19-1985; Rev 1; 1/02
MAX1800 Evaluation Kit
General Description
The MAX1800 evaluation kit (EV kit) accepts 1.8V to
5.5V battery voltages and provides all of the output volt-
ages required in digital still cameras (DSC). The EV kit
consists of the MAX1800 multi-output master converter
and the MAX1801 slave step-up converter.
The EV kit provides 10 separate output voltages. The
MAX1800 provides one main-system step-up converter
(3.3V/400mA), one linear regulator for the DSP core
(1.8V/200mA), one step-up converter for the backlight
(7V/100mA), three flyback outputs for the CCD
(14.3V/10mA, 5V/50mA, -8.15V/10mA), and three fly-
back outputs for the LCD (13.85V/10mA, 5V/50mA,
-16.23V/10mA). In addition, the MAX1801 provides one
step-up converter for the motor (5V/500mA).
The EV kit’s outputs are adjustable and are suitable for
applications running from 2- or 3-cell alkaline, NiCd, or
NiMH batteries or from a single lithium-on (Li+) battery.
Features
o
10 Outputs
One Synchronous Rectified Step-Up Converter
Two Step-Up Converters
One Low-Dropout Linear Regulator Output
Six Flyback Outputs
o
1.8V to 5.5V Input Voltage Range
o
All Converters Synchronized to Single Oscillator
o
100kHz to 1MHz Switching Frequency
o
Main Power-OK Output
o
Independent Shutdown of Each Converter
o
Short-Circuit-Protected Flyback Outputs
o
Soft-Start on Each Output
o
Fully Assembled and Tested
Evaluates: MAX1800/MAX1801
Ordering Information
PART
MAX1800EVKIT
TEMP RANGE
0°C to +70°C
IC PACKAGE
32 TQFP, 8 SOT23
Component List
DESIGNATION
C1, C22
QTY
2
DESCRIPTION
10µF, 10V ceramic
capacitors (1210)
TDK C3225X5R1A106M
100pF, ceramic capacitor
(0603)
0.1µF ceramic capacitors
(0603)
4.7µF, 10V ceramic
capacitors (1206)
TDK C3216X5R1A475M or
Taiyo Yuden
LMK316BJ475ML
1000pF ceramic capacitors
(0603)
1µF, 25V ceramic capacitors
(1206)
TDK C3216X7R1E105KT
4.7µF, 6.3V ceramic
capacitor (0805)
TDK C2012X5R0J475K
DESIGNATION
C17
QTY
1
DESCRIPTION
220µF, 10V, 100mΩ low-ESR
(E case)
AVX TPSE227M010R0100
47µF, 6.3V, 100mΩ low-ESR
(C case)
Sanyo 6TPA47M
0.01µF ceramic capacitor
(0603)
PN junction diodes (SOT323)
Central Semiconductor
CMSD-4448
Schottky diodes (SOT323)
Central Semiconductor
CMSSH-3
Schottky diodes (SOD-123)
Motorola MBR0520L or
Fairchild Semiconductor
MBR0520L
Schottky diode (CASE 403A-
03 SMB)
Motorola MBRS130LT3
C2
C3, C15, C21
1
3
C19
1
C24
1
C4, C18
2
D1, D4, D6
3
C5−C8, C20
5
D2, D3, D5, D9
4
C9−C14
6
D7, D8
2
C16
1
D10
1
________________________________________________________________
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.
MAX1800 Evaluation Kit
Evaluates: MAX1800/MAX1801
Component List (continued)
DESIGNATION
JU1−JU6
JU7− JU12
L1
L2
QTY
6
6
1
1
DESCRIPTION
3-pin headers
2-pin headers
1.4µH inductor
Sumida CR43-1R4
10µH inductor
Sumida CDRH6D38-100
0.5µH inductor
Sumida CR43 Type Sample
4757-T019
N-channel MOSFETs
Fairchild Semiconductor
FDN337N
P-channel MOSFET
Fairchild Semiconductor
NDS336P
200Ω
±5%
resistors (1206)
40.2kΩ
±1%
resistor (0603)
Shorted in the PC board
layout (0402)
(not installed)
U1
U2
None
1
1
12
DESIGNATION
R7, R8, R9, R27
R11, R16, R24
R18
R20
R21
R23
R35, R36, R40,
R41, R44, R45
R39
R46
T1
QTY
4
3
1
1
1
1
6
1
1
1
DESCRIPTION
10kΩ
±5%
resistors (0402)
301kΩ
±1%
resistors (0603)
44.2kΩ
±1%
resistor (0603)
4.7Ω
±5%
resistor (0402)
165kΩ
±1%
resistor (0603)
1MΩ
±5%
resistor (0402)
3kΩ
±5%
resistors (1206)
750Ω
±5%
resistor (1206)
100kΩ
±5%
resistor (0402)
Transformer
Sumida “Sample Number”:
6333-T330
Transformer
Sumida “Sample Number”:
6333-T329
MAX1800EHJ (32-pin TQFP)
MAX1801EKA (8-pin SOT23)
Shunts
L3
1
Q1, Q2, Q3, Q5
4
Q4
R37, R38, R42,
R43
R1
R2, R29, R31, R33
1
T2
1
4
1
4
R3, R12−R15,
R26, R28, R30,
R32, R34
R4
R5, R10, R17,
R19, R22, R25
R6
10
1
6
1
Open, not installed (0402)
464kΩ
±1%
resistor (0603)
100kΩ
±1%
resistors (0603)
200kΩ
±5%
resistor (0402)
graph in the
Typical Operating Characteristics
in the
MAX1800 data sheet before loading MAIN.
3) Make sure jumpers JU7–JU12 are connected if no
external loads are attached to the OUT1A, OUT1B,
OUT1C, OUT2A, OUT2B, and OUT2C outputs.
4) Attach a 1.8V to 5.5V battery or power supply to IN.
5) Using the DVM, measure the voltage at MAIN, LDO,
OUT1_, OUT2_, OUT3 and OUT4.
Detailed Description
Quick Start
Recommended Equipment
• 1.8V to 5.5V battery or power supply
• Digital voltmeter (DVM)
The main output (MAIN) powers the MAX1800’s internal
circuitry. MAIN must be regulated before any of the
other outputs function.
To enable MAIN, place jumper JU2 in the 1-2 position.
Apply 1.8V to 5.5V between IN and GND. The voltage
between MAIN and GND should be approximately 3.3V
if IN is <3.3V. Because the IC is powered from MAIN,
the IC does not work at maximum efficiency until MAIN
is in regulation. Thus, at low battery voltages and heavy
loads, MAIN may not have sufficient power to start. The
output current capability shown in Table 1 is valid for
input voltages down to 1.8V. The circuit operates for
Connections and Setup
1) Make sure jumpers JU1–JU6 are connected in the 1-
2 (ON) position. This ensures that all converters will
turn-on at power-up.
2) Before loading any output, check the output voltage
and output current capability shown in Table 1. See
the Startup Input Voltage vs. MAIN Output Current
2
_______________________________________________________________________________________
MAX1800 Evaluation Kit
Table 1. Output Voltage and Current
Capability
LABEL
MAIN
LDO
OUT1A
OUT1B
OUT1C
OUT2A
OUT2B
OUT2C
OUT3
OUT4
VOLTAGE/CURRENT
3.3V at 400mA
1.8V at 200mA
14.3V at 10mA
5V at 50mA
-8.15V at 10mA
13.85V at 10mA
5V at 50mA
-16.23V at 10mA
7V at 100mA
5V at 500mA
3 (OFF) position. To enable/disable the output voltages
using an external signal, see the
Logic Control of the
Output Voltages
section.
If a different set of output voltages is required, see the
Setting the Flyback Circuit Voltages (OUT1_ and
OUT2_)
section.
Evaluates: MAX1800/MAX1801
OUT2_ (Flyback Outputs)
The voltages at OUT2_ are typical of LCD bias volt-
ages. The output voltages are 13.85V/10mA, 5V/50mA,
and -16.23V/10mA. These voltages are generated
through a custom flyback transformer. OUT2B (5V) is
used to regulate the flyback circuit. The other output
voltages (13.85V and -16.23V) are controlled by the
turns-ratio of the flyback transformer. If the 13.85V and
-16.23V outputs are not loaded at the fixed 10mA load,
then the output voltage will change from the nominal
loaded output voltage. Loads are included on the
MAX1800 EV kit by shorting jumpers JU7 through
JU12. If external loads are used, disable the built-in
loads by removing these jumpers.
To enable OUT2_, place jumper JU5 to the 1-2 (ON)
position. To disable OUT2_, place jumper JU5 to the 2-
3 (OFF) position. To enable/disable the output voltages
using an external signal, see the
Logic Control of the
Output Voltages
section.
If a different set of output voltages is required, see the
Setting the Flyback Circuit Voltages (OUT1_ and
OUT2_)
section.
input voltages below 1.8V but with reduced output cur-
rent capability. Refer to the MAX1800 data sheet for the
minimum allowable input voltage for the part to start at
a given load.
When the MAIN output is in regulation, the MAIN_OK
output will be pulled up to the MAIN output voltage. If
the MAIN_OK output is low (near ground), MAIN is not
in regulation.
LDO Output
The LDO output is linearly regulated from MAIN to 1.8V.
Note that the load current on LDO is produced from
MAIN. Drawing more than 200mA out of LDO reduces
the current capability at MAIN.
To enable LDO, place jumper JU3 in the 1-2 (ON) posi-
tion.
OUT3
The voltage at OUT3 is typical of that required by a
CCFL backlight inverter. To enable OUT3, place jumper
JU6 to the 1-2 (ON) position. Place the external load
between OUT3 and GND. To change the output voltage
of OUT3, see the
Setting the Step-Up Output Voltage
(OUT3 and OUT4)
section.
OUT3 can be configured to drive a white LED backlight
instead of a CCFL backlight.
OUT1_ (Flyback Outputs)
The voltages at OUT1_ are typical of CCD bias volt-
ages. The output voltages are 14.3V/10mA, 5V/50mA,
and -8.15V/10mA. These voltages are generated
through a custom flyback transformer. OUT1B (5V) is
used to regulate the flyback circuit. The other output
voltages (14.3V and -8.15V) are controlled by the turns-
ratio of the flyback transformer. If the 14.3V and -8.15V
outputs are not loaded at the fixed 10mA load, then the
output voltage will change from the nominal loaded out-
put voltage. Loads are included on the MAX1800 EV kit
by shorting jumpers JU7 through JU12. If external
loads are used, disable the built-in loads by removing
these jumpers.
To enable OUT1_, place jumper JU4 to the 1-2 (ON)
position. To disable OUT1_, place jumper JU4 to the 2-
OUT4
The voltage at OUT4 is a general-purpose 5V output
that can be used for powering a small motor or other
peripheral circuitry and can supply up to 500mA. To
enable OUT4, place jumper JU1 to the 1-2 (ON) posi-
tion. Place the external load between OUT4 and GND.
To change the output voltage of OUT4, see the
Setting
the Step-Up Output Voltage (OUT3 and OUT4)
section.
_______________________________________________________________________________________
3
MAX1800 Evaluation Kit
Evaluates: MAX1800/MAX1801
Customizing the
MAX1800 EV Kit
Setting the Main Output Voltage
MAIN is set by a voltage divider, which drops the out-
put voltage to the 1.25V feedback threshold voltage. To
change the 3.3V setting of MAIN, change the resistor
divider ratio by changing R21. Use:
R21 = 80kΩ / V
✕
( V
MAIN
- 1.25V )
The MAIN output voltage may be set to any voltage
between 2.7V and 5.5V. For additional information, see
the MAX1800 data sheet.
the transformer manufacturer for details. Typically the
highest power, positive voltage output of the flyback
transformer is fed back to the controller. To change the
regulated output voltage, use a different resistor in the
voltage divider. Table 2 lists the resistors used for each
output. Leave the resistors off (open) for unregulated
outputs.
For a given output voltage, the resistor value (Table 2) is:
R = 80kΩ / V
✕
( V
OUT
- 1.25V )
Setting the Step-Up Output Voltage (OUT3
and OUT4)
The output voltage of the step-up circuit voltages
(OUT3 and OUT4) may be set to any voltage above
1.25V. Note that if the battery voltage is greater than
the step-up regulation voltage, the output voltage will
rise above the regulation voltage. To set the output volt-
age, choose the voltage divider resistors. For OUT3,
choose:
R4 = 80kΩ / V
✕
( V
OUT3
- 1.25V )
For OUT4, choose:
R24 = 80kΩ / V
✕
( V
OUT4
- 1.25V )
Setting the LDO Output Voltage
The LDO output voltage is set by a voltage divider,
which drops the output voltage to the 1.25V feedback
threshold voltage. To change the 1.8V setting of LDO,
change the resistor divider ratio by changing R18. Use:
R18 = 80kΩ / V
✕
( V
LDO
- 1.25V )
The LDO output voltage may be set to any voltage
between 1.25V and 5.5V but must remain less than the
voltage at MAIN when powered from MAIN. The
MAX1800 EV kit is configured so that MAIN powers the
LDO input; however, opening up the short across R33
and shorting R34 will allow LDO to be powered from IN.
Setting the Maximum Duty Cycle
DCON1, DCON2, and DCON3 set the maximum duty
cycle for controllers 1, 2, and 3, respectively. A resistor
divider from REF to DCON_ sets the corresponding
maximum duty cycle up to 90%. The EV kit has DCON_
shorted to REF, producing a default duty cycle of 84%.
See the MAX1800 data sheet for additional information.
Setting the Flyback Circuit Voltages
(OUT1_ and OUT2_)
A flyback circuit generates OUT1_ and OUT2_. This
allows multiple, positive, or negative voltages to be
generated by a single converter and allows the volt-
ages to drop to 0V when the converter is disabled. The
transformer must be designed for a given set of output
voltages.
On the flyback circuits, only a single output voltage is
used to regulate all the voltages. All other voltages are
controlled by the turns-ratio of the transformer. If anoth-
er set of output voltages is required, a transformer with
a different secondary turns-ratio must be used. Consult
Setting the Switching Frequency
All of the switching regulators are synchronized to a
single oscillator frequency. The oscillator capacitor
(C2) is charged through R1 and discharged internally
by the MAX1800. The EV kit is designed to operate at
440kHz with MAIN set to 3.3V. If a different MAIN volt-
age is used, or if a different oscillator frequency is
desired, change resistor R1 or capacitor C2. Consult
the MAX1800 data sheet for the correct values to use
for R1 and C2.
Logic Control of the Output Voltages
Table 2. Flyback Converter Feedback
Resistors
OUTPUT
OUT_A
OUT_B
OUT_C
OUT1_
R13
R11
R12
OUT2_
R14
R16
R15
Each controller may be independently turned off or on
using jumpers (JU1–JU6) or with logic voltages. To
control an output using an external logic signal, remove
the ON/OFF jumper for that output, and place the con-
trol signal on the corresponding ON_ pad. To enable
the output, make sure that the voltage of the control
signal at the corresponding ON_ pad is >1.6V. To dis-
able it, make sure the voltage at the corresponding
ON_ pad is <0.3V.
4
_______________________________________________________________________________________
MAX1800 Evaluation Kit
Also, note that the voltages at MAIN, OUT3, and OUT4
will drop slightly below the battery voltage when OFF,
due to the DC current path through the inductor and
output rectifier. For the step-up outputs, a switch may
be added between the output voltage and the load to
disconnect them while the output is disabled.
Component Suppliers
SUPPLIER
AVX
Central
Semiconductor
Fairchild
Semiconductor
Motorola
Sumida
Taiyo Yuden
TDK
PHONE
803-946-0690
631-435-1110
408-721-2181
602-303-5454
847-956-0666
408-573-4150
847-803-6100
FAX
803-626-3123
631-435-1824
408-721-1635
602-994-6430
847-956-0702
408-573-4159
847-803-6296
Evaluates: MAX1800/MAX1801
High Input Voltage Operation
The MAIN output is designed to operate with an input
voltage above or below the output regulation voltage.
Since MAIN is a step-up converter, when the input volt-
age is above the regulation voltage, the output will be
nearly that of the input voltage. If the input battery volt-
age ranges above and below the regulation voltage,
follow the MAIN output with the LDO output to form a
step-up/step-down regulator. In this case, when the
battery voltage is low, the step-up converter raises the
battery voltage to the regulation voltage. When the bat-
tery voltage is above the regulation voltage, the LDO
regulator controls the output voltage.
For high input voltages, if the power is applied abruptly,
the MAIN output capacitor charges quickly, causing
the L2 inductor current to rise above the 2A current
limit. To prevent damage to the MAX1800, diode D10 is
used to charge main output capacitor C17, preventing
excessive current in the inductor. Components R46,
C24, and D9 delay turn-on of the MAIN converter when
power is applied. This prevents damage to the switch-
es caused by switching with excessive inductor current
at turn-on. If the MAX1800 is used exclusively with low
input voltage, components R46, C24, D9, and D10 may
be omitted.
Note:
Please indicate that you are using the MAX1800/
MAX1801 when contacting these suppliers.
_______________________________________________________________________________________
5
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