MAX669EUB/V-T 데이터 시트보기 (PDF) - Maxim Integrated
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MAX669EUB/V-T Datasheet PDF : 18 Pages
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1.8V to 28V Input, PWM Step-Up
Controllers in µMAX
VIN = 3V to 12V
C1
68µF
L1
20V
4.7µH
C4
1µF
C2
0.1µF
C3
0.22µF
1 LDO
9 VCC
10 SYNC/
SHDN
4 REF
2
FREQ
R4
100k
1%
MAX668
EXT 8
CS+
PGND
6
R1
0.02Ω
7
5
FB
3
GND
N1 D1
MBRS340T3
FDS6680
C5
68µF
20V
C7
220pF
C6
68µF
20V
R2
218k
1%
R3
24.9k
1%
Figure 4. MAX668 High-Voltage Non-Bootstrapped Configuration
VOUT = 12V @ 1A
C8
0.1µF
VIN = 2.7V to 5.5V
1 LDO
C2
1µF
9 VCC
C3
0.22µF
10 SYNC/
SHDN
4 REF
2
FREQ
R4
100k
1%
MAX668
C1
68µF
L1
10V
4.7µH
EXT 8
CS+
PGND
6
R1
0.02Ω
7
5
FB
3
GND
N1 D1
MBRS340T3
FDS6680
C4
68µF
20V
C7
220pF
C5
68µF
20V
R2
218k
1%
R3
24.9k
1%
VOUT = 12V @ 1A
C6
0.1µF
Figure 5. MAX668 Low-Voltage Non-Bootstrapped Configuration
Non-Bootstrapped Operation
With non-bootstrapped operation, the IC is powered
from the input voltage (VIN) or another source, such as
a logic supply. Non-bootstrapped operation (Figure 4)
is recommended (but not required) for input voltages
above 5V, since the EXT amplitude (limited to 5V by
LDO) at this voltage range is no higher than it would be
with bootstrapped operation. Note that non-boot-
strapped operation is required if the output voltage
exceeds 28V, since this level is too high to safely con-
nect to VCC. Also note that only the MAX668 can be
used with non-bootstrapped operation.
If the input voltage does not exceed 5.5V, the on-chip
regulator can be disabled by connecting VCC to LDO
(Figure 5). This eliminates the regulator forward drop
and supplies the maximum gate drive to the external
FET for lowest on-resistance. Disabling the regulator
also reduces the non-bootstrapped minimum input volt-
age from 3V to 2.7V.
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