8/22/2003 rev 1.0 linfinity division lxe1810 evaluation board warning read first 1. do not exceed the maximum output current rating of the eval board. 2. the maximum output current is set by the maximu m output voltage limit divided by the resistance of the tec device. 3. use a dummy resistor load first (20 to 50 ohms), not the tec device, to set up the output voltage clamp. read the application document to find out which resistor valu e changes to set the maximum output voltage limit. it is up to the user to make the resistor value change to fix the output voltage limit for the tec device that you are using. 4. the purpose of the evaluation boar d is to show the power effici ency of using the lx1810 class d power amplifier to drive a tec device. the pur pose is not to provide an accurate temperature control solution. there are many solutions for c ontrolling the temperature setting and accuracy and it?s not possible to provide this information in a general way because each application is different. 5. the closed loop feedback compensation will need to change for each different tec device used. the parameters for each tec device change with th e size and capacity to heat and cool. it?s not possible to provide the feedback compensation solution in a gene ral way. either the engineer designing the control system will need to know how to do these calculations or they will have to hire an engineering consultant to do the control system design.
microsemi linfinity microelectronics division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 0.5, 2003-08-22 www. microsemi . com lxe1810-100 thermo electric cooler drive linfinity division description k ey f eatures ? 100 watt output. ? input voltage +12 to +15 volts max. ? output current is 10a maximum at 10v. ? assy # lxevb1810-100. ? thermister input is not polar ity sensitive for rt-1 and rt-2. ? if the set temperature is lo wer than the room temperature when power is applied; the ou tput drive will put a positive potential across the thermo electric cooler. ? adjust r44 for temperature setting. ? adjust r39 for maximum voltage output. ? maximum voltage output divided by tec device resistance is maximum current output. maximum current not to exceed 10a. ? air flow required on heatsink for continuous 100w operation. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com/ l2 c25 c27 c22 adjust temp clamp level r39 r4 c5 hs1 hs2 hs3 hs4 r1 r9 u1 q17 q13 q6 r2 tec - tec + r43 q5 r3 q16 tb2 r17 q14 r28 r41 c19 r31 l1 r14 c9 q11 r26 c1 r22 c18 c11 c7 r15 r12 r21 c16 tb3 vr1 r30 r23 r18 r24 r19 q9 q8 c6 q18 c3 q19 r8 r7 q1 r20 q3 r25 q7 q12 r6 q2 r11 c21 q10 r10 r29 tb1 q4 r42 r13 vr3 c23 c8 r40 u2 r44 c4 c2 l l x x e e 1 1 8 8 1 1 0 0 - - 1 1 0 0 0 0
microsemi linfinity microelectronics division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 0.5, 2003-08-22 www. microsemi . com lxe1810-100 thermo electric cooler drive linfinity division application note the lx1810 has an internal 5v reference at pin 1. this reference is used with the pot adjustment that is the temperature setting and with the thermister resister divider that is the temperature feedb ack. the value of r43 is set equal to the value of the ther mister at the temperature of operation, (20%). the values for r42, r41, r40, c8, & c2 are used to set the loop compensation for stable closed loop operation. this eval board has been compensated for a marlow industries inc. mi1012t-01, tec device. the value of r39 sets the peak output voltage limit of the power amplifier. the pot a llows the user to adjust the output voltage for the tec device resistance which sets the maximum output current. the lx1810 has an internal cycle by cycle current limit that is activated after a count of 9 cycles of over current. wh en activated the lx1810 goes into a hiccup mode until it has 2 cycles of normal current. this mode will prevent damage when the output has a short circuit. the inductors, l1 and l2 ar e designed for the continuous current rating required by the device being driven by the power amplifier. at the 300khz switching frequency an inductance value between 5h and 10h should be used. c22 and c23 provide an lc low pass filter. the tec devices have a slow rate of change of temperature with time, which means the loop bandwidth will probably be under 10hz. this means that the lc filters can be set in the range of 500hz. therefore, you can use the largest cap value with the voltage and package size required by your design. the lx1810 has its fet drivers buffered so that the eval board is capable of driving the highest power to-220 package mosfets. an example of these devices are the fairchild ndp6030pl p-channel mosfet, capable of 20 amps and the sup70n03-09bp n-channel mosfet, capable of 20 amps. with these devices and the proper inductors, and the correct amount of heat sink, the power amplifier is capable of 10 amps continuous at an output voltage of 10 volts. so, any output power design is feasible up to this maximum design with the proper selection of components. a a p p p p l l i i c c a a t t i i o o n n
microsemi linfinity microelectronics division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 0.5, 2003-08-22 www. microsemi . com lxe1810-100 thermo electric cooler drive linfinity division application c1 470f 16v r9 34.8k c11 1.0f 10v 5vref gnd n/c 2.5vref rpwm cpwm n/u n/u n/u sleep n/u n/u ea in ea out fb out fb in+ fb in- cn pgnd p- n- n+ p+ pvdd vdd cp isi n/u c4 1.0f c5 1.0f r3 49.9k c7 100pf r2 34.8k r43 4.99k 301-021-1000 + - u2b lmc6482 r42 1.0m + - u2a lmc6482 c9 0.1f r44 20k c8 1.0f r41 100k c2 4.7f r40 10.0k r7 10.0k r8 10.0k r6 34.8k c6 1.0f 10v c3 10.0f 16v r1 0.010 2w 301-021- 1000 q3 ndp6030pl r33 20.0 q5 q 2 c25 100f 16v q1 r12 49.9 r13 10.0 q4 r15 10.0 r10 10.0 r11 1k vr1 pmt4104 r14 1k c16 0.1f q8 sup70n03-09bp r34 6.8 q7 q6 r18 10.0 r19 249 q9 r20 10.0 q10 r17 10.0 c18 0.1f q13 ndp6030pl r36 20.0 q15 q12 c27 100f 16v q11 r23 49.9 r24 10.0 q14 r26 10.0 r21 10.0 r22 1k vr3 1pmt4104 r25 1k c19 0.1f q18 sup70n03-09bp r37 6.8 q17 q16 r29 10.0 r30 249 q19 r31 10.0 q20 r28 10.0 c21 0.1f l2 6.6h c22 470f 16v c23 470f 16v 301-021-1000 l1 6.6h +15 vin +15 rtn rt-2 rt-1 out+ out - lx1810 part # nds0605 (q1, q2, q11, q12) part # bss138 (q4, q5, q14, q15) r39 100k r4 1k + + a a p p p p l l i i c c a a t t i i o o n n
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