LTC3557EUF-1#PBF Linear Technology, LTC3557EUF-1#PBF Datasheet - Page 21

• Manufacturer Part Number: LTC3557EUF-1#PBF
• Description: IC USB POWER MANAGE 28-QFN
• Manufacturer: Linear Technology

Specifications of LTC3557EUF-1#PBF

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

External HV Buck Control Through the V
The WALL, ACPR and V
with an external high voltage buck regulator such as the
LT
to the V
shown in Figures 3-5 (consult the factory for a complete
list of approved high voltage buck regulators). When the
WALL pin voltage exceeds 4.3V, V
is enabled and drives the V
LT3505. The V
APPLICATIONS INFORMATION
®
3480, LT3481 or LT3505 to provide power directly
OUT
pin through a power P-channel MOSFET as
C
pin control circuitry is designed so that no
(TRANSIENTS
8V TO 34V
8V TO 38V
TO 60V)
C
HV
HV
pins can be used in conjunction
IN
C
IN
pin of the LT3480, LT3481 or
4.7μF
BUCK CIRCUITRY
4.7μF
BUCK CIRCUITRY
HIGH VOLTAGE
HIGH VOLTAGE
Figure 3. LT3480 Buck Control Using V
Figure 4. LT3481 Buck Control Using V
LT3481
C
LT3480
pin control circuitry
68nF
68nF
C
60.4k
Pin
40.2k
NC
150k
150k
10
4
5
6
10
4
5
7
6
V
RUN/SS
R
GND
V
RUN/SS
R
NC
NC
IN
T
GND
IN
T
LT3481
11
LT3480
11
BOOST
BOOST
BIAS
V
V
SW
C
V
C
V
BD
FB
9
26
SW
C
C
LTC3557-1
BD
FB
9
26
WALL ACPR
LTC3557
LTC3557-1
WALL ACPR
LTC3557
2
3
7
1
8
3
2
3
1
8
3
compensation components are required on the V
The voltage at the V
(BAT + 300mV) or 3.6V as shown in Figures 6 and 7. The
feedback network of the high voltage regulator should be
set to generate an output voltage higher than 4.4V (be sure
to include the output voltage tolerance of the buck regula-
tor). The V
V
once the V
independent of the buck regulator feedback network.
C
0.47μF
25
0.47μF
GATE
25
V
control of the external high voltage buck. Therefore,
GATE
BAT
V
OUT
DFLS240L
BAT
OUT
DFLS240L
C
C
6.8μH
6.8μH
(800kHz Switching)
(800kHz Switching)
23
21
22
23
21
22
C
C
control is enabled, the output voltage is set
control of the LTC3557 overdrives the local
549k
200k
Si2333DS
499k
100k
Si2333DS
LTC3557/LTC3557-1
OUT
22μF
22μF
+
+
pin is regulated to the larger of
Si2333DS
(OPT)
35571 F04
Si2333DS
(OPT)
35571 F03
Li-Ion
UP TO
2A
Li-Ion
UP TO
2A
C
C
OUT
OUT
V
BAT
OUT
V
BAT
OUT
21
C
node.
35571fc