19-1307; Rev 0a; 11/97
MAX1672 Evaluation Kit
_______________General Description
The MAX1672 evaluation kit (EV kit) integrates a step-
up switching converter with a linear-regulator output to
provide step-up/down voltage conversion. It accepts a
1.8V to 11V input and converts it to a 3.3V or 5V output
for currents up to 300mA. The EV kit is optimized for
battery applications where the input varies above and
below the regulated output voltage. It provides ultra-low
quiescent current and high efficiency for maximum bat-
tery life. Another benefit of the low-dropout linear post-
regulator is that it reduces high-frequency ripple.
The MAX1672 EV kit is a fully assembled and tested
surface-mount circuit board. With minimal modification,
it can also be used to evaluate other output voltages.
Additional pads on the board accommodate external
feedback resistors for setting different output voltages.
____________________________Features
o
Step-Up/Down Voltage Conversion
o
1.8V to 11V Input Range
o
3.3V or 5V Selectable Output Voltage
o
Adjustable Output Voltage (1.25V to 5.5V)
o
Load Disconnects from Input in Shutdown
o
Up to 300mA Output Current
o
No External FETs Required
o
0.1µA Typical IC Shutdown Current
o
Low-Battery Comparator
o
16-Pin QSOP Package
(same footprint as 8-pin SO)
o
Surface-Mount Components
o
Fully Assembled and Tested
Evaluates: MAX1672
____________________Component List
DESIGNATION QTY
C1, C2
C3, C5,
C6, C7
C4
2
DESCRIPTION
100µF, 16V, low-ESR tantalum capacitors
AVX TPSE107M016R0100 or
Sprague 593D107X0016E2W
0.1µF ceramic capacitors
10µF, 10V tantalum capacitor
Sprague 595D106X0010A2T
1A, 30V Schottky diode
Motorola MBRS130LT3 or
International Rectifier 10BQ40
10µH inductor
Sumida CD54-100
Not installed
1MΩ, 5% resistor
MAX1672EEE (QSOP-16)
3-pin headers
Shunts
MAX1672 PC board
MAX1672 data sheet
______________Ordering Information
PART
MAX1672EVKIT
TEMP. RANGE
0°C to +70°C
BOARD TYPE
Surface Mount
4
1
______________Component Suppliers
SUPPLIER
AVX
Coilcraft
Coiltronics
Dale-Vishay
International
Rectifier
Motorola
Sprague
Sumida
Vishay/Vitramon
PHONE
(803) 946-0690
(708) 639-6400
(561) 241-7876
(402) 564-3131
(310) 322-3331
(602) 303-5454
(603) 224-1961
(708) 956-0666
(203) 268-6261
FAX
(803) 626-3123
(708) 639-1469
(561) 241-9339
(402) 563-6418
(310) 322-3332
(602) 994-6430
(603) 224-1430
(708) 956-0702
(203) 452-5670
D1
1
L1
R1–R4
R5
U1
JU1–JU4
None
None
None
1
0
1
1
4
4
1
1
Note:
Please indicate that you are using the MAX1672 when
contacting these component suppliers.
________________________________________________________________
Maxim Integrated Products
1
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.
MAX1672 Evaluation Kit
Evaluates: MAX1672
_________________________Quick Start
The MAX1672 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.
1) Connect a +1.8V to +11V supply voltage to the VIN
pad. Connect ground to the GND pad.
2) Connect a voltmeter to the VOUT pad.
3) Verify that all other shunts are across pins 1 and 2 of
jumpers JU1–JU4.
4) Turn on the power supply and verify that the output
voltage is 3.3V. For a 5V output, remove the shunt
from JU1 pins 1 and 2, and place it across pins 2
and 3.
Shutdown Mode
The MAX1672 EV kit features a shutdown mode that
preserves battery life by reducing quiescent current to
less than 1µA max. During shutdown, the reference,
low-battery comparator, and all feedback and control
circuitry are turned off. In shutdown, the output of the
boost converter drops to within a Schottky diode drop
below the input, and the linear-regulator output is
turned off and pulled to 0V.
The 3-pin headers JU3 and JU4 select the shutdown
mode. When ONA = 1 or
ONB
= 0, the MAX1672 is on.
When ONA = 0 and
ONB
= 1, the MAX1672 shuts
down. For normal operation, connect ONA to V+ and
ONB
to GND. Table 3 lists the selectable jumper
options.
_______________Detailed Description
The MAX1672 EV kit integrates a step-up switching
converter with a linear-regulator output to provide step-
up/down voltage conversion. It accepts a 1.8V to 11V
input and converts it to a 3.3V or 5V output for currents
up to 300mA. The MAX1672 combines a linear regula-
tor, boost switching regulator, N-channel power MOS-
FET, P-channel pass element, reference, and low-bat-
tery comparator in a single, space-saving, 16-pin
QSOP package. The EV kit is shipped configured for a
3.3V output.
Table 3. Jumpers JU3 and JU4 Functions
ONA PIN
Connected to GND,
JU4 = 2 and 3
Connected to GND,
JU4 = 2 and 3
Connected to V+,
JU4 = 1 and 2
Connected to V+,
JU4 = 1 and 2
ONB
PIN
Connected to GND,
JU3 = 2 and 3
Connected to V+,
JU3 = 1 and 2
Connected to GND,
JU3 = 2 and 3
Connected to V+,
JU3 = 1 and 2
MAX1672
OUTPUT
MAX1672 enabled,
V
OUT
= 3.3V or 5V
Shutdown mode,
V
OUT
= 0V
MAX1672 enabled,
V
OUT
= 3.3V or 5V
MAX1672 enabled,
V
OUT
= 3.3V or 5V
Jumper Selection
The 3-pin header JU1 selects the output voltage. Table
1 lists the selectable jumper options. The 3-pin header
JU2 selects the current limit. Table 2 lists the selectable
jumper options. The EV kit is shipped configured for
I
LIM
= 0.8A.
Power-Good Output
The MAX1672 has an on-chip comparator for low-bat-
tery detection. If the voltage at the PGI input falls below
1.25V (REF), the open-drain comparator output
PGO
goes high. The PGI input is connected to an external
resistor-divider, R3 and R4, which sets the low-battery
detector threshold.
Refer to the
Low-Battery Detection
section of the
MAX1672 data sheet for instructions on selecting resis-
tors R3 and R4.
Table 1. Jumper JU1 Functions
SHUNT
LOCATION
1&2
2&3
5
3/5 PIN
Connected to V+
Connected to GND
MAX1672
OUTPUT
V
OUT
= 3.3V
V
OUT
= 5V
Other Output Voltages
Table 2. Jumper JU2 Functions
SHUNT
LOCATION
1&2
2&3
ILIM PIN
Connected to V+
Connected to GND
CURRENT
LIMIT
I
LIM
= 0.8A
I
LIM
= 0.5A
The MAX1672 EV kit can also be used to evaluate other
output voltages in the 1.25V to 5.5V range. Simply cut
the PC trace shorting resistor R2 and refer to the
Output Voltage Selection
section in the MAX1672 data
sheet for instructions on selecting feedback resistors
R1 and R2. Place the shunt across pins 2 and 3 of JU1.
2
_______________________________________________________________________________________
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