MAXIM MAX1534EVKIT

19-2700; Rev 0; 12/02
MAX1534 Evaluation Kit
Features
♦ Triple-Output Power Supply
5.0V at 500mA (typ)
3.3V at 160mA
1.8V at 160mA
♦ Integrated Power MOSFETs
♦ 4.5V to 24V Input Supply Range
♦ Adjustable Inductor Current Limit
♦ Fixed or Adjustable Outputs
♦ Power-OK (POK) Output
♦ 3.5µA Shutdown Supply Current (typ)
♦ Surface-Mount Construction
♦ Fully Assembled and Tested
Ordering Information
PART
MAX1534EVKIT
TEMP RANGE IC PACKAGE
0°C to +70°C
16 Thin QFN 4mm × 4mm
Component List
DESIGNATION
QTY
C1
1
C2
1
C3, C5, C6
D1
10µF ±20%, 25V X7R ceramic
capacitor (1812)
TDK C4532X7R1E106M
47µF ±20%, 6.3V X5R ceramic
capacitor (1210)
TDK C3225X5R0J476M
DESIGNATION
L1
QTY
1
DESCRIPTION
15µH, 1A inductor
Sumida CDRH6D38-150
R1–R6
0
Not installed (0603)
R7
1
100kΩ ±5% resistor (0603)
R8, R9
0
Not installed (2010)
R10, R11
0
Not installed (0805)
2.2µF ±20%, 10V X5R ceramic
capacitors (0805)
TDK C2012X5R1A225M
JU1, JU2
2
Jumpers, SIP-3, 3-pin headers (SIP-3)
JU3
0
Not installed (SIP-3)
JU4
1
Jumper, 2 × 3 pin header
1
MAX1534ETE (16-pin thin QFN)
1
0.01µF ±20%, 25V X7R ceramic
capacitor (0402)
TDK C1005X7R1E103M
U1
None
3
Shunts
None
1
MAX1534 PC board
1
1A, 30V, Schottky diode (SMA)
Nihon EP10QY03
3
C4
DESCRIPTION
Component Suppliers
SUPPLIER
PHONE
FAX
WEBSITE
Nihon
81-33343-3411
81-33342-5407
www.niec.co.jp
Sumida
847-545-6700
847-545-6720
www.sumida.com
TDK
847-803-6100
847-390-4405
www.component.tdk.com
Note: Please indicate that you are using the MAX1534 when contacting these component suppliers.
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX1534
General Description
The MAX1534 evaluation kit (EV kit) is a fully assembled
and tested surface-mount circuit board that demonstrates the MAX1534 triple-output keep-alive power supply IC. The MAX1534 integrates one high-performance
step-down converter and two low-dropout regulators
(LDOs). The step-down converter is configured for 5.0V
and provides up to 500mA. The first and second LDOs
are configured for 3.3V and 1.8V at currents up to
160mA each. Power management functions include an
accurate shutdown input and power-OK (POK) output.
The EV kit also allows for adjustable output voltages by
including extra pads for feedback resistors.
Evaluates: MAX1534
MAX1534 Evaluation Kit
Quick Start
Recommended Equipment
• One variable DC power supply capable of supplying
between 4.5V and 24V at 1A
• Five voltmeters
Procedure
The MAX1534 EV kit is fully assembled and tested.
Follow the steps below to verify board operation. Do
not turn on the power supply until all connections
are completed:
1) Set the variable DC power supply to any voltage
between 4.5V and 24V.
2) Ensure that the variable DC power supply is turned
off.
3) Ensure that shunts are placed across pins 1-2 of
jumpers JU1 and JU2.
4) Ensure that a shunt is placed across pins 3-4 of
jumper JU4.
5) Connect a voltmeter across the IN pad and the
GND pad (located beside the OUT3 pad) to monitor
the input voltage.
6) Connect a voltmeter across the OUT1 pad and the
GND pad (located beside the OUT1 pad) to monitor
the OUT1 voltage (3.3V).
7) Connect a voltmeter across the OUT2 pad and the
GND pad (located beside the LDOIN pad) to monitor the OUT2 voltage (1.8V).
8) Connect a voltmeter across the OUT3 pad and the
GND pad (located below the OUT3 pad) to monitor
the OUT3 voltage (5.0V).
9) Connect a voltmeter across the POK pad and the
GND pad (located above the LDOIN pad) to monitor the POK voltage.
10) Turn on the variable DC power supply.
11) Verify that the voltage at OUT1 is 3.3V.
12) Verify that the voltage at OUT2 is 1.8V.
13) Verify that the voltage at OUT3 is 5.0V.
nal feedback network. The MAX1534 also features two
additional internal LDOs that are set to 1.8V and 3.3V
with output currents of 160mA each. The outputs of the
buck converter and the LDO regulators can be adjusted by adding feedback resistors R1 through R6. For
instructions on adjusting the output voltage, see the
Adjusting the Output Voltages section.
The default configuration of the MAX1534 EV kit drives
the input to the LDOs with the output of the buck converter (OUT3). If the output of the buck converter
(OUT3) is configured lower than the outputs of the
LDOs (OUT1 or OUT2), LDOIN must be driven by a
separate source (see Using an Alternative LDO Source
Supply).
Shutdown Control
The MAX1534 has an active-low shutdown control input
that enables/disables all three power outputs. Jumper
JU1 selects the circuit operating modes: shutdown or
normal operation. Remove the shunt when driving SHDN
with an external signal. See Table 1 for shunt positions.
The MAX1534 EV kit can be programmed to shut down
Table 1. Shutdown Selection
JUMPER
SHUNT
POSITION
JU1
1-2*
JU1
2-3
MAX1534 outputs
Connected
disabled. POK is low
to GND
impedance.
*Default configuration: JU1 (1-2).
when the input voltage drops below a desired minimum
voltage (VIN(MIN)) by installing resistors R10 and R11,
and removing the shunt on JU1. Calculate these resistor
values using the following equation:
 VIN (MIN) 
R11 = R10 
− 1
 VSHDN

Detailed Description
2
DESCRIPTION
MAX1534 outputs
Connected enabled. POK is high
to IN
impedance when all
outputs are in regulation.
14) Verify that the voltage at POK is 5.0V.
The MAX1534 EV kit provides multiple output voltages
(5.0V, 3.3V, and 1.8V) from a 4.5V to 24.0V input. The
buck-converter section of the EV kit delivers up to
500mA and operates up to 100% duty cycle. The EV kit
utilizes the MAX1534 IC, and the circuit regulates the
buck converter output voltage to 5.0V without an exter-
SHDN PIN
where:
VSHDN = 1.0V
R10 = 100kΩ
VIN(MIN) = desired minimum input voltage
_______________________________________________________________________________________
MAX1534 Evaluation Kit
Table 2. Inductor Current-Limit Selection
JUMPER
SHUNT
POSITION
ILIM PIN
INDUCTOR
CURRENT LIMIT
(mA)
JU2
1-2*
Connected
to IN
1000
Connected
to GND
500
JU2
2-3
*Default configuration: JU2 (1-2).
Selecting the POK Active-High Output
Voltage
The POK pin of the MAX1534 indicates the status of the
output voltages. Monitor this voltage at the POK pad.
The POK pin is pulled up with a 100kΩ resistor through
jumper JU4 to one of the three outputs. See Table 3 for
shunt positions.
Table 3. POK Output Selection
JUMPER
SHUNT
POSITION
JU4
1-2
POK pin pulled up to OUT2
(1.8V default)
JU4
3-4*
POK pin pulled up to OUT3
(5.0V default)
5-6
POK pin pulled up to OUT1
(3.3V default)
JU4
DESCRIPTION
*Default configuration: JU4 (3-4).
Adjusting the Output Voltages
The MAX1534 EV kit circuit is configured to regulate the
output voltages to preset values by connecting the
PRESET pin to ground. The outputs can be adjusted to
different voltages by cutting open the PC board short
Table 4. PRESET Shunt Positions
JUMPER
SHUNT
POSITION
PRESET
PIN
JU3
1-2
Connected
to IN
Adjustable output
mode
JU3
2-3*
Connected
to GND
Fixed output mode
DESCRIPTION
*Default configuration: JU3 (2-3) shorted by PC board trace.
between pins 2-3 of JU3, shorting pins 1-2 of JU3, and
installing resistors R1 through R6. Refer to the instructions
below for resistor selection. See Table 4 for PRESET
shunt positions.
To adjust the output voltages of the MAX1534 EV kit,
follow the directions below:
1) Cut the trace between pins 2 and 3 of jumper JU3.
2) Install a 3-pin header in position JU3.
3) Place a shunt across pins 1 and 2 of jumper JU3.
4) Cut the trace between the pads of resistor R1, R4,
and R6.
5) Install resistors in locations R1 through R6 (the
resistor values are calculated using the following
equations).
To set the output voltage on OUT1, choose R3 as follows:
V

R3 = R4 ×  OUT1 − 1
 VFB1

where:
VOUT1 = desired output voltage at OUT1 (from 1V to
LDOIN)
VFB1 = 1.00V
R4 = 100kΩ
To set the output voltage on OUT2, choose R5 as follows:
V

R5 = R6 ×  OUT2 − 1
 VFB2

where:
VOUT2 = desired output voltage at OUT2 (from 1V to
LDOIN)
VFB2 = 1.00V
R6 = 100kΩ
_______________________________________________________________________________________
3
Evaluates: MAX1534
Adjustable Inductor Current Limit
The MAX1534 EV kit can operate at different current
limits. Jumper JU2 selects the MAX1534’s maximum
internal switch current limit. The EV kit’s default setting
allows a maximum 1000mA internal switch current. To
change the switch current limit to 500mA, move the
shunt on jumper JU2 to pins 2-3. Changing the current
limit requires inductor L1 and output capacitor C2 to be
replaced. Refer to the Recommended Components
table in the MAX1534 data sheet. Remove the shunt
when driving ILIM with an external signal. See Table 2
for shunt positions.
Evaluates: MAX1534
MAX1534 Evaluation Kit
OUT1
OUT1
11
R3
OPEN
GND
C5
2.2µF
13
OUT2
FB1
SHDN
IN
6
7
C1
10µF
R11
OPEN
1
JU1
1
1
JU2
R5
OPEN
14
PULLUP
ILIM
OUT2
PRESET
OUT3
PULLUP
POK
R7
100kΩ
LX
12
C4
0.01µF
1
JU3
15
FB2
LDOIN
2
4
R9
SHORT
(PC TRACE)
R6
SHORT
(PC TRACE)
LX
POK
BP
FB3
GND
3
ILIM
2
3
MAX1534
C6
2.2µF
GND
SHDN
2
3
R10
OPEN
U1
9
GND
OUT2
PULLUP
OUT1
IN
R4
SHORT
(PC TRACE)
OUT2
1 JU4 2
3
4
5
6
IN
OUT1
SHORT
2 (PC TRACE)
3
LDOIN
10
C3
2.2µF
5
8
16
R8
SHORT
(PC TRACE)
D1
OUT3
L1
15µH
OUT3
C2
47µF
R1
SHORT
(PC TRACE)
GND
R2
OPEN
Figure 1. MAX1534 EV Kit Schematic
To set the output voltage on OUT3, choose R1 as follows:
V

R1 = R2 ×  OUT3 − 1
 VFB3

where:
VOUT3 = desired output voltage at OUT3 (from 1V to IN)
VFB3 = 1.00V
R2 = 100kΩ
Note: If OUT3 is set higher than 5.5V, OUT3 must be
disconnected from LDOIN and POK.
The voltage at OUT3 must be at least 240mV higher
than the voltages at OUT1 and OUT2. If the voltage at
OUT3 is lower than either of the voltages at OUT1 and
OUT2, the input to the LDOs must be driven by a separate power source (see Using an Alternative LDO
Source Supply section).
Note: Adjustable operation may require replacement of
capacitors with higher voltage ratings.
Note: Do not pull up POK above LDOIN.
4
Using an Alternative LDO Source Supply
The buck-converter output (OUT3) is the default power
source for the two LDOs. If the output voltages at either
OUT1 or OUT2 are reconfigured for a voltage greater
than OUT3, the input to the MAX1534 internal LDOs
must be driven by an external source. To drive the
LDOs with an external source, follow the directions
below:
1) Cut the PC board trace shorting the pads of resistor
R8.
2) Connect an external 0.5A source to the pads
marked LDOIN and GND.
3) Ensure that the external source is greater than 2.5V,
at least 240mV higher than OUT1 or OUT2
(whichever is greater), and does not exceed 5.5V.
_______________________________________________________________________________________
MAX1534 Evaluation Kit
Figure 3. MAX1534 EV Kit PC Board Layout—Component Side
Figure 4. MAX1534 EV Kit PC Board Layout—Solder Side
Figure 5. MAX1534 EV Kit Component Placement Guide—
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
Evaluates: MAX1534
Figure 2. MAX1534 EV Kit Component Placement Guide—
Component Side