Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
MAX1692
Bypass Considerations
Bypass IN and OUT to PGND with 10µF and 47µF,
respectively. Bypass BP and REF to GND with 0.1µF
and 0.22µF, respectively. Locate the bypass capacitors
as close as possible to their respective pins to minimize
noise coupling. For optimum performance, place input
and output capacitors as close to the device as feasi-
ble (see
Capacitor Selection
section).
of which can result in instability or regulation errors.
Connect the inductor, input filter capacitor, and output
filter capacitor as close together as possible, and keep
their traces short, direct, and wide. Connect their
ground pins at a single common node in a star-ground
configuration. The external voltage-feedback network
should be very close to the FB pin, within 0.2in (5mm).
Keep noisy traces, such as from the LX pin, away from
the voltage-feedback network; also keep them sepa-
rate, using grounded copper. Connect GND and PGND
at the highest quality ground. The MAX1692 evaluation
kit manual illustrates an example PC board layout and
routing scheme.
PC Board Layout and Routing
High switching frequencies and large peak currents
make PC board layout a very important part of design.
Good design minimizes excessive EMI on the feedback
paths and voltage gradients in the ground plane, both
Table 1. Suggested Inductors
OUTPUT
VOLTAGE
RANGE
(V)
INDUCTOR L
VALUE
(µH)
SUGGESTED
INDUCTORS
Sumida CD43-100
Coilcraft D01608C-103
Sumida CD54-100
TDK NLC322522-100T
Sumida CD43-220
Sumida CD54-220
Sumida CD43-330
Sumida CD54-330
Table 3. Component Suppliers
COMPANY
AVX
Coilcraft
Coiltronics
Kemet
Nihon
Sanyo
Sprague
Sumida
PHONE
843-946-0238
847-639-6400
561-241-7876
408-986-0424
USA 805- 867-2555
Japan 81-3-3494-7411
USA 619-661-6835
Japan 81-7-2070-6306
603-224-1961
USA 847-956-0666
Japan 81-3-3607-5111
408-573-4150
847-390-4373
FAX
843-626-3123
847-639-1469
561-241-9339
408-986-1442
805- 867-2698
81-3-3494-7414
619-661-1055
81-7-2070-1174
603- 224-1430
847- 956-0702
81-3-3607-5144
408-573-4159
847-390-4428
1.25 to 2.5
10
2.5 to 4.0
4.0 to 5.5
22
33
Table 2. Suggested Capacitors
MANUFACTURER
PART NUMBER
AVX
TPSD476M016R0150
Sanyo
6TPA47M
Sprague
594D686X9010C2T
Taiyo Yuden
JMK325BJ106MN
TYPE
Tantalum
Poscap
Tantalum
Ceramic
ESR
(mΩ)
150
100
95
50
Taiyo Yuden
TDK
10
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