1 ltc7541a improved industry standard cmos 12-bit multiplying dac n improved direct replacement for ad7541a and ad7541 n 4-quadrant multiplication n 12-bit end-point linearity: 0.5lsb dnl and inl over temperature n all grades guaranteed monotonic n maximum gain error: 1lsb n single 5v to 15v supply n ttl and cmos logic compatible n reduced sensitivity to op amp offset n low power consumption n virtually latch-up proof n low cost the ltc ? 7541a is a 12-bit resolution multiplying digital- to-analog converter (dac). laser-trimmed thin-film resistors provide excellent abso- lute accuracy. precision matched resistors and cmos circuitry result in remarkable stability with temperature and supply variations. the ltc7541a is a superior pin compatible replacement for the industry standard ad7541a/ad7541. improve- ments include better typical accuracy and stability and reduced sensitivity to output amplifier offset. the ltc7541a is also very resistant to latch-up. in addition to 2-quadrant and 4-quadrant multiplying configurations, the ltc7541a performs well in digitally programmable gain and noninverting voltage output ap- plications. low cost, improved performance and versatil- ity make the ltc7541a the best choice for many new designs and for upgrading existing systems. parts are available in 18-pin pdip and 18-pin so wide packages. features descriptio n u n motion control systems n microprocessor-controlled calibration n automatic test equipment n programmable gain amplifiers n digitally controlled filters applicatio n s u , ltc and lt are registered trademarks of linear technology corporation. typical applicatio n u 2-quadrant multiplying dac has less than 0.5lsb (typ) total unadjusted error digital input code 0 integral nonlinearity (lsb) 4095 7541a ta02 1024 2048 3072 1.0
0.5
0
0.5
1.0 512 1536 2560 3584 t a = 85 c t a = 25 c t a = 40 c integral nonlinearity over temperature v dd v ref ltc7541a r fb gnd 3 4 to 15 2 16 15v v in 17 18 1 out 1 33pf v out 7541 ta01 out 2 + 0.1 m f lt 1097 digital inputs
2 ltc7541a absolute m axi m u m ratings w ww u package/order i n for m atio n w u u electrical characteristics v dd = 15v, v ref = 10v, out 1 = out 2 = gnd = 0v, t a = t min to t max , unless otherwise specified. v dd to gnd ............................................... C 0.5v to 17v v ref to gnd.......................................................... 25v r fb to gnd ........................................................... 25v digital inputs to gnd .................. C 0.5v to (v dd + 0.5v) out 1, out 2 to gnd .................. C 0.5v to (v dd + 0.5v) power dissipation ............................................. 450mw (derate 6mw/ c above 75 c) maximum junction temperature ......... C 65 c to 125 c operating temperature range commercial (j, k versions).................. 0 c to 70 c industrial (b version) ...................... C 40 c to 85 c storage temperature range ................ C 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c ltc7541abn ltc7541absw ltc7541ajn ltc7541akn ltc7541ajsw ltc7541aksw order part number consult factory for military grade parts. t jmax = 150 c, q ja = 100 c/ w (n) t jmax = 150 c, q ja = 130 c/ w (sw) ltc7541ak/ltc7541ab 1
2
3
4
5
6
7
8
9
top view n package
18-lead pdip sw package
18-lead plastic so wide 18
17
16
15
14
13
12
11
10
out 1
out 2
gnd
bit 1 (msb)
bit 2
bit 3
bit 4
bit 5
bit 6
r fb
v ref
v dd
bit 12 (lsb)
bit 11
bit 10
bit 9
bit 8
bit 7 ltc7541aj symbol parameter conditions min typ max min typ max units accuracy resolution l 12 12 bits inl integral nonlinearity (note 1) l 1 0.5 lsb (relative accuracy) dnl differential nonlinearity guaranteed monotonic, t min to t max l 1 0.5 lsb ge gain error (note 2) t a = 25 c 6 1 lsb t min to t max l 8 2 lsb gain temperature coefficient (note 3) l 15 15ppm/ c i lkg output leakage current (note 4) t a = 25 c 5 5na t min to t max l 10 10 na psrr power supply rejection v dd = 15v 5% l 0.002 0.002 %/% reference input r ref v ref input resistance l 7 11 15 7 11 15 k w v ref input resistance C 100 C 100 ppm/ c temperature coefficient
3 ltc7541a v dd = 15v, v ref = 10v, out 1 = out 2 = gnd = 0v, t a = t min to t max , unless otherwise specified. the l denotes specifications which apply over the full operating temperature range. note 1: 0.5lsb = 0.012% of full scale. note 2: using internal feedback resistor. note 3: guaranteed by design, not subject to test. note 4: i out1 with all digital inputs = 0v or i out2 with all digital inputs = v dd . note 5: out 1 load = 100 w in parallel with 13pf. note 6: measured from digital input change to 90% of final analog value. digital inputs = 0v to v dd or v dd to 0v. note 7: v ref = 0v. all digital inputs 0v to v dd or v dd to 0v. measured using lt1363 as output amplifier. electrical characteristics block diagra m w 40k 10k 40k 20k 40k 20k 40k 20k 40k 40k 40k decoder bit 1
(msb) bit 2 gnd v dd v ref r fb bit 3 bit 4 bit 12
(lsb) out 1 out 2 7541 bd ttl/dtl/cmos compatible digital inputs ? ? ? information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. all grades symbol parameter conditions min typ max unit power supply v dd operating supply range l 51516 v i dd suppy current digital inputs = v ih or v il l 2ma digital inputs = 0v or v dd l 100 m a digital inputs v ih digital input high voltage l 2.4 v v il digital input low voltage l 0.8 v i in digital input current l 0.001 1 m a c in digital input capacitance (note 3), v in = 0v l 8pf ac performance propagation delay (notes 5, 6) 100 ns digital-to-analog glitch impulse (notes 5, 7) 1000 nv-sec multiplying feedthrough error v ref = 10v, 10khz sinewave 1.0 mv p-p output current settling time (note 5), to 0.01% for full-scale change 0.6 m s c out output capacitance (note 3) digital inputs = v ih c out1 l 200 pf c out2 l 70 pf digital inputs = v il c out1 l 70 pf c out2 l 200 pf
4 ltc7541a typical applicatio n s n u unipolar operation (2-quadrant multiplication) related parts bipolar operation (4-quadrant multiplication) v dd v ref ltc7541a r fb gnd 3 4 to 15 2 16 15v v ref
10 to 10v 17 18 1 out 1 33pf r1
10k v out 7541 ta04 out 2 + 0.1 m f 1/2 lt1112 + 1/2 lt1112 digital inputs table 2. bipolar offset binary code table digital input
v ref (2047/2048)
v ref (1/2048)
0v
? ref (1/2048)
? ref
msb lsb
1111 1111 1111
1000 0000 0001
1000 0000 0000
0111 1111 1111
0000 0000 0000 analog output
v out r2
20k r3
20k v dd v ref ltc7541a r fb gnd 3 4 to 15 2 16 15v v ref
10 to 10v 17 18 1 out 1 33pf v out 7541 ta03 out 2 + 0.1 m f lt1097 digital inputs table 1. unipolar binary code table digital input ? ref (4095/4096)
? ref (2048/4096) = v ref /2
? ref (1/4096)
0v
msb lsb
1111 1111 1111
1000 0000 0000
0000 0000 0001
0000 0000 0000 analog output
v out part number description comments ltc1257 complete serial i/o v out 12-bit dac 5v to 15v single supply in 8-pin so and pdip ltc1451/ltc1452/ltc1453 complete serial i/o v out 12-bit dacs 3v/5v single supply in 8-pin so and pdip ltc7543/ltc8143 serial i/o muliplying 12-bit dacs clear pin, serial data output (ltc8143) ltc8043 serial mulitplying 12-bit dac 8-pin so and pdip linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7487 (408) 432-1900 l fax : (408) 434-0507 l telex : 499-3977 lt/gp 1195 6k ? printed in usa ? linear technology corporation 1995
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