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MAX770 Evaluation Kit
_______________General Description
The MAX770 evaluation kit (EV kit) provides a regulated
5V output voltage from a 3V input source. It drives loads
up to 1A with greater than 80% conversion efficiency.
This EV kit is a fully assembled and tested surface-
mount circuit board. Additional pads on the bottom of
the board accommodate the external feedback resis-
tors for setting different output voltages.
The MAX770 EV kit comes with a MAX770CSA IC, but
it can also evaluate the 12V-output MAX771 or
15V-output MAX772—simply order a free sample of the
MAX771CSA or MAX772CSA to substitute for the
MAX770CSA.
____________________________Features
o
5V or Adjustable Output Voltage
o
2.7V to 5.5V Input Range
o
Up to 1A Output Current
o
5µA Max Shutdown Current
o
110µA Max Supply Current
o
300kHz Switching Frequency
o
8-Pin SO, Surface-Mount Construction
o
Fully Assembled and Tested
Evaluates: MAX770
______________Ordering Information
PART
MAX770EVKIT-SO
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
Surface Mount
____________________Component List
DESIGNATION
QTY
DESCRIPTION
150µF, 10V low-ESR tantalum
capacitor
Sprague 595D157X0010D7
AVX TPSE227M010R0100
330µF, 10V low-ESR tantalum
capacitor
Sprague 595D337X001047
AVX TPSE337M006R0100
0.1µF, 50V ceramic capacitors
Schottky diode
1N5820 or Nihon NSQ03A02
(BV = 20V, I
MAX
= 3A)
3-pin header
22µH power inductor
Sumida CDR125-220
(I
SAT
= 2.3A, R
SERIES
= 50mΩ)
N-channel FET
Motorola MTD20N03HDL
(BV = 30V, R
DS(ON)
= 40mΩ
@ V
GS
= 5V)
0.075Ω resistor (low inductance)
IRC LR2010-01-R075-F or
Dale WSL-2512-01-R075-F
Open
MAX770CSA (8-pin SO)
Shunt
PC board
MAX770 data sheet
______________Component Suppliers
SUPPLIER
AVX
PHONE
(803) 946-0690
(800) 282-4975
(847) 639-6400
(561) 241-7876
(605) 668-4131
(512) 992-7900
(714) 969-2491
(602) 303-5454
(805) 867-2555
(408) 988-8000
(800) 554-5565
(603) 224-1961
(847) 956-0666
FAX
(803) 626-3123
(847) 639-1469
(561) 241-9339
(605) 665-1627
(512) 992-3377
(714) 960-6492
(602) 994-6430
(805) 867-2698
(408) 970-3950
(603) 224-1430
(847) 956-0702
C1
1
C2
1
Coilcraft
Coiltronics
Dale
IRC
Matsuo
Motorola
Nihon
Siliconix
Sprague
Sumida
C3, C4
D1
J1
L1
2
1
1
1
N1
1
R1
R2, R3
U1
None
None
None
1
0
1
1
1
1
________________________________________________________________
Maxim Integrated Products
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For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX770 Evaluation Kit
Evaluates: MAX770
_________________________Quick Start
The MAX770 EV kit is a fully assembled and tested
surface-mount printed circuit board. Follow these steps
to verify board operation. Do not turn on the power
supply until all connections are completed.
1) Connect a 2.7V to 5.5V supply to the pad marked
V+ The ground connects to the GND pad.
2) Connect a voltmeter and load (if any) to the V
OUT
pad.
3) Place the shunt on J1 across pins 1 and 2, for
normal operation.
4) Turn on the power and verify that the output voltage
is 5.0V.
5) Refer to the sections
Evaluating
the MAX771/772
and
Other Output Voltages
to modify the board for
different output voltages.
Inductor Selection
The 22µH Sumida CDR125-220 inductor that comes
mounted on the EV kit board is a low-resistance, shield-
ed, medium-current inductor. It provides excellent
performance over the line and load ranges of the
MAX770/MAX771/MAX772. Refer to the section
Choosing an Inductor
in the MAX770/MAX771/MAX772
data sheet for instructions on selecting the inductor
value.
Evaluating the MAX771/MAX772
The MAX770 can be replaced by a MAX771 to gener-
ate a 12V output voltage with up to 0.5A output cur-
rent, or by a MAX772 to generate a 15V output volt-
age with up to 0.4A output current.
Besides replacing
the IC, the only other modification required is to
use a low-ESR output capacitor with a voltage rating
of 20V or greater.
_______________Detailed Description
Jumper Selection
The 3-pin header J1 selects shutdown mode. Table 1
lists the selectable jumper options.
Other Output Voltages
The MAX770, MAX771 and MAX772 are preset for 5V,
12V, and 15V output voltages, respectively. However,
their outputs may also be adjusted via an external
voltage divider formed by R2 and R3 (located on the
bottom of the board). The only other modification
required is to cut the trace across R3. The
Output
Voltage Selection
section of the MAX770/MAX771/
MAX772 data sheet gives instructions for calculating R2
and R3 values.
For input or output voltages greater than 10V,
replace the 10V, C1 and C2 with higher voltage
rating capacitors.
Table 1. Jumper J1 Functions
SHUNT
LOCATION
2&3
1&2
SHDN
PIN
Connected to V+
Connected to GND
MAX770
OUTPUT
Shutdown mode,
V
OUT
= V+ - 0.4V
MAX770 enabled,
V
OUT
= 5.0V
2.7V TO 5.5V
V+
C1
150µF
10V
3
2
1
J1
4
5
C3
0.1µF
3
7
1
8
2
6
C4
0.1µF
R1
0.075Ω
C2
330µF
10V
R2
OPEN
L1
22µH
MTD20N03HDL
SHDN
REF
FB
GND
EXT
CS+
N1
D1
NSQ03A02
V
OUT
SHDN
MAX770
V+
AGND
GND
R3
0Ω
(SHORT)
Figure 1. MAX770 EV Kit Schematic Diagram
2
_______________________________________________________________________________________
MAX770 Evaluation Kit
Evaluates: MAX770
Figure 3. MAX770 EV Kit Component Placement Guide—
Solder Side
Figure 2. MAX770 EV Kit Component Placement Guide—
Component Side
Figure 4. MAX770 EV Kit PC Board Layout—Component Side
Figure 5. MAX770 EV Kit PC Board Layout—Solder Side
_______________________________________________________________________________________
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MAX770 Evaluation Kit
Evaluates: MAX770
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.
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_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1997 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.

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