40 c to +85 c 1/4 lsb q-16 ad7524cq C40 c to +85 c 1/8 lsb q-16 ad7524sq C55 c to +125 c 1/2 lsb q-16 ad7524tq C55 c to +125 c 1/4 lsb q-16 ad7524uq C55 c to +125 c 1/8 lsb q-16 ad7524se C55 c to +125 c 1/2 lsb e-20a ad7524te C55 c to +125 c 1/4 lsb e-20a ad7524ue C55 c to +125 c 1/8 lsb e-20a notes 1 to order mil-std-883, class b processed parts, add/883b to part number. contact your local sales office for military data sheet. for u.s. standard military drawing (smd) see desc drawing #5962-87700. 2 e = leadless ceramic chip carrier: n = plastic dip; p = plastic leaded chip carrier; q = cerdip; r = soic.
rev. b C2C ad7524Cspecifications limit, t a = +25 8 c limit, t min , t max 1 parameter v dd = +5 v v dd = +15 v v dd = 5 v v dd = +15 v units test conditions/comments static performance resolution 8 8 8 8 bits relative accuracy j, a, s versions 1/2 1/2 1/2 1/2 lsb max k, b, t versions 1/2 1/4 1/2 1/4 lsb max l, c, u versions 1/2 1/8 1/2 1/8 lsb max monotonicity guaranteed guaranteed guaranteed guaranteed gain error 2 2 1/2 1 1/4 3 1/2 1 1/2 lsb max average gain tc 3 40 10 40 10 ppm/ c gain tc measured from +25 c to t min or from +25 c to t max dc supply rejection, 3 d gain/ d v dd 0.08 0.02 0.16 0.04 % fsr/% max d v dd = 10% 0.002 0.001 0.01 0.005 % fsr/% typ output leakage current i out1 (pin 1) 50 50 400 200 na max db0Cdb7 = 0 v; wr , cs = 0 v; v ref = 10 v i out2 (pin 2) 50 50 400 200 na max db0Cdb7 = v dd ; wr , cs = 0 v; v ref = 10 v dynamic performance output current settling time 3 (to 1/2 lsb) 400 250 500 350 ns max out1 load = 100 w , c ext = 13 pf; wr , cs = 0 v; db0Cdb7 = 0 v to v dd to 0 v. ac feedthrough 3 at out1 0.25 0.25 0.5 0.5 % fsr max v ref = 10 v, 100 khz sine wave; db0Cdb7 = at out2 0.25 0.25 0.5 0.5 % fsr max 0 v; wr , cs = 0 v reference input r in (pin 15 to gnd) 4 5555 k w min 20 20 20 20 k w max analog outputs output capacitance 3 c out1 (pin 1) 120 120 120 120 pf max db0Cdb7 = v dd ; wr , cs = 0 v c out2 (pin 2) 30 30 30 30 pf max c out1 (pin 1) 30 30 30 30 pf max db0Cdb7 = 0 v; wr , cs = 0 v c out2 (pin 2) 120 120 120 120 pf max digital inputs input high voltage requirement v ih +2.4 +13.5 +2.4 +13.5 v min input low voltage requirement v il +0.8 +1.5 +0.5 +1.5 v max input current i in 1 1 10 10 m a max v in = 0 v or v dd input capacitance 3 db0Cdb7 5 5 5 5 pf max v in = 0 v wr , cs 20 20 20 20 pf max v in = 0 v switching characteristics chip select to write setup time 5 see timing diagram t cs t wr = t cs ad7524j, k, l, a, b, c 170 100 220 130 ns min ad7524s, t, u 170 100 240 150 ns min chip select to write hold time t ch all grades 0 0 0 0 ns min write pulse width t wr t cs 3 t wr , t ch 3 0 ad7524j, k, l, a, b, c 170 100 220 130 ns min ad7524s, t, u 170 100 240 150 ns min data setup time t ds ad7524j, k, l, a, b, c 135 60 170 80 ns min ad7524s, t, u 135 60 170 100 ns min data hold time t dh all grades 10 10 10 10 ns min power supply i dd 1 2 2 2 ma max all digital inputs v il or v ih 100 100 500 500 m a max all digital inputs 0 v or v dd notes 1 temperature ranges as follows: j, k, l versions: C40 c to +85 c a, b, c versions: C40 c to +85 c s, t, u versions: C55 c to +125 c 2 gain error is measured using internal feedback resistor. full-scale range (fsr) = v ref . 3 guaranteed not tested. 4 dac thin-film resistor temperature coefficient is approximately C300 ppm/ c. 5 ac parameter, sample tested @ +25 c to ensure conformance to specification. specifications subje ct to change without notice . (v ref = +10 v, v out1 = v out2 = 0 v, unless otherwise noted)
ad7524 rev. b C3C absolute maximum ratings* (t a = +25 c, unless otherwise noted) v dd to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . . C0.3 v, +17 v v rfb to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 v v ref to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 v digital input voltage to gnd . . . . . . . . C0.3 v to v dd +0.3 v out1, out2 to gnd . . . . . . . . . . . . . C0.3 v to v dd +0.3 v power dissipation (any package) to +75 c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 mw derates above 75 c by . . . . . . . . . . . . . . . . . . . . 6 mw/ c operating temperature commercial (j, k, l) . . . . . . . . . . . . . . . . . C40 c to +85 c industrial (a, b, c) . . . . . . . . . . . . . . . . . . C40 c to +85 c extended (s, t, u) . . . . . . . . . . . . . . . . . C55 c to +125 c storage temperature . . . . . . . . . . . . . . . . . . C65 c to +150 c lead temperature (soldering, 10 secs) . . . . . . . . . . . +300 c *stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. warning! esd sensitive device caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the ad7524 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. terminology relative accuracy: a measure of the deviation from a straight line through the end points of the dac transfer function. normally expressed as a percentage of full scale range. for the ad7524 dac, this holds true over the entire v ref range. resolution: value of the lsb. for example, a unipolar con- verter with n bits has a resolution of (2 Cn ) (v ref ). a bipolar con- verter of n bits has a resolution of [2 C(nC1) ] [v ref ]. resolution in no way implies linearity. gain error: gain error is a measure of the output error be- tween an ideal dac and the actual device output. it is measured with all 1s in the dac after offset error has been adjusted out and is expressed in lsbs. gain error is adjustable to zero with an external potentiometer. feedthrough error: error caused by capacitive cou- pling from v ref to output with all switches off. output capacitance: capacity from out1 and out2 terminals to ground. output leakage current: current which appears on out1 terminal with all digital inputs low or on out2 terminal when all inputs are high. this is an error current which contributes an offset voltage at the amplifier output. pin configurations dip, soic plcc lccc
ad7524 rev. b C4C write mode when cs and wr are both low, the ad7524 is in the write mode, and the ad7524 analog output responds to data activity at the db0Cdb7 data bus inputs. in this mode, the ad7524 acts like a nonlatched input d/a converter. hold mode when either cs or wr is high, the ad7524 is in the hold mode. the ad7524 analog output holds the value correspond- ing to the last digital input present at db0Cdb7 prior to wr or cs assuming the high state. mode selection table cs wr mode dac response l l write dac responds to data bus (db0Cdb7) inputs. h x hold data bus (db0Cdb7) is locked out: x h hold dac holds last data present when wr or cs assumed high state. l = low state, h = high state, x = don't care. write cycle timing diagram figure 3. supply current vs. logic level typical plots of supply current, i dd , versus logic input voltage, v in , for v dd = +5 v and v dd = +15 v are shown above. circuit description circuit information the ad7524, an 8-bit multiplying d/a converter, consists of a highly stable thin film r-2r ladder and eight n-channel current switches on a monolithic chip. most applications require the addition of only an output operational amplifier and a voltage or current reference. the simplified d/a circuit is shown in figure 1. an inverted r-2r ladder structure is usedthat is, the binarily weighted currents are switched between the out1 and out2 bus lines, thus maintaining a constant current in each ladder leg indepen- dent of the switch state. figure 1. functional diagram equivalent circuit analysis the equivalent circuit for all digital inputs low is shown in figures 2. in figure 2 with all digital inputs low, the refer- ence current is switched to out2. the current source i leakage is composed of surface and junction leakages to the substrate while the 1 256 current source represents a constant 1-bit cur- rent drain through the termination resistor on the r-2r ladder. the on capacitance of the output n-channel switches is 120 pf, as shown on the out2 terminal. the off switch capacitance is 30 pf, as shown on the out1 terminal. analysis of the circuit for all digital inputs high is similar to figure 2 however, the on switches are now on terminal out1, hence the 120 pf appears at that terminal. figure 2. ad7524 dac equivalent circuitall digital inputs low interface logic information mode selection ad7524 mode selection is controlled by the cs and wr inputs.
ad7524 rev. b C5C analog circuit connections figure 4. unipolar binary operation (2-quadrant multiplication) table i. unipolar binary code table digital input msb lsb analog output 1111 1111 Cv ref (255/256) 1000 0001 Cv ref (129/256) 1000 0000 Cv ref (128/256) = Cv ref /2 0111 1111 Cv ref (127/256) 0000 0001 Cv ref (1/256) 0000 0000 Cv ref (0/256) = 0 note: 1 lsb = (2 C8 )(v ref ) = 1/256 (v ref ) microprocessor interface figure 6. ad7524/8085a interface figure 5. bipolar (4-quadrant) operation table ii. bipolar (offset binary) code table digital input msb lsb analog output 1111 1111 +v ref (127/128) 1000 0001 +v ref (1/128 ) 1000 0000 0 0111 1111 Cv ref (1/128) 0000 0001 Cv ref (127/128) 0000 0000 Cv ref (128/128) note: 1 lsb = (2 C7 )(v ref ) = 1/128 (v ref ) figure 7. ad7524/mc6800 interface ad7524 ad7524
ad7524 rev. b C6C power generation figure 8.
ad7524 rev. b C7C outline dimensions dimensions shown in inches and (mm). 20-terminal ceramic leadless chip carrier (e-20a) 1 20 4 9 8 13 19 bottom view 14 3 18 0.028 (0.71) 0.022 (0.56) 45 typ 0.015 (0.38) min 0.055 (1.40) 0.045 (1.14) 0.050 (1.27) bsc 0.075 (1.91) ref 0.011 (0.28) 0.007 (0.18) r typ 0.095 (2.41) 0.075 (1.90) 0.100 (2.54) bsc 0.200 (5.08) bsc 0.150 (3.81) bsc 0.075 (1.91) ref 0.358 (9.09) 0.342 (8.69) sq 0.358 (9.09) max sq 0.100 (2.54) 0.064 (1.63) 0.088 (2.24) 0.054 (1.37) 16-lead plastic dip (narrow) (n-16) 16 18 9 0.840 (21.33) 0.745 (18.93) 0.280 (7.11) 0.240 (6.10) pin 1 seating plane 0.022 (0.558) 0.014 (0.356) 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) max 0.130 (3.30) min 0.070 (1.77) 0.045 (1.15) 0.100 (2.54) bsc 0.160 (4.06) 0.115 (2.93) 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93) 20-lead plastic leadless chip carrier (plcc) (p-20a) 3 pin 1 identifier 4 19 18 8 9 14 13 top view (pins down) 0.395 (10.02) 0.385 (9.78) sq 0.356 (9.04) 0.350 (8.89) sq 0.048 (1.21) 0.042 (1.07) 0.048 (1.21) 0.042 (1.07) 0.020 (0.50) r 0.050 (1.27) bsc 0.021 (0.53) 0.013 (0.33) 0.330 (8.38) 0.290 (7.37) 0.032 (0.81) 0.026 (0.66) 0.180 (4.57) 0.165 (4.19) 0.040 (1.01) 0.025 (0.64) 0.056 (1.42) 0.042 (1.07) 0.025 (0.63) 0.015 (0.38) 0.110 (2.79) 0.085 (2.16) 16-lead cerdip (q-16) 16 1 8 9 0.310 (7.87) 0.220 (5.59) pin 1 0.005 (0.13) min 0.080 (2.03) max seating plane 0.023 (0.58) 0.014 (0.36) 0.200 (5.08) max 0.840 (21.34) max 0.150 (3.81) min 0.070 (1.78) 0.030 (0.76) 0.200 (5.08) 0.125 (3.18) 0.100 (2.54) bsc 0.060 (1.52) 0.015 (0.38) 15 0 0.320 (8.13) 0.290 (7.37) 0.015 (0.38) 0.008 (0.20) 16-lead narrow-body (soic) (r-16a) 16 9 8 1 0.3937 (10.00) 0.3859 (9.80) 0.2550 (6.20) 0.2284 (5.80) 0.1574 (4.00) 0.1497 (5.80) pin 1 seating plane 0.0098 (0.25) 0.0040 (0.10) 0.0192 (0.49) 0.0138 (0.35) 0.0688 (1.75) 0.0532 (1.35) 0.0500 (1.27) bsc 0.0099 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 8 0 0.0196 (0.50) 0.0099 (0.25) x 45
c542eC5C11/86 printed in u.s.a. C8C
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