General Description
The MAX15000A evaluation kit (EV kit) is a fully assem-
bled and tested circuit board that contains a 9W fly-
back DC-DC converter. The circuit is configured for
+5V and +15V output voltages and provides up to 1.5A
and 100mA of current at each respective output. Power
for the circuit can be provided from either a +36V to
+72V or a -36V to -72V DC source.
High efficiency up to 81% is achieved using a flyback
DC-DC converter topology. The surface-mount trans-
former provides up to 1500V galvanic isolation for both
outputs. Low cost is achieved through the use of prima-
ry-side regulation while undervoltage lockout (UVLO)
and digital soft-start provide for a robust 9W isolated
power supply.
Operation at 350kHz allows the use of small magnetics
and output capacitors.
Warning: The MAX15000A EV kit is designed to oper-
ate with high voltages. Dangerous voltages are present
on this EV kit and on equipment connected to it. Users
who power up this EV kit or power the sources connect-
ed to it must be careful to follow safety procedures
appropriate to working with high-voltage electrical
equipment.
Under severe fault or failure conditions, this EV kit may
dissipate large amounts of power, which could result in
the mechanical ejection of a component or of compo-
nent debris at high velocity. Operate this kit with care to
avoid possible personal injury.
Features
♦+36V to +72V or -36V to -72V DC Input Range
♦Isolated Outputs
VOUT1: +5V Provides Up to 1.5A
VOUT2: +15V Provides Up to 100mA
♦±5% (typ) Load Regulation for the +5V Output
Set Point (150mA to 1.5A)
♦81% Efficiency at 48V Input and Full Load
♦Cycle-by-Cycle Current Limit
♦350kHz Switching Frequency
♦Digital Soft-Start
♦High-Accuracy Undervoltage Lockout (UVLO)
♦Undervoltage Lockout Open-Drain Flag Output
♦Designed for 1500V Isolation with Primary-Side
Regulation
♦Low-Cost Flyback Design
♦Fully Assembled and Tested
Evaluates: MAX15000A
MAX15000A Evaluation Kit
________________________________________________________________ Maxim Integrated Products 1
19-4012; Rev 0; 3/06
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.
Ordering Information
PART TEMP RANGE
IC PACKAGE
MAX15000AEVKIT
0°C to +70°C 10 µMAX®
Component List
DESIGNATION
QTY
DESCRIPTION
C1, C2 2
1µF ±10%, 100V X7R ceramic
capacitors (1812)
TDK C4532X7R2A105K
C3 1
68µF, 6.3V electrolytic capacitor (V)
Kemet A700V686M006ATE028
C4 1
22µF ±20%, 6.3V X5R ceramic
capacitor (1206)
TDK C3216X5R0J226M
C5 1
47µF, 25V electrolytic capacitor
(6.3mm x 5.8mm)
Panasonic EEVFK1E470P
C6 1
0.0047µF ±10%, 250VAC X7R
ceramic capacitor (1825)
Murata GA355DR7GC472KY02L
DESIGNATION QTY DESCRIPTION
C7, C11 2
0.22µF ±10%, 50V X7R ceramic
capacitors (0805)
Murata GRM21BR71H224KA01B
C8, C10, C19 0 Not installed, ceramic capacitors
(0603)
C9 1
100pF ±2%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H101G
C12 1
15µF ±10%, 35V tantalum
capacitor (D)
Kemet T491D156K035AS
C13 1
1µF ±10%, 16V X7R ceramic
capacitor (0805)
TDK C2012X7R1C105KT
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX15000A
MAX15000A Evaluation Kit
2 _______________________________________________________________________________________
Component List (continued)
DESIGNATION
QTY
DESCRIPTION
C14 1
3900pF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H392K
C15 1
1µF ±10%, 25V X7R ceramic
capacitor (0805)
TDK C2012X7R1E105KT
C16 1
1µF ±10%, 50V X7R ceramic
capacitor (1206)
Murata GRM31MR71H105K
C17 0 Not installed, ceramic capacitor
(0805)
C18 1
0.1µF ±10%, 25V X7R ceramic
capacitor (0603)
Murata GRM188R71E104K
D1 1
40V, 10A Schottky diode
(POWERMITE 3)
Diodes Inc. SBM1040
D2 1
200V, 1.5A super-fast diode (SMD)
Vishay BYG20D
D3 0
Not installed, 250V, 250mA high-
voltage switching diode (SOD-123)
Central Semiconductor CMHD2003
recommended
D4 1
5.6V, 0.5W zener diode (SOD-123)
Diodes Inc. BZT52C5V6
D5 1 18V, 0.5W zener diode (SOD-123)
Diodes Inc. BZT52C18
D6 1
75V, 250mA high-speed diode
(SOT23)
Central Semiconductor CMPD914
D7 0
Not installed, 14V, 250mW zener
diode (SOD-323)
Central Semiconductor
CMDZ5244B recommended
DESIGNATION QTY DESCRIPTION
D8 1 40V, 0.5A Schottky diode (SOT23)
Zetex ZHCS500
JU1 1 2-pin header
L1 1 3A ferrite bead inductor (1806)
Fair-Rite 2518066007Y3
L2 1 100mA ferrite bead inductor (0805)
Fair-Rite 2508051027Y0
N1 1 200V, 1.2A n-channel MOSFET
(SO-8) IR IRF7464
R1 1 22.6kΩ ±1% resistor (0603)
R2 1 2.49kΩ ±1% resistor (0603)
R3 1 1.37MΩ ±1% resistor (0805)
R4 1 51.1kΩ ±1% resistor (0805)
R5 1 0.600Ω ±1% power resistor (1206)
IRC LRC-LR1206-01-R600-F
R6 1 33kΩ ±5% resistor (1206)
R7, R12 2 1.2kΩ ±5% resistors (1206)
R8 0 Not installed, resistor (1206)
R9 1 75kΩ ±1% resistor (0603)
R10 1 4.7Ω ±5% resistor (0805)
R11 1 100Ω ±5% resistor (0603)
R13 1 10kΩ ±5% resistor (0805)
R14 1 14.3kΩ ±1% resistor (0805)
R15 1 750Ω ±5% resistor (0603)
T1 1
28µH, 10W, 1:0.536:0.214:0.429
turn 350kHz transformer
(10-pin gull wing)
Coiltronics CTX03-17492-R
U1 1 MAX15000AEUB+ (10-pin µMAX)
— 1 Shunt, JU1
— 4 Rubber bumpers
— 1 MAX15000A EV kit PC board
Evaluates: MAX15000A
MAX15000A Evaluation Kit
_______________________________________________________________________________________ 3
Component Suppliers
SUPPLIER PHONE WEBSITE
Central Semiconductor 631-435-1110 www.centralsemi.com
Cooper-Coiltronics 561-752-5000 www.cooperet.com
Dale-Vishay 402-564-3131 www.vishay.com
Diodes Inc. 805-446-4800 www.diodes.com
Fair-Rite Products 845-895-2055 www.fair-rite.com
International Rectifier 310-322-3331 www.irf.com
IRC 361-992-7900 www.irctt.com
Kemet 864-963-6300 www.kemet.com
Murata 770-436-1300 www.murata.com
Panasonic 714-373-7366 www.panasonic.com
TDK 847-803-6100 www.component.tdk.com
Vishay 402-563-6325 www.vishay.com
Zetex USA 631-543-7100 www.zetex.com
Quick Start
Required Equipment
• 36V to 72V power supply capable of providing up to 1A
• Two voltmeters
• 22µF, 100V bulk storage capacitor to be connected
to the input terminals of the EV kit
The MAX15000A EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed.
Outputs
1) Connect a voltmeter to the VOUT1 SGND pads.
2) Connect a second voltmeter to the VOUT2 and
SGND pads.
3) Connect a 750mA load to VOUT1 and a 50mA load
to VOUT2.
4) Verify that a shunt is not installed across the pins of
jumper JU1 (SHDN).
5) Connect the power supply’s positive terminal to the
+VIN pad. Connect the power supply’s ground to
the -VIN pad.
6) Turn on the power supply above +36V and verify that
the voltmeter at VOUT1 reads approximately +5V.
7) Verify that the voltmeter at VOUT2 reads approxi-
mately +15V.
The maximum current for each output should be limited
to less than 1.5A for VOUT1 and 100mA for VOUT2.
For instructions on selecting the feedback resistors for
other output voltages, see the Evaluating Other Output
Voltages, Current Limits, and Undervoltage Lockouts
section.
Detailed Description
The MAX15000A EV kit is a 9W, isolated flyback DC-DC
converter that provides a +5V output and a +15V output.
The +5V output, VOUT1, can provide up to 1.5A and the
+15V output, VOUT2, can provide up to 100mA. The cir-
cuit can be powered from a +36V to +72V or a -36V to
-72V DC source. The user must supply at least 22µF of
bulk storage capacitance at the input terminals (+VIN,
-VIN). The capacitor should be rated for 100V and be
able to carry approximately 200mA of ripple current.
The flyback DC-DC converter achieves up to 81% effi-
ciency. The single-transistor topology and primary-side
regulation provide for a low-cost design by eliminating
Note: Indicate that you are using the MAX15000A when contacting these component suppliers.
Evaluates: MAX15000A
the need for an optocoupler and shunt reference on the
secondary side. The MAX15000A EV kit provides cycle-
by-cycle, primary-side current-limit protection. Current-
sense resistor, R5, senses the current through the
transformer’s (T1) primary winding, switching transistor
(N1), and turns off the transistor when the trip level of
1V is reached. The surface-mount transformer provides
galvanic isolation up to 1500V for both outputs. The
MAX15000A EV kit features PC board pads for an RCD
snubber network (R8, C10, D3) to minimize leakage
energy ringing and clamp the voltage at the drain of
MOSFET N1 during switching (with most MOSFETs this
snubber circuit can be eliminated).
Primary-side regulation through feedback resistors R1
and R2, rectifier D6, and transformer T1 tertiary windings
provide ±5% regulation for the 5V output set point.
Resistors R7 and R12 are adjusted to preload the tertiary
winding for the desired +5V ouput set point and regula-
tion. UVLO provides controlled turn-on and shutdown
during brownouts, powering up, or powering down. The
UVLO settings can be changed by replacing resistor R3.
Startup resistor R6 and reservoir capacitor C16 enable
the MAX15000A to start up within approximately 37ms.
The digital soft-start allows the output voltage to slowly
ramp up in a controlled manner within 6ms.
The MAX15000A controller switches at a fixed 350kHz
frequency and is set by resistor-capacitor networks
R14, R15/C18, and C19. The switching duty cycle is
varied to control energy transfer to the isolated outputs.
The maximum duty cycle is 50% for the EV kit’s discon-
tinuous current-mode flyback design.
Shutdown Mode (Jumper and Remote
Control Methods)
The MAX15000A EV kit features two methods to shut
down the flyback DC-DC converter. Jumper JU1 can
be used to shut down the flyback DC-DC converter. An
alternate method, remote control shutdown, can be
done with a user-supplied open-collector/drain transis-
tor or relay contact connected to the SHDN and -VIN
pads of the EV kit. Table 1 lists the shutdown mode.
Evaluating Other Output Voltages,
Current Limits, and Undervoltage Lockouts
VOUT1 and VOUT2 Output Voltages
The MAX15000A EV kit’s outputs VOUT1 and VOUT2 are
set to +5V and +15V, respectively, by the transformer
T1 tertiary windings, the transformer’s respective sec-
ondary output windings, and the resistor-divider R1 and
R2. To generate scaled output voltages other than +5V
(+4.2V to +6.8V) and +15V (+12.3V to +20.2V), select
different voltage-divider resistors (R1, R2). Resistor R2
is typically chosen to be less than 5kΩ. When evaluat-
ing other output voltages, verify that the secondary
outputs’ components affected by increased voltage
are rated for the appropriate voltage. Components
C3, C4, C13, and D4 of VOUT1 and components C5,
C15, and D5 should have their respective voltage
rating evaluated. Using the desired scaled output volt-
ages, resistor R1 is then found by the following equation:
R1 = [[{(VOUT1 - VVD1) x NT/ N1} - VVD6] / VFB -1] x R2
where VOUT1 is the +5V output,
NT= 15 is the transformer’s tertiary turns
N1= 6 is the transformer’s secondary VOUT1, +5V out-
put turns
VFB = 1.23V is the MAX15000A reference voltage
VVD6 = 1.0V is the circuit’s tertiary winding, high-speed
diode D6 forward voltage drop
VVD1 = 0.45V (typ) is the circuit’s secondary-side
Schottky diode D1 forward voltage drop at 1.5A
Both output voltages will be scaled up or down since
the respective transformer’s secondary output turns set
the actual voltage. Additionally, the maximum current
for each output should be limited to less than 1.5A for
VOUT1 and 100mA for VOUT2.
MAX15000A Evaluation Kit
4 _______________________________________________________________________________________
SHUNT
LOCATION
MAX15000A
UVLO/EN PIN
MAX15000A
OUTPUT
Open UVLO resistors R3 and R4
determine startup voltage
MAX15000A
enabled
Installed
Pulled low to -VIN
Shutdown mode
Table 1. Jumper JU1 Shutdown Mode
Current Limiting
The EV kit features current limiting for the transformer’s
primary current. The MAX15000A IC turns off switching
MOSFET N1 when the voltage at the MAX15000A CS
pin reaches 1V. Current-sense resistor R5 (0.6Ω) limits
the transformer peak primary current to 1.67A (1V / 0.6Ω
= 1.67A). This limits the average short-circuit current on
the secondary outputs typically to 1.42A (average with
IOUT2 = 100mA) and 0.52A (average with IOUT1 = 1.5A)
for VOUT1 and VOUT2, respectively. To evaluate a
lower current limit, current-sense resistor R5 must be
replaced with a different surface-mount resistor (1206
size) as determined by the following equation.
When considering the transformer’s primary input current:
R5 = (VSENSE / IPRIMARY)
where VSENSE = 1V and IPRIMARY is the transformer’s
maximum primary current.
Undervoltage Lockout (UVLO)
The MAX15000A EV kit features an accurate UVLO cir-
cuit that prevents operation below the programmed
input-supply start voltage. Resistors R3 and R4 set the
voltage at the MAX15000A’s UVLO/EN pin that deter-
mines the UVLO wake-up and shutdown levels, 1.23V
(typ) and 1.17V (typ), respectively. To evaluate other
wake-up and shutdown levels, replace resistor R3 with
another surface-mount resistor (0805 size). Refer to the
Undervoltage Lockout section in the MAX15000/
MAX15001 data sheet for instructions on selecting
resistor R3 as determined by the following equation:
R3 = ((VIN - VUVLO) / VUVLO) x R4
where VIN is the 36V to 72V supply voltage applied
between the +VIN and -VIN pads of the EV kit and
VUVLO = 1.23V (typ).
UVLO Flag (UFLG and FLG_PULL)
The MAX15000A EV kit features an open-drain UVLO
flag output at the UFLG PC board pad. The UFLG signal
can be used to indicate a UVLO condition has occurred.
A voltage source of up to 25V can be connected to the
PC board’s FLG_PULL pad, which, along with resistor
R13, pulls up the UFLG signal. Refer to the UVLO Flag
(UFLG) section in the MAX15000/MAX15001 data sheet
for instructions and additional information on using the
UFLG pin of the MAX15000A.
Evaluates: MAX15000A
MAX15000A Evaluation Kit
_______________________________________________________________________________________ 5
Evaluates: MAX15000A
MAX15000A Evaluation Kit
6 _______________________________________________________________________________________
Flyback Converter Waveforms
Figure 1. Efficiency vs. Output Current IOUT1 (+VIN = 48V)
VOUT1 REGULATION vs. IOUT1
IOUT1 (A)
VOUT1 (V)
1.20.90.3 0.6
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
4.0
0 1.5
VOUT2 = +15V, 100mA
VOUT2 = +15V, 25mA
VOUT2 REGULATION vs. IOUT2
IVOUT2 (A)
VOUT2 (V)
0.080.060.02 0.04
14.4
14.8
15.2
15.6
16.0
16.4
16.8
17.2
17.6
18.0
14.0
0 0.10
VOUT1 = +5V, 150mA
VOUT1 = +5V, 1.5A
Figure 2. Output Voltage Transient at Power-Up (+VIN = 48V,
Channel 1 = VOUT1 (IOUT1 = 150mA), Channel 2 = VOUT2
(IOUT2 = 25mA))
Figure 3. VOUT1 (+5V) Output Voltage Regulation Figure 4. VOUT2 (+15V) Output Voltage Regulation
Evaluates: MAX15000A
MAX15000A Evaluation Kit
_______________________________________________________________________________________ 7
MAX15000A
U1
+VIN
UFLG
-VIN
VOUT2
SGND
VOUT1
SGND
12
1
2
3
3
2
1
4
4
678
5T1 D2
D3
OPEN
D6
D8
D1
10
D7
OPEN
R12
1.2kΩ
7
9
8
6
C6
0.0047μF
250VAC
C3
68μF
6.3V
5T
12T D5 C15
1μF
D4
L1
C13
1μF
C4
22μF
6.3V
28T
28μH
15T
5
N1
IRF7464
R7
1.2kΩ
R8
OPEN
C10
OPEN
R5
0.600Ω
1%
R15
750Ω
C16
1μF
R6
33kΩ
C5
47μF
25V
L2
FB_P
IN
36V TO 72V
IN
+VIN
10
IN
NDRV
CS
GND
FB_P
RT
8
5
6
7
FB
COMP
UVLO/EN
UFLG
VCC
JU1
3
4
1
2
9
+VIN
C12
15μF
35V
R14
14.3kΩ
1%
C17
OPEN
C9
100pF
C14
3900pF
R4
51.1kΩ
R3
1.37MΩ
1%
R9
75kΩ
1%
R2
2.49kΩ
1%
R1
22.6kΩ
1%
R13
10kΩ
C8
OPEN
C7
0.22μF
C11
0.22μF
C19
OPEN
C18
0.1μF
R11
100Ω
FLG_PULL
SHDN
R10
4.7Ω
C2
1μF
100V
C1
1μF
100V
Figure 5. MAX15000A EV Kit Schematic
Evaluates: MAX15000A
MAX15000A Evaluation Kit
8 _______________________________________________________________________________________
Figure 6. MAX15000A EV Kit Component Placement Guide—Component Side
Figure 7. MAX15000A EV Kit PC Board Layout—Component 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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX15000A
MAX15000A Evaluation Kit
Figure 8. MAX15000A EV Kit PC Board Layout—Solder Side