LTC3455 Datasheet, PDF (23/24 Pages) Linear Technology – Dual DC/DC Converter with USB Power Manager and Li-Ion Battery Charger

LTC3455
TYPICAL APPLICATIO S
When the load current exceeds what Switcher 2 can
provide, the 3.3V output droops slightly and the LDO
provides the additional current needed. Figure 16 shows
the transient response when the 3.3V output current is
stepped from 0.5A to 1.2A. More output capacitance can
be added to improve the 3.3V transient response during
these high current load steps.
V_OUT2 (3.3V)
100mV/DIV
AC COUPLED
I_OUT2
0.5A/DIV
0.5A TO 1.2A STEP
M1 GATE
2V/DIV
500µs/DIV
3455 F16
Figure 16. Load Current Step (0.5A to 1.2A) for 3.3V Output
PACKAGE DESCRIPTIO
UF Package
24-Lead Plastic QFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1697)
0.70 ±0.05
4.50 ± 0.05
2.45 ± 0.05
3.10 ± 0.05 ^{(4 SIDES)}
PACKAGE OUTLINE
0.25 ±0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
4.00 ± 0.10
(4 SIDES)
PIN 1
TOP MARK
(NOTE 6)
0.75 ± 0.05
2.45 ± 0.10
(4-SIDES)
BOTTOM VIEW—EXPOSED PAD
R = 0.115
TYP
0.23 TYP
(4 SIDES)
23 24
0.38 ± 0.10
1
2
(UF24) QFN 1103
0.200 REF
0.25 ± 0.05
0.00 – 0.05
0.50 BSC
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
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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