MAX5027 MAXIM [Maxim Integrated Products], MAX5027 Datasheet - Page 11

• Manufacturer Part Number: MAX5027
• Description: 500kHz, 36V Output, SOT23, PWM Step-Up DC-DC Converters
• Manufacturer: MAXIM [Maxim Integrated Products]

trace lengths to reduce stray capacitance, trace resis-
tance, and radiated noise. The trace between the out-
put voltage-divider (MAX5025/MAX5026) and the FB
pin must be kept short, as well as the trace between
GND and PGND.
The shielded drum type inductors have a small air gap
around the top and bottom periphery. The incident fring-
ing magnetic field from this air gap to the copper plane
on the PC board tends to reduce efficiency. This is a
result of the induced eddy currents on the copper plane.
To minimize this effect, avoid laying out any copper
planes under the mounting area of these inductors.
Figure 2. Adjustable 30V Output Circuit
Figure 3. Adjustable 30V Output Circuit with RC Filter
V
CC
V
500kHz, 36V Output, SOT23, PWM Step-Up
CC
______________________________________________________________________________________
= 4.5V TO 11V
= 3V TO 11V
(MAX5025)
(MAX5026)
V
CC
V
CC
= 4.5V TO 11V
= 3V TO 11V
(MAX5025)
(MAX5026)
C1
4.7µF
Inductor Layout
C1
4.7µF
SHDN
V
PGND
CC
MAX5025
MAX5026
47µH
GND
L1
V
SHDN
PGND
CC
MAX5025
MAX5026
TOKO 47µH INDUCTOR
A915BY-470M
47µH
LX
FB
GND
L1
TOKO 47µH INDUCTOR
A915BY-470M
Figures 2 and 3 show the MAX5025/MAX5026 operat-
ing in a 30V boost application. Figure 3 has an RC filter
to reduce noise at the output. These circuits provide
output currents greater than 4mA with an input voltage
of 5V or greater. They are designed by following the
Design Procedure section. Operating characteristics of
these circuits are shown in the Typical Operating
Characteristics section.
____________________Chip Information
TRANSISTOR COUNT: 365
PROCESS: BiCMOS
LX
FB
D1
ZETEX SCHOTTKY DIODE
ZHCS500
D1
R1
147kΩ
R2
6.34kΩ
ZETEX SCHOTTKY DIODE
ZHCS500
DC-DC Converters
R1
147kΩ
R2
6.34kΩ
30V Boost Application Circuit
C2
1µF
100Ω
R3
C2
C2
1µF
1µF
V
+30V
OUT
C3
1µF
V
+30V
OUT
11