LTC3521
19
3521fb
For more information www.linear.com/LTC3521
Typical applicaTion
Dual Supercapacitor to 3.3V at 200mA, 1.8V at 50mA and 1.2V at
100mA Backup Power Supply
Converter Output Voltages Efficiency vs V
IN
+
PV
IN1
PV
IN2
SW2
SW3
FB2
FB3
V
OUT1
LTC3521
SHDN2
SHDN1
R1
1.0M
R3
137k
R4
68.1k
C1
22µF
C2
10µF
C4
4.7µF
1F
+
1F
L1
4.7µH
L2
4.7µH
V
OUT1
3.3V
200mA
V
OUT2
1.8V
50mA
R5
100k
R6
100k
C3
10µF
L3
4.7µH
V
OUT3
1.2V
100mA
V
IN
1.8V TO 5.5V
R2
221k
3521 TA02a
SHDN3
PWM
SW1A
SW1B
FB1
PGOOD2
PGOOD1
PGOOD3
PGND2GND
ON
OFF
PWM
BURST
PGND1A
PGND1B
V
IN
V
IN
(V)
1.8
EFFICIENCY (%)
76
84
92
2.8 3.8 4.8
100
72
80
88
96
3521 TA02c
V
OUT1
= 3.3V
I
OUT
= 200mA
V
OUT2
= 1.8V
I
OUT
= 50mA
V
OUT3
= 1.2V
I
OUT
= 100mA
50µs/DIV
V
IN
2V/DIV
V
OUT2
2V/DIV
V
OUT3
2V/DIV
V
OUT1
2V/DIV
3521 TA02b
LTC3521
20
3521fb
For more information www.linear.com/LTC3521
package DescripTion
FE Package
20-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663 Rev J)
Exposed Pad Variation CB
UF Package
24-Lead Plastic QFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1697 Rev B)
FE20 (CB) TSSOP REV J 1012
0.09 – 0.20
(.0035 – .0079)
0° – 8°
0.25
REF
RECOMMENDED SOLDER PAD LAYOUT
0.50 – 0.75
(.020 – .030)
4.30 – 4.50*
(.169 – .177)
1 3 4
5
6
7
8 9 10
111214 13
6.40 – 6.60*
(.252 – .260)
3.86
(.152)
2.74
(.108)
20 1918 17 16 15
1.20
(.047)
MAX
0.05 – 0.15
(.002 – .006)
0.65
(.0256)
BSC
0.195 – 0.30
(.0077 – .0118)
TYP
2
2.74
(.108)
0.45 ±0.05
0.65 BSC
4.50 ±0.10
6.60 ±0.10
1.05 ±0.10
3.86
(.152)
MILLIMETERS
(INCHES)
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.150mm (.006") PER SIDE
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
SEE NOTE 4
4. RECOMMENDED MINIMUM PCB METAL SIZE
FOR EXPOSED PAD ATTACHMENT
6.40
(.252)
BSC
FE Package
20-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663 Rev J)
Exposed Pad Variation CB
4.00 ±0.10
(4 SIDES)
NOTE:
1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-X)—TO BE APPROVED
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE, IF PRESENT
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
PIN 1
TOP MARK
(NOTE 6)
0.40 ±0.10
2423
1
2
BOTTOM VIEW—EXPOSED PAD
2.45 ±0.10
(4-SIDES)
0.75 ±0.05
R = 0.115
TYP
0.25 ±0.05
0.50 BSC
0.200 REF
0.00 – 0.05
(UF24) QFN 0105 REV B
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.70 ±0.05
0.25 ±0.05
0.50 BSC
2.45 ±0.05
(4 SIDES)
3.10 ±0.05
4.50 ±0.05
PACKAGE
OUTLINE
PIN 1 NOTCH
R = 0.20 TYP
OR 0.35 × 45°
CHAMFER
UF Package
24-Lead Plastic QFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1697 Rev B)
LTC3521
21
3521fb
For more information www.linear.com/LTC3521
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
A 11/10 Addition of PGND1A reflected throughout data sheet
Addition of V
IN
to Typical Applications 1, 19, 22
Revised Note 2 3
Changes to Block Diagram 9
Change to Operation Soft-Start section 11, 13
B 08/13 Corrected pin numbers on Block Diagram UF package 9

LTC3521EFE#PBF

Mfr. #:
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Synchronous 1A, Buck-Boost and Dual 400mA Buck Converters
Lifecycle:
New from this manufacturer.
Delivery:
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