MAX866 Maxim, MAX866 Datasheet - Page 10

• Manufacturer Part Number: MAX866
• Description: 3.3V/5V or Adjustable-Output / Single-Cell DC-DC Converters
• Manufacturer: Maxim

3.3V/5V or Adjustable-Output,
Single-Cell DC-DC Converters
An inductor value of 330µH works well in most applica-
tions, supplying loads over 10mA and allowing typical
start-up voltages of 0.8V. The inductor value is not
critical, and the MAX866/MAX867 can operate with val-
ues from 22µH to 1mH. In general, smaller inductor val-
ues supply more output current while larger values start
with lower input voltage. Several inductor suppliers and
part numbers are listed in Tables 1 and 2.
The peak inductor current should not exceed the induc-
tor’s current rating. Since the MAX866/MAX867 current
limit of 0.5A will not be reached in most applications,
the peak coil current (I
For a typical 1-cell alkaline design, V
so:
Table 1. Component Suppliers
10
AVX
Coilcraft
Matsuo
Motorola
Murata-Erie
Nihon
Sanyo
Sumida
TDK
J.W. Miller
Surface Mount
Miniature
Through Hole
PRODUCTION
______________________________________________________________________________________
METHOD
COMPANY
I
I
PK
PK
= (V
= (1.55V x 4.5µs) / 330µH = 21.14mA
IN(max)
See Table 2
Sumida
RCH654-220
PK
USA: [phone]
USA: [phone]
USA: [phone]
USA: [phone]
USA: [phone]
USA: [phone]
Japan: 81-3-3494-7411
USA: [phone]
Japan: 81-7-2070-6306
USA: [phone]
Japan: 81-3-3607-5111
USA: [phone]
USA: [phone]
) is:
x 4.5µs) / L
INDUCTORS
Inductor Selection
PHONE
IN(max)
Matsuo 267 series
Sprague 595D series
AVX TPS series
Sanyo
OS-CON series
low-ESR organic
semiconductor
is 1.55V,
CAPACITORS
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
81-3-3494-7414
[phone]
81-7-2070-1174
[phone]
81-3-3607-5144
[phone]
[phone]
FAX
which is well within the ratings of most surface-mount
coils. Higher efficiency and output current are achieved
with lower inductor resistance, but unfortunately this is
inversely related to physical size. Table 2 indicates
resistance and height for each coil. Some of the small-
est coils have resistances over 10Ω, and will not pro-
vide the same output power or efficiency of a 1Ω coil.
At light loads however (below 5mA), the efficiency dif-
ferences between low- and high-resistance coils may
be only a percent or two. The Typical Operating
Characteristics graphs show efficiency and output cur-
rent plots for 1.5Ω and 2.9Ω, 330µH coils.
A 47µF, 6V, 0.85Ω, surface-mount tantalum (SMT)
output filter capacitor typically provides 15mV output
ripple when stepping up from 0.9V to 1.4V at 10mA.
Smaller capacitors (down to 10µF with higher ESRs) are
acceptable for light loads or in applications that can
Motorola MBR 0530
Nihon EC15QS02L
Motorola 1N5017
RECTIFIERS
Capacitor Selection