Rainbow Electronics MAX1714A User Manual
General Description
The MAX1714A evaluation kit (EV kit) demonstrates
a standard 4A application circuit. This DC-DC converter steps down high-voltage batteries and/or
AC adapters, generating a precision, low-voltage
rail for use as chipset, DRAM, and other low-voltage
supplies. For higher current applications up to 12A,
refer to the MAX1714A data sheet.
The MAX1714A EV kit provides a 2.5V output voltage
from a +5V to +24V battery input range. It delivers up to
4A output current with greater than 90% efficiency while
operating at a 300kHz switching frequency, and has
superior line- and load-transient response.
This EV kit is a fully assembled and tested circuit
board. It also allows evaluation of other output voltages
in the 1.0V to 5.5V range by changing feedback resistors R1 and R2.
Features
♦ +5V to +24V Input Voltage Range
♦ Preset 2.5V Output Voltage
♦ 1.0V to 5.5V Adjustable Output
♦ 4A Output Current
♦ 94% Efficient (V
OUT
= 2.5V, V
BATT
= 7V,
I
LOAD
= 2A)
♦ 300kHz Switching Frequency
♦ No Current-Sense Resistor
♦ Power-Good Output
♦ Low-Profile Components
♦ Fully Assembled and Tested
Evaluates: MAX1714A
MAX1714A Evaluation Kit
________________________________________________________________ Maxim Integrated Products 1
19-1536; Rev 1; 12/99
Component List
PART
MAX1714AEVKIT 0°C to +70°C
TEMP. RANGE IC PACKAGE
20 QSOP
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
Ordering Information
Not installed0
R1, R2,
R3, R8, R9
Dual N-channel MOSFET
Fairchild FDS6982A
1N1A, N1B
2-pin headers2JU1, JU2
DESIGNATION DESCRIPTIONQTY
100kΩ ±5% resistor (0805)1R4
1MΩ ±5% resistors (0805)2R5, R6
200Ω ±5% resistor (0805)1R8
MAX1714AEEP (20-pin QSOP)1U1
Shunt (JU1)1None
MAX1714A PC board1None
MAX1714A data sheet1None
MAX1714A EV kit data sheet1None
100mA, 30V Schottky diode
Central Semiconductor CMPSH-3
1D2
1A, 30V Schottky diode
Nihon EP10QY03 or EC10QS03 or
Motorola MBRS130LT3
1D1
3.3µF, 10V, X5R ceramic cap (1206)
Taiyo Yuden LMK316BJ335ML
1C6
DESIGNATION
4.7µF, 10V, X5R ceramic cap (1206)
Taiyo Yuden LMK316BJ475ML
1C5
0.22µF ceramic capacitor (1206)1C4
0.1µF ceramic capacitor (0805)1C3
330µF, 6.3V, 45mΩ C100M
low-ESR capacitor
Sanyo 6TPB330M or
Kemet T510X337M010AS
1C2
10µF, 25V ceramic capacitor (1812)
Taiyo Yuden TMK432BJ106KM or
Tokin C34Y5U1E106Z
1C1
DESCRIPTIONQTY
2200pF ceramic capacitor (0805)1C7
20Ω ±5% resistor (0805)1R7
4.7µH power inductor
Sumida CDRH124-4R7MC (shielded),
Coiltronics UP2B-4R7 (unshielded)
1L1
Equipment Needed
• +5V to +24V power supply, battery, or notebook AC
adapter
• +5V (at 100mA) DC bias power supply
• Dummy load capable of sinking 4A
• Digital multimeter (DMM)
• 100MHz dual-trace oscilloscope
Quick Reference
1) Ensure that the circuit is connected correctly to the
supplies and dummy load prior to applying any
power.
2) Verify that the shunt is placed across JU1.
3) Turn on battery power prior to +5V bias power; oth-
erwise, the output undervoltage protection timer will
time out and the FAULT latch will be set, disabling
the regulator until +5V power is cycled or shutdown
is toggled (refer to the Output Undervoltage
Protection section in the MAX1714A data sheet).
4) Observe the 2.5V output with the DMM and/or oscil-
loscope. Look at the LX switching-node and MOSFET gate-drive signals while varying the load current.
Detailed Description
Jumper Settings
Evaluating Other Output Voltages
The EV kit output is preset to +2.5V. However, the output voltage can also be adjusted between 1.0V and
5.5V by selecting R1 and R2 values. Cut the PC board
trace shorting R2, then select feedback resistor R2 in
the 5kΩ to 100kΩ range. R1 is then given by:
R1 = R2 [(V
OUT
/ VFB) - 1]
where VFB= 1.0V.
If a 3.3V output is desired, cut the trace shorting R2,
then short JU7.
Evaluates: MAX1714A
MAX1714A Evaluation Kit
2 _______________________________________________________________________________________
Table 1. Jumper JU1 Functions
(Shutdown Mode)
SHUNT LOCATION
SHDN PIN
MAX1714A
OUTPUT
On
Connected to
V
CC
MAX1714A
enabled
Off
Connected to
AGND
Shutdown mode,
V
OUT
= 0
SHUNT
LOCATION
SKIP PIN
OPERATIONAL MODE
On
Connected to
V
CC
Low-noise mode, forced fixedfrequency PWM operation
Off
Connected to
AGND
Normal operation, allows automatic PWM/PFM switchover for
pulse skipping at light load,
resulting in highest efficiency
Table 2. Jumper JU2 Functions
(Low-Noise Mode)
Component Suppliers
Note: Please indicate that you are using the MAX1714A when
contacting these component suppliers.
Table 3. Jumper JU3 Functions
(Fixed/Adjustable Current-Limit Selection)
SHUNT
LOCATION
ILIM PIN
CURRENT-LIMIT
THRESHOLD
On Connected to V
CC
100mV (default)
Off
Connected to REF
through voltage-divider
R3/R9. Refer to the
Current-Limit Circuit
section in the MAX1714A
data sheet for information
on selecting R3/R9.
Adjustable from
50mV to 200mV
SUPPLIER
408-434-0375408-432-8020Tokin
408-573-4159408-573-4150Taiyo Yuden
708-956-0702708-956-0666Sumida
619-661-1055619-661-6835Sanyo
847-843-2798847-843-7500Nihon
408-986-1442408-986-0424Kemet
408-721-1635408-721-2181Fairchild
561-241-9339561-241-7876Coiltronics
708-639-1469708-639-6400Coilcraft
516-435-1824516-435-1110
803-626-3123803-946-0690AVX
FAXPHONE
Central
Semiconductor
602-994-6430602-303-5454Motorola
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