Rainbow Electronics MAX1714A - Manual (Page 2)

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 MOS-
FET gate-drive signals while varying the load cur-
rent.
Detailed Description
Jumper Settings
Evaluating Other Output Voltages
The EV kit output is preset to +2.5V. However, the out-
put 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 5k
Ω to 100kΩ range. R1 is then given by:
R1 = R2 [(V OUT / V FB ) - 1]
where V
FB
= 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 fixed-
frequency PWM operation
Off
Connected to
AGND
Normal operation, allows auto-
matic 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
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561-241-9339 561-241-7876 Coiltronics
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803-626-3123 803-946-0690 AVX
FAX PHONE
Central
Semiconductor
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