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19-3962; Rev 0; 6/04
MAX8720 Evaluation Kit
General Description
The MAX8720 evaluation kit (EV kit) demonstrates the high-power, dynamically adjustable notebook CPU applications circuit. This DC-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage CPU core VCC rail. The MAX8720 EV kit provides a digitally adjustable 0.275V to 1.85V output voltage from a 7V to 24V battery input range. It delivers up to 15A output current. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response. The MAX8720 has independent four-level logic inputs for setting the suspend voltage (S0-S1). Precision slewrate control provides just-in-time arrival at the new DAC setting, minimizing surge currents to and from the battery. This EV kit is a fully assembled and tested circuit board.
Features
High Speed, Accuracy, and Efficiency Fast-Response Quick-PWMTM Architecture 7V to 24V Input Voltage Range 0.275V to 1.85V Output Voltage Adjust Range (6-Bit DAC) 15A Load-Current Capability Precision-Adjustable Output Slew Control Remote Feedback and Ground Sense 300kHz Switching Frequency No Current-Sense Resistor PGOOD Blanking During Transition Overvoltage/Undervoltage Protection 28-Pin QSOP Package Low-Profile Components Fully Assembled and Tested
Evaluates: MAX8720
Ordering Information
PART MAX8720EVKIT TEMP RANGE 0C to +70C IC PACKAGE 28 QSOP
Component List
DESIGNATION QTY DESCRIPTION 10F 20%, 25V X5R ceramic capacitors (1210) TDK C3225X7R1E106M AVX 12103D106M Taiyo Yuden TMK325BJ106MM Not installed, 1000F, 50V aluminum electrolytic capacitor (12.5mm x 25mm) Sanyo 50MV1000AX 1000pF 10%, 50V C0G ceramic capacitors (0603) TDK 1608X7R1H102K or Murata GRM188R71H102K or Equivalent 470F, 2.5V, 9m low-ESR polymer capacitors (D case) Sanyo 2R5TPE470M9 DESIGNATION QTY DESCRIPTION 10F 20%, 6.3V X5R ceramic capacitor (0805) TDK C2012X5R0J106M or Taiyo Yuden AMK212BJ106MG 0.1F 10%, 25V X7R ceramic capacitor (0603) Murata GRM188R71E104K or TDK C1608X7R1E104K 1F 20%, 10V X5R ceramic capacitors (0805) Taiyo Yuden LMK212BJ105KG or TDK C2012X5R1A105M 0.22F 10%, 25V X5R ceramic capacitor (0805) Murata GRM219R71E224K Taiyo Yuden EMK212BJ224KG TDK C2012X7R1H224K
C1, C2
2
C8
1
C3
0
C9
1
C11, C15
2
C4, C10, C18
3
C5, C6, C7
3
C12
1
Quick-PWM is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX8720 Evaluation Kit Evaluates: MAX8720
Component List (continued)
DESIGNATION QTY DESCRIPTION 4700pF 10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H472K or equivalent 47pF 5%, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H470J or equivalent 3A, 30V Schottky diode Nihon EC31QS03L 100mA Schottky diode Central Semiconductor CMPSH-3 4-pin headers 3-pin headers 2-pin headers 0.8H, 20A, 4.9m power inductor Sumida CDEP104-0R8MC-50 (10mm x 10mm x 4.5mmm) DESIGNATION QTY DESCRIPTION n-channel MOSFET (SO-8) International Rectifier IRF7821 or Vishay/Siliconix Si7390DP (PowerPAK) n-channel MOSFETs (SO-8) International Rectifier IRF7832 or Vishay/Siliconix Si7356DP (PowerPAK) 10 5% resistor (0603) 100 5% resistors (0603) 100k 5% resistors (0603) Not installed (0603) Not installed (short PC trace) (0603) 100k 1% resistors (0603) 32.4k 1% resistor (0603) MAX8720EEI (28-pin QSOP) Rubber bumpers Shunts MAX8720 PC board
C13
1
N1
1
N2, N3 R1 R2, R3, R11 R4, R22-R27 R5, R6, R8 R7 R14, R18 R19 U1 None None None
2 1 3 7 0 0 2 1 1 4 11 1
C14
1
D1 D2 JU1, JU2, JU3 JU4, JU5, JU6 JUA0-JUA5 L1
1 1 3 3 6 1
Component Suppliers
SUPPLIER Central Semiconductor International Rectifier Murata Nihon Panasonic Sanyo Sumida Taiyo Yuden TDK TOKO PHONE 516-435-1110 310-322-3331 770-436-1300 847-843-7500 714-373-7939 619-661-6835 708-956-0666 800-348-2496 847-390-4373 408-432-8281 FAX 516-435-1824 310-322-3332 770-436-3636 847-843-2798 714-373-7183 619-661-1055 708-956-0702 847-925-0899 847-390-4428 408-943-9790 WEBSITE www.centralsemi.com www.irf.com www.murata.com www.niec.co.jp www.panasonic.com www.sanyovideo.com www.sumida.com www.t-yuden.com www.component.tdk.com www.tokoam.com www.vishay.com/mosfets
Vishay/Siliconix 408-970-5627 408-567-8942 Note: Indicate that you are using the MAX8720 when contacting these manufacturers.
2
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MAX8720 Evaluation Kit
Recommended Equipment
* 7V to 24V power supply, battery, or notebook AC adapter * * * * DC bias power supply, 5V at 100mA Dummy load capable of sinking 15A Digital multimeter (DMM) 100MHz dual-trace oscilloscope
Setting the Output Voltage
The MAX8720 uses a multiplexer that selects from two different inputs--the VID DAC inputs or the suspendmode S0-S1 inputs (JU1, JU2). On startup, the MAX8720 slews the target voltage from ground to either the decoded D0-D5 (SUS, JU4 = low) voltage or the S0-S1 voltage (SUS, JU4 = high). The output voltage can be digitally set from 0.275V to 1.85V (Table 1) from the D0-D5 pins (JUA0-JUA5) and from 0.275V to 0.650V (Table 2) from S0-S1 pins (JU1, JU2). There are three different ways of setting the output voltage: 1) Drive the external VID0-VID5 inputs (no jumpers installed). The output voltage can be set by driving the VID0-VID5 with open-drain drivers (pullup resistors are included on the board) or 3V/5V CMOS output logic levels (SUS, JU4 = low). 2) Install jumpers JUA0-JUA5. The output voltage can be set by installing jumpers JUA0-JUA5. When jumpers JUA0-JUA5 are not installed, D0-D5 inputs are at logic 1 (connected to VCC). When jumpers JUA0-JUA5 are installed, D0-D5 inputs are at logic 0 (connected to GND). The output voltage can be changed during operation by installing and removing jumpers JUA0-JUA5. When shipped, the EV kit is configured for operation with jumpers JUA0-JUA5 set for 1.30V output (Table 1). 3) Install jumpers JU1-JU2 (suspend mode, SUS = high). When shipped, the EV kit is configured for operation in the suspend mode with jumpers JU1 and JU2 set for 0.525V output (Table 2). In the suspend mode, the output voltage can be changed during operation by installing and removing jumpers JU1 and JU2. Refer to the MAX8720 data sheet for more information.
Evaluates: MAX8720
Quick Start
1) Ensure that the circuit is connected correctly to the supplies and dummy load prior to applying any power. 2) Verify that the shunts are across: * JUA0, JUA3, JUA5 * JU1 pins 1 and 3 (S0 = REF), JU2 pins 1 and 3 (S1 = REF), JU4 pins 2 and 3 (SUS = low) * JU5 pins 1 and 2 (SHDN high), JU6 pins 1 and 2 (SKIP high, forced PWM) 3) Turn on battery power prior to +5V bias power; otherwise, the output UVLO timer times out and the FAULT latch is set, disabling the regulator until +5V power is cycled or shutdown is toggled. 4) Verify that VOUT = 1.30V. Observe the output with the DMM and/or oscilloscope. Look at the LX switchingnode and MOSFET gate-drive signals while varying the load current.
Detailed Description
This 15A buck-regulator design is optimized for a 300kHz frequency and output voltage settings around 1.30V. The output voltage can be digitally set from 0.275V to 1.85V from the VID0-VID5 pins (Table 1). At VOUT = 1.30V and VIN = 12V, the inductor ripple is approximately 30% (LIR = 0.30).
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3
MAX8720 Evaluation Kit Evaluates: MAX8720
Jumper Settings Table 1. Jumper Functions: JUA0-JUA5 (Output Voltage Adjustment Settings)
D5 JUA5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D4 JUA4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D3 JUA3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 JUA2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 JUA1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 JUA0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 VOUT (V) 1.850 1.825 1.800 1.775 1.750 1.725 1.700 1.675 1.650 1.625 1.600 1.575 1.550 1.525 1.500 1.475 1.450 1.425 1.400 1.375 1.350 1.325 1.300 1.275 1.250 1.225 1.200 1.175 1.150 1.125 1.100 1.075 D5 JUA5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D4 JUA4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D3 JUA3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 JUA2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 JUA1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 JUA0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 VOUT (V) 1.050 1.025 1.000 0.975 0.950 0.925 0.900 0.875 0.850 0.825 0.800 0.775 0.750 0.725 0.700 0.675 0.650 0.625 0.600 0.575 0.550 0.525 0.500 0.475 0.450 0.425 0.400 0.375 0.350 0.325 0.300 0.275
4
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MAX8720 Evaluation Kit Evaluates: MAX8720
Table 2. Jumper Functions: JU1 and JU2 (Output Voltage Adjustment Settings, Suspend Mode)
SHUNT LOCATION JU2 1, 2 1, 2 1, 2 1, 2 1, 3 1, 3 1, 3 1, 3 Not installed Not installed Not installed Not installed 1, 4 1, 4 1, 4 1, 4 SHUNT LOCATION JU1 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 S1 PIN GND GND GND GND REF REF REF REF Open Open Open Open VCC VCC VCC VCC S0 PIN GND REF Open VCC GND REF Open VCC GND REF Open VCC GND REF Open VCC VOUT (V) 0.650 0.625 0.600 0.575 0.550 0.525 0.500 0.475 0.450 0.425 0.400 0.375 0.350 0.325 0.300 0.275
Table 3. Jumper Functions: JU3 (Switching-Frequency Selection)
JU3 1 and 2 1 and 3 1 and 4 Not installed (default) TON PIN Connected to GND. Connected to VCC. Connected to REF. Floating. FREQUENCY (kHz) 1000 200 550 300 (as shipped)
Note: Do not change the operating frequency without first recalculating component values. The frequency has a significant effect on preferred inductor value, peak current-limit level, MOSFET heating, PFM/PWM switchover point, output noise, efficiency, and other critical parameters.
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5
MAX8720 Evaluation Kit Evaluates: MAX8720
Table 4. Jumper Functions: JU4 (Suspend-Mode Control Input)
JU4 1 and 2 1 and 3 Not installed SUS PIN Connected to VCC. Connected to GND. SUS must be driven by an external signal connected to the DPRSLPVR pad. VOUT The suspend mode VID code, as programmed by S0 and S1, is delivered to the DAC. The suspend-mode multiplexer is not used. VOUT depends on the external DPRSLPVR level.
Table 5. Jumper Functions: JU5 (Shutdown Mode)
JU5 1 and 2 2 and 3 Not installed SHDN PIN Connected to VCC. Connected to GND. SHDN must be driven by an external signal connected to SHDN pad. MAX8720 OUTPUT Output enabled. Shutdown mode, VOUT = 0V. VOUT depends on the external SHDN level.
Table 6. Jumper Functions: JU6 (Pulse-Skipping Control Input)
JU6 1 and 2 SKIP PIN Connected to VCC. OPERATIONAL MODE Low-noise mode, forced-PWM operation. Normal operation, allows automatic PWM/PFM switchover for pulse-skipping at light-load, resulting in highest efficiency.
2 and 3
Connected to GND.
6
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7V TO 24V C11 1F 10V VCC R1 10 VDD 9 D5 7 N1 1 3 2 D4 D3 D2 D1 D0 DH LX U1 7 D1 6 CC DL 3 C13* 4700pF 1 2 2 1 3 N2 4 N3 C5 470F 2.5V C6 470F 2.5V 7 5 6 16 4 C7 470F 2.5V 8 5 6 8 C8 10F 6.3V 27 L1 0.8H VOUT 2 SHDN TIME 3 C14 47pF 26 D0 28 25 D1 24 D2 C9 0.1F 3 C15 1F 10V 1 23 D3 BST 4 +5V 22 D4 D2 CMPSH-3 21 D5 V+ VBIAS VCC VDD 1 R7 SHORT (PC TRACE) 26 5 6 8 17 C3 OPEN VDD C1 10F 25V C2 10F 25V
VBATT
GND
Figure 1. MAX8720 EV Kit Schematic
R14 100k 1%
VCC
SHDN
JU5
1
2
3
MAX8720
GND
REF C12 0.22F 10 TON VCC R8 OPEN ILIM FBS VCC R5 OPEN 7 S0 VCC VCC R4 100k 8 S1 VCC 1 20 SKIP GND 15 SUS 18 3 JU4 2 PGOOD 14 C10 1000pF GNDS 13 R3 100 REF 5 R2 100 VOUT_SENSE VID5 VCC R26 100k GND_SENSE VID4 VCC R25 100k PGOOD VID3 C18 1000pF R11 100 FB 4 VCC R27 100k
11 REF
VCC
JU3 4 3 1 2
VCC R24 100k D2 D5 VID2 JUA5 VCC R23 100k D1 D4 VID1 JUA4 VCC R22 100k D0 D3 VID0 JUA3 JUA0 JUA1 JUA2
R18 100k 1% 12
REF VCC JU1 3 4 1 2 JU2 3 4 1 2 VCC R19 32.4k 1% C4 1000pF R6 OPEN
REF
REF
JU6 1 2 3
DPRSLPVR
SKIP
Evaluates: MAX8720
_______________________________________________________________________________________
*NEEDED WITH IRF MOSFETS ONLY
MAX8720 Evaluation Kit
7
MAX8720 Evaluation Kit Evaluates: MAX8720
Figure 2. MAX8720 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX8720 EV Kit Component Placement Guide-- Solder Side
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MAX8720 Evaluation Kit Evaluates: MAX8720
Figure 4. MAX8720 EV Kit PC Board Layout--Component Side
Figure 5. MAX8720 EV Kit PC Board Layout--Internal GND/ Signal Layer
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9
MAX8720 Evaluation Kit Evaluates: MAX8720
Figure 6. MAX8720 EV Kit PC Board Layout--Internal GND Layer
Figure 7. MAX8720 EV Kit PC Board Layout--Solder Side
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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