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general description the max8784 evaluation kit (ev kit) is a fully assembledand tested surface-mount pcb that provides the volt- ages and features required for active-matrix, thin-film transistor (tft) liquid-crystal display (lcd) panels in lcd monitors and lcd tvs. the ev kit contains a step- up switching regulator, a two-stage positive charge pump for the tft gate-on supply, a single-stage nega- tive charge pump for the tft gate-off supply, and three high-current op amps. two capacitor-control delays are available: one to control the initial startup of the step- up, and the other to control the delay between the neg- ative and positive charge pumps. also included is a logic-controlled, high-voltage switch for the positive- gate driver supply. a high-voltage stress (hvs) mode is provided to increase the step-up and the positive charge-pump output voltages for stress testing the dis- play panel during production. a capacitive dummy load is provided at the high-voltage switch output for ease of testing without a panel attached. the ev kit operates from a dc supply voltage of +4.5v to +5.5v, as configured. the step-up switching regula- tor is configured for a +14v output providing at least 700ma. the positive charge pump is configured for a +28v output providing at least 50ma. the negative charge pump is configured for a -9v output providing at least 50ma. the three high-current op amps are each configured for a +7v output that can source or sink 180ma. the high-voltage switch can be controlled by external logic. the ev kit? input voltage range can be lowered to +4v at slightly lower load currents. the max8784 step-up switching regulator operates at 1.2mhz, allowing the use of tiny surface-mount compo- nents. the max8784 thin qfn package (0.8mm max height), with low-profile external components, allows this circuit to be less than 3mm high. features ? +4.5v to +5.5v input-voltage range ? output voltages +14v output at 700ma (step-up switching regulator) +28v output at 50ma (positive charge pump) -9v output at 50ma (negative charge pump) three high-current op amps (?80ma) ? 1.2mhz switching frequency ? all output voltages are resistor adjustable ? logic-controlled, high-voltage switch ? high-voltage stress mode for the step-up andpositive charge-pump output voltages ? capacitor-controlled initial startup delay andpositive charge-pump delay ? low-profile surface-mount components ? fully assembled and tested evaluates: max8784 max8784 evaluation kit ________________________________________________________________ maxim integrated products 1 19-0787; rev 0; 3/07 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. ordering information part temp range ic package MAX8784EVKIT+ 0? to +70?* 40 thin qfn-ep** + denotes a lead-free and rohs-compliant ev kit. * this limited temperature range applies to the ev kit pcb only. the max8784 ic temperature range is -40? to +85?. ** ep = exposed paddle. component list designation qty description c1, c2 2 10? ?0%, 6.3v x5r ceramiccapacitors (0603) tdk c1608x5r0j106m c3, c4 2 10? ?0%, 16v x5r ceramiccapacitors (1206) tdk c3216x5r1c106m c5 1 1? ?0%, 6.3v x5r ceramiccapacitor (0402) tdk c1005x5r0j105k c6 0 not installed, capacitor (0402) c7 1 330pf ?0%, 50v x7rceramic capacitor (0402) murata grm155r71h331k downloaded from: http:///
evaluates: max8784 max8784 evaluation kit 2 _______________________________________________________________________________________ component suppliers component list (continued) designation qty description c8 1 0.01? ?0%, 10v x5rceramic capacitor (0402) tdk c1005x5r1a103k c9, c13, c14, c15 4 0.1? ?0%, 25v x5r ceramiccapacitors (0402) tdk c1005x5r1e104k c10 1 0.22? ?0%, 6.3v x5rceramic capacitor (0402) tdk c1005x5r0j224k c11, c16 2 1? ?0%, 50v x7r ceramiccapacitors (1206) tdk c3216x7r1h105k c12 1 0.1? ?0%, 50v x7r ceramiccapacitor (0603) tdk c1608x7r1h104k c17 1 1500pf ?0%, 50v x7rceramic capacitor (0603) tdk c1608x7r1h152k d1 1 3a, 30v s chottky d iod e ( m - fl at) toshi b a c m s02 (te 12l, q) d2 1 220ma, 100v dual diode(sot23) fairchild mmbd4148se supplier phone website fairchild semiconductor 888-522-5372 www.fairchildsemi.com murata mfg. co., ltd. 770-436-1300 www.murata.com sumida corp. 847-545-6700 www.sumida.com tdk corp. 847-803-6100 www.component.tdk.com toshiba america electronic components, inc. 949-455-2000 www.toshiba.com/taec designation qty description ju1, ju2, ju4, ju5 4 2-pin headers ju3 1 3-pin header l1 1 3?, 3a dc inductor sumida cdrh6d28-3r0 r1 1 205k ?% resistor (0603) r2, r4, r5 3 20k ?% resistors (0603) r3 1 432k ?% resistor (0603) r6 1 187k ?% resistor (0603) r7?12 6 10k ?% resistors (0603) r13, r17, r18 3 100k ?% resistors (0603) r14, r15 0 not installed, resistors?hort(pc trace) (0603) r16 1 100k ?% resistor (0402) r19 1 1k ?% resistor (0603) r20 0 not installed, resistor?hort(pc trace) (0402) r21 1 82k ?% resistor (0603) u1 1 max8784etl+ (40-pin thinqfn-ep, 5mm x 5mm x 0.8mm) ? pcb: max8784evaluation kit+ 5 shunts note: indicate that you are using the max8784 when contacting these component suppliers. downloaded from: http:///
quick start recommended equipment +4.5v to +5.5v, 5a dc power supply one voltmeter procedure the max8784 ev kit is fully assembled and tested.follow the steps below to verify board operation. caution: do not turn on the power supply until all connections are completed: 1) verify that a shunt is installed across jumper ju1 (ev kit on). 2) verify that no shunt is installed across jumper ju2 (vgon internally connected to drn). 3) verify that a shunt is installed across pins 1-2 of jumper ju3 (vgon discharges toward avdd). 4) verify that no shunt is installed across jumper ju4 (vgon is not connected to the capacitive dummyload c17). 5) verify that no shunt is installed across jumper ju5 (high-voltage stress mode off). 6) connect the positive terminal of the power supply to the vin pad on the ev kit. connect the negative ter-minal of the power supply to the pgnd pad next to the vin pad. 7) turn on the power supply and set the supply to +5v. 8) verify that the step-up switching regulator output (avdd) is +14v. 9) verify that the gate-on supply (pout) is +28v. 10) verify that the gate-off supply (vgoff) is -9v. 11) verify that the op-amp outputs (out1, out2, and out3) are +7v. detailed description the max8784 ev kit contains a step-up switching regu-lator, a positive charge pump, a negative charge pump, three high-current op amps, and a high-voltage switch matrix. the ev kit is configured to operate from a dc power supply between +4.5v to +5.5v that can pro- vide at least 5a. the ev kit? input-voltage range can be extended to +4v to +5.5v at slightly lower load cur- rents. the max8784 step-up regulator operates at a switching frequency of 1.2mhz. the step-up switching regulator (avdd) generates a +14v output and provides at least 700ma. the step-up switching regulator output voltage can be adjusted from +7v to +19v by replacing feedback resistors r1 and r2 (refer to the design procedure, step-up regulator, output voltage selection section in the max8784 data sheet). operation at significantly higheroutput voltages may reduce the available output cur- rent and may require changes in component values or component voltage rating. the step-up switching regulator? startup delay time is configured by replacing capacitor c9. refer to the power-up sequence section in the max8784 data sheet for additional details.the gate-on (pout) supply consists of a two-stage positive charge pump that generates +28v and pro- vides greater than 50ma. this output can be adjusted from approximately +avdd to nearly +3xavdd by replacing feedback resistors r3 and r4 (refer to the design procedure, charge-pump regulators, output voltage selection section in the max8784 data sheet). the positive charge-pump regulator? startup delaytime is configured by replacing capacitor c8. refer to the positive charge-pump regulators and power-up sequence sections in the max8784 data sheet for additional details.the vgoff supply consists of a negative charge pump that generates -9v and provides greater than 50ma. this output can be adjusted from approximately 0v to -avdd by replacing feedback resistors r5 and r6 (refer to the design procedure, charge-pump regulator, output voltage selection section in the max8784 data sheet).the max8784 provides three high-current op amps that can each source or sink 180ma. the outputs of the amplifiers are configured for +7v (avdd/2). the max8784 contains two high-voltage switches that operate in a complementary fashion. one of the switch- es provides a connection between the pout and gon pins. the other switch provides a connection between the gon and drn pins. the switches can be con- trolled by an external ttl logic signal connected to the ctl pad. when ctl is high, gon is connected to pout, charg- ing vgon to the voltage of the positive charge pump at the pout pad. when ctl is low, gon is connected to drn, allowing vgon to discharge toward avdd (through resistor r19 and jumper ju3), or toward pgnd (through resistor r19 and jumper ju3). the max8784 ev kit also features a capacitive dummy load of 1500pf (c17) at the vgon output pad that can be connected through jumper ju4 to simulate a panel load to test the switch matrix. evaluates: max8784 max8784 evaluation kit _______________________________________________________________________________________ 3 downloaded from: http:///
evaluates: max8784 the max8784 features a hvs mode that can increase theoutput voltages of the step-up switching regulator and the positive charge pump to stress test the display panel dur- ing production. the step-up switching-regulator? output is increased to +17v in hvs mode, set by resistor r21 (refer to the hvs mode section in the max8784 data sheet). the positive charge-pump output is set to +30v inhvs mode and is not adjustable. jumper selection shutdown mode (shdn) jumper ju1 controls the shutdown pin ( shdn ) of the max8784 ic. the shutdown pin can also be controlled byan external logic controller connected to the ev kit? shdn pad. remove the shunt from jumper ju1 before connecting an external controller to the shdn pad. see table 1 for shunt positions. high-voltage switch control (ctl) jumper ju2 configures the setting of the high-voltageswitch control pin (ctl) of the max8784 ic. the ctl pin can also be controlled by an external logic controller con- nected to the ev kit? ctl pad. remove the shunt from jumper ju2 before connecting an external controller to the ctl pad. see table 2 for shunt positions. vgon discharge path (drn) the max8784 ev kit features a method to configure thevgon discharge path using resistor r19 and jumper ju3. when ctl is low, gon connects to drn, allowing vgon to discharge through r19. r19 can be connect- ed to avdd or to pgnd using jumper ju3. table 3 lists the selectable ju3 jumper options. if vgon? desired lower level is greater than avdd, discharge vgon toward avdd to save power. vgon? discharge rate can be adjusted by selecting a different value for r19. max8784 evaluation kit 4 _______________________________________________________________________________________ table 1. ju1 jumper selection ( shdn ) shunt position shdn pin connected to ev kit function installed* vin enabled not installed gnd (through resistor r17) shutdown mode none (external logic controller connected to shdn pad) external logic controller shdn driven by external logiccontroller. shdn is active-low. * default position. table 2. ju2 jumper selection (ctl) shunt position ctl pin connected to high-voltage switch configuration installed vin gon pin connected to pout pingon pin disconnected from drn pin not installed* gnd (through resistor r18) gon pin connected to drn pingon pin disconnected from pout pin none (external logic controller connected to ctl pad) external logic controller ctl driven by external logic controllerctl high: gon pin connected to pout pin ctl low: gon pin connected to drn pin * default position. table 3. ju3 jumper selection (drn) shunt position drn pin connected to gon discharge toward 1-2* avdd (through resistor r19) avdd 2-3 pgnd (through resistor r19) pgnd * default position. downloaded from: http:///
dummy load for the high-voltage switch output (vgon) the max8784 ev kit features a capacitive dummy loadof 1500pf (c17) at the vgon output pad to simulate a panel load to test the switch matrix. when testing with an lcd panel, disconnect the dummy load. jumper ju4 connects and disconnects the dummy load. table 4 lists the selectable ju4 jumper options. high-voltage stress mode (hvs) the max8784 ev kit features an option to increase theoutput voltage of the step-up switching regulator and the positive charge pump, to stress test the display panel during production. since the op-amp inputs are derived from the step-up converter output (avdd), their output voltages increase when avdd increases. jumper ju5 selects the high-voltage-stress mode for the max8784. table 5 lists the selectable ju5 jumper options. output voltage selection step-up switching regulator output voltage (avdd) the max8784 ev kit? step-up switching-regulator out-put (avdd) is set to +14v by feedback resistors r1 and r2. to generate output voltages other than +14v (from +7v to +19v), select different voltage-divider resistors. operation at significantly higher output volt- ages may reduce the available output current and may require changes in component values or voltage rating for capacitors c3 and c4. refer to the design procedure, step-up regulator, output voltage selection section in the max8784 data sheet for instructions onselecting resistors r1 and r2. positive charge-pump output (pout) the positive charge-pump output (pout) is set to +28vby voltage-divider resistors r3 and r4. to set pout to other voltages (up to nearly +3xavdd, limited to +35v) select different voltage-divider resistors. refer to the design procedure, charge-pump regulator, output voltage selection section in the max8784 data sheet for instructions on selecting resistors r3 and r4. negative charge-pump output (vgoff) the negative charge-pump output (vgoff) is set to -9v by voltage-divider resistors r5 and r6. to set vgoff to other voltages (from 0v to nearly -avdd), select different voltage-divider resistors. refer to the design procedure, charge-pump regulator, output voltage selection section in the max8784 data sheet for instructions on selecting resistors r5 and r6. op-amp outputs (out1, out2, and out3) the op-amp outputs (out1, out2, and out3) are setto +7v by voltage-divider resistors r7?12. to set the outputs to other voltages (from 0v to avdd), select dif- ferent voltage-divider resistors. evaluates: max8784 max8784 evaluation kit _______________________________________________________________________________________ 5 table 4. ju4 jumper selection (dummy load) shunt position vgon ev kit function installed connected to c17 testing mode not installed* not connected to c17 normal operation * default position. table 5. ju5 jumper selection (hvs) shunt position hvs pin connected to operating mode installed vin high-voltage- stress mode not installed* gnd (through resistor r13) normal mode * default position. downloaded from: http:///
evaluates: max8784 max8784 evaluation kit 6 _______________________________________________________________________________________ max8784 u1 r20 short (pc trace) r13 100k r5 20k 1% 19 20 29 v cc 24 neg1 vin 4.5v-5.5v pgnd pos2 pos1 c10 0.22 f hvs out3 out2 3 n.c. n.c. n.c. n.c. 26 13 30 27 28 3433 32 37 38 35 36 16 25 1514 vin vin out1 c110 f 6.3v c210 f 6.3v l1 3 h d1 c310 f 16v c410 f 16v avdd avdd 14v, 700ma r1205k 1%r2 20k 1% r2182k c7330pf 100k c6open r16 c80.01 f c90.1 f ju1 shdn agnd r17 100k ju2 r18100k ctl r19 1k 1 2 ju3 3 vgon bgnd ju4 c171500pf pout 28v, 50ma bgnd c16 1 f 50v r3432k 1%r4 20k 1% lxlx pgnd pgnd fb comp rset gdel adel shdn ctl drn gon pout fbp c2p c2n c1p c1n sup bgnd 3 4 1 2 40 39 c15 c14 c13 0.1 f 0.1 f 0.1 f out1neg2 out2 pos3 out3hvs ref agnd agnd fbn drvn 18 c12 0.1 f d2 l r avdd c11 1 f 50v bgnd vgoff -9v, 50ma ref 21 23 31 22 17 r6 187k 1% ju5 vin r12 10k r11 10k r9 10k r10 10k r7 10k r8 10k avdd avdd 5 6 7 10 9 8 11 12 c5 1 f 6.3v r14 short (pc trace) r15 short (pc trace) vin avdd 12 agnd figure 1. max8784 ev kit schematic downloaded from: http:///
evaluates: max8784 max8784 evaluation kit _______________________________________________________________________________________ 7 figure 2. max8784 ev kit component placement guide?omponent side downloaded from: http:///
evaluates: max8784 max8784 evaluation kit 8 _______________________________________________________________________________________ figure 3. max8784 ev kit pcb layout?omponent side downloaded from: http:///
evaluates: max8784 max8784 evaluation kit _______________________________________________________________________________________ 9 figure 4. max8784 ev kit pcb layout?nd layer 2 downloaded from: http:///
evaluates: max8784 max8784 evaluation kit 10 ______________________________________________________________________________________ figure 5. max8784 ev kit pcb layout?ower layer 3 downloaded from: http:///
evaluates: max8784 max8784 evaluation kit 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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 11 2007 maxim integrated products is a registered trademark of maxim integrated products, inc. figure 6. max8784 ev kit pcb layout?older side downloaded from: http:///

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