MAX730 Maxim, MAX730 Datasheet - Page 11

• Manufacturer Part Number: MAX730
• Description: 5V / Step-Down / Current-Mode PWM DC-DC Converters
• Manufacturer: Maxim

Table 2. Component Values and Suppliers
A good layout is essential for clean, stable operation.
The layouts and component placement diagrams given
in Figures 4, 5, 6, and 7 have been successfully tested
over a wide range of operating conditions. Note that the
1µF bypass capacitor (C2) must be positioned as close
to the V+ and GND pins as possible. Also, place the out-
put capacitor as close to the OUT and GND pins as pos-
sible. The traces connecting the input and output filter
capacitors and the catch diode must be short to mini-
mize inductance and capacitance. For this reason, avoid
using sockets, and solder the IC directly to the PC
board. Use an uninterrupted ground plane if possible.
Surface
Mount
Production
Miniature
Through-
Hole
Low-Cost
Through-
Hole
Method
L1 = 33µH to 100µH
Sumida [phone]
CD54-101KC (MAX730AC)
CD105-101KC
(MAX738AC/MAX744AC)
Coiltronics [phone]
CTX100 series
L1 = 33µH to 100µH
Sumida [phone]
RCH654-101K (MAX730A)
RCH895-101K
(MAX738A/MAX744A)
L1 = 100µH
Maxim
MAXL001
100µH iron-power toroid
Renco [phone]
RL1284-100
______________________________________________________________________________________
MAX730AC/MAX738AC/MAX744AC
Inductors
Current-Mode PWM DC-DC Converters
Commercial Temp. Range
Printed Circuit Layouts
C3 = 68µF, 16V
C4 = 100µF, 6.3V
Matsuo [phone]
267 series
Sprague [phone]
595D/293D series
C3 = 150µF, 16V
C4 = 150µF, 16V or
Nichicon [phone]
PL series
Low-ESR electrolytics
C3 = 150µF, 16V
C4 = 390µF, 6.3V
Maxim
MAXC001
150µF, low-ESR
electrolytic
United Chemicon
[phone]
Capacitors
390µF, 6.3V
A simple lowpass pi-filter (Figure 3) can be added to
the output to reduce output ripple to about 5mVp-p.
The cutoff frequency shown is 21kHz. Since the filter
inductor is in series with the circuit output, its resis-
tance should be minimized so the voltage drop across
it is not excessive.
L1 = 33µH
Sumida [phone]
CD54-330N (MAX730AC)
CD105-330N
(MAX738AE/M, MAX744AE/M)
Coiltronics [phone]
CTX50 series
L1 = 33µH
Sumida [phone]
RCH654-330M (MAX730A)
RCH895-330M
(MAX738A/MAX744A)
MAX730AE/M, MAX738AE/M, MAX744AE/M
Inductors
5V, Step-Down,
Wide Temp. Range
Output-Ripple Filtering
C3 = 68µF, 16V
C4 = 100µF, 6.3V
Matsuo [phone]
267 series
Sprague [phone]
595D/293D series
C3 = 150µF, 16V
C4 = 220µF, 10V
Sanyo [phone]
OS-CON series
Low-ESR
organic semiconductor
(Rated from -55°C to +105°C)
Mallory [phone]
THF series
C3 = 100µF, 20V
C4 = 220µF, 10V
(Rated from -55°C to +125°C)
Capacitors
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