POWER LOSS (mW)
LTC3523/LTC3523-2
Synchronous 600mA Step-Up
and 400mA Step-Down
DC/DC Converters
FEATURES DESCRIPTION
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Dual High Ef ciency DC/DC Converters:
The LTC 3523/LTC3523-2 combine a 600mA step-up
Step-Up (V = 1.8V to 5.25V, I = 600mA)
DC/DC converter with a 400mA synchronous step-down
OUT SW
Step-Down (V = 0.615V to 5.5V, I = 400mA)
DC/DC converter in a tiny 3mm 3mm package. The
OUT OUT
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1.8V to 5.5V Input Voltage Range
1.2MHz/2.4MHz switching frequencies minimize the
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Up to 94% Ef ciency
solution footprint while maintaining high ef ciency. Both
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Pin Selectable Burst Mode Operation
converters feature soft-start and internal compensation,
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45A Quiescent Current in Burst Mode Operation
simplifying the design.
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1.2MHz (LTC3523) or 2.4MHz (LTC3523-2)
Both the step-up and step-down converters are current
Switching Frequency
mode controlled and utilize an internal synchronous rec-
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Independent Power Good Indicator Outputs
ti er for high ef ciency. The step-up supports 0% duty
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Integrated Soft-Start
cycle operation and the step-down converter supports
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Thermal and Overcurrent Protection
100% duty cycle operation to extend battery run time.
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<3A Quiescent Current in Shutdown
If the MODE pin is held high, both converters automati-
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Small 16-Lead 3mm 3mm 0.75mm QFN Package
cally transition between Burst Mode operation and PWM
operation improving light load ef ciency. Fixed, low noise
1.2MHz/2.4MHz PWM operation is selected when MODE
APPLICATIONS
is grounded.
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Digital Cameras
The LTC3523/LTC3523-2 provide a sub-3A shutdown
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Medical Instruments
mode, overtemperature shutdown and current limit pro-
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Industrial Handhelds
tection on both converters. The LTC3523/LTC3523-2 are
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GPS Navigators
housed in a 16-lead 3mm 3mm 0.75mm QFN package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
LTC3523 Ef ciency and Power
Loss vs Load Current
V
IN
100 1000
1.8V TO 3.2V
+
2-CELL
47F
90
ALKALINE 4.7H
V
OUT2
V V V 80
IN1 IN2 BAT 4.7H
STEP-DOWN
100
EFFICIENCY
SW1 SW2 OUTPUT
70
V
OUT1 1.2V
10pF 511k 10F
STEP-UP
200mA 60
OUTPUT
V FB2
OUT P0WER LOSS
LTC3523
50 10
3.3V
V
634k FB1 MODE 511k
10F IN
200mA
40
PGOOD1 PGOOD2 V = 2.4V
IN
V = 3.3V
OUT1
SHDN1 SHDN2 30
365k
V = 1.2V
OUT2 1
GND1 GND2 GND3
20 f = 1.2MHz
OSC
STEP-UP
10
STEP-DOWN
OFF ON OFF ON 3523 TA01a
0 0.1
0.1 1 10 100 1000
LOAD CURRENT (mA)
3523 TA01b
3523fb
1
EFFICIENCY (%)LTC3523/LTC3523-2
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Note 1)
V , V , V , V Voltages .................... 0.3V to 6V
TOP VIEW
IN1 IN2 BAT OUT
SHDN1, PGOOD1, PGOOD2, FB1 Voltages .. 0.3V to 6V
SHDN2, FB2, MODE Voltages ...... 0.3V to (V + 0.3V)
IN2
16 15 14 13
SW1 Voltage
FB1 1 12 FB2
DC .............................................................. 0.3V to 6V
V 2 11 PGOOD2
IN1
17
Pulse < 100ns .......................................... 0.3V to 7V
PG00D1 3 10 MODE
V 4 9 V
SW2 Voltage Pulse < 100ns ......... 0.3V to (V + 0.3V)
OUT IN2
IN2
5 6 7 8
Operating Temperature Range
(Notes 2, 3) .............................................. 40C to 85C
UD PACKAGE
Storage Temperature Range ................... 65C to 125C
16-LEAD (3mm 3mm) PLASTIC QFNs
T = 125C, = 68C/W
JMAX JA
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3523EUD#PBF LTC3523EUD#TRPBF LCYC 40C to 85C
16-Lead (3mm 3mm) Plastic DFN
LTC3523EUD-2#PBF LTC3523EUD-2#TRPBF LDDR 40C to 85C
16-Lead (3mm 3mm) Plastic DFN
Consult LTC Marketing for parts speci ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based nish parts.
For more information on lead free part marking, go to: