MAX863EEE Maxim Integrated Products, MAX863EEE Datasheet - Page 13

• Manufacturer Part Number: MAX863EEE
• Description: DC/DC Switching Controllers Dual PFM Step-Up DC/DC Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX863EEE

• Number Of Outputs: 2
• Output Voltage: 3.15 V to 3.45 V
• Input Voltage: 1.5 V to 11 V
• Mounting Style: SMD/SMT
• Package / Case: QSOP-16
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C

Figure 7. Adjustable Output Circuit
Voltage ripple is the sum of contributions associated
with ESR and the capacitor value, as shown below:
To simplify selection, assume that 75% of the ripple
results from ESR and that 25% results from the capaci-
tor value. Voltage ripple as a consequence of ESR is
approximated by:
so:
Estimate input and output capacitor values for a given
voltage ripple as follows:
where V is the input or output voltage, depending on
which capacitor is being calculated.
Choose input capacitors with working voltage ratings
over the maximum input voltage, and output capacitors
with working voltage ratings higher than their respec-
tive outputs.
MAX863
FB1 OR FB2
V
RIPPLE
V
RIPPLE,ESR
R
C
ESR
______________________________________________________________________________________
≅ V
≥
RIPPLE,ESR
≤
V
0.5L x I
RIPPLE,C
R1
R2
≅ R
V
RIPPLE,ESR
I
ESR
PEAK
Dual, High-Efficiency, PFM, Step-Up
2
PEAK
x I
+ V
x V
PEAK
C1
(OPTIONAL)
C2
(OPTIONAL FOR HIGH-
VOLTAGE CIRCUITS)
RIPPLE,C
V
OUT1
OR V
OUT2
C
OUT
Bypass the MAX863 with 0.1µF or higher value ceramic
capacitors placed as close to the V
pins as possible.
DC-DC converter 1 operates with a 3.3V, 5V, or
adjustable output. For a preset output, connect
SENSE1 to OUT1 (Figures 2 and 4a), then set FB1 to
V
an adjustable output, connect a resistor voltage divider
to the FB1 pin (Figure 7). In adjustable output circuits,
connect SENSE1 to GND.
DC-DC converter 2 can be adjusted from very high
voltages down to V
ed to the FB2 pin, as shown in Figure 7. Select feed-
back resistor R2 in the 10kΩ to 500kΩ range. R1 is
given by:
where 1.25V is the voltage of the internal reference.
Table 1. Component Suppliers
DD
Inductors
Coilcraft
Coiltronics
Dale Inductors
Sumida USA
MOSFETs and Diodes
Central Semiconductor
International Rectifier
Motorola
Current-Sense Resistors
Dale/Vishay
IRC
Electrolytic Capacitors
AVX
Sanyo USA
Sprague
Large-Value Ceramic Capacitors
Marcon/United
Chemi-Con
TDK
Vishay/Vitramon
for 3.3V operation or to GND for 5V operation. For
SUPPLIER
Add V
DC-DC Controller
DD
R1 = R2
IN
and REF Bypass Capacitors
using external resistors connect-
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Set the Output Voltage



1.25V
PHONE
V
OUT
−
DD
 1


, REF, and GND
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FAX
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