LT3433 Datasheet, PDF (1/12 Pages) Linear Technology – High Voltage Step-Up/Step-Down DC/DC Converter

FEATURES
s _{Automatic Step-Up and Step-Down Conversion}
s _{Uses a Single Inductor}
s _{Wide 4V to 60V Input Voltage Range}
s _{VOUT from 3.3V to 20V}
s _{Dual Internal 500mA Switches}
s _{100µA No-Load Quiescent Current}
s _{Low Current Shutdown}
s _{±1% Output Voltage Accuracy}
s _{200kHz Operating Frequency}
s _{Boosted Supply Pin to Saturate High Side Switch}
s _{Frequency Foldback Protection}
s _{Current Limit Foldback Protection}
s _{Current Limit Unaffected by Duty Cycle}
s _{16-lead Thermally Enhanced TSSOP Package}
U
APPLICATIO S
s _{12V Automotive Systems}
s _{Wall Adapter Powered Systems}
s _{Battery Power Voltage Buffering}
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
Final Electrical Specifications
LT3433
High Voltage
Step-Up/Step-Down
DC/DC Converter
DESCRIPTION
September 2003
The LT^®3433 is a 200kHz fixed-frequency current mode
switching regulator that provides both step-up and step-
down regulation using a single inductor. The IC operates
over a 4V to 60V input voltage range making it suitable for
use in various wide input voltage range applications such
as automotive electronics that must withstand both load
dump and cold crank conditions.
Internal control circuitry monitors system conditions and
converts from single switch buck operation to dual switch
bridged operation when required, seamlessly changing
between step-down and step-up voltage conversion.
Optional Burst Mode^® operation reduces no-load quies-
cent current to 100µA and maintains high efficiencies with
light loads.
Current limit foldback and frequency foldback help pre-
vent inductor current runaway during start-up. Program-
mable soft-start helps prevent output overshoot at start-up.
The LT3433 is available in a 16-lead thermally enhanced
TSSOP package.
TYPICAL APPLICATIO
4V to 60V to 5V DC/DC Converter
with Burst Mode Operation
B160A
L1
100µH
CoEv DU1352-101M
V_OUT
5V
4V ≤ V_IN ≤ 8.5V: 125mA
8.5V ≤ V_IN ≤ 60V: 350mA
V_IN
4V TO 60V
+
2.2µF
1N4148
B120A
0.1µF
V_BST
SW_L
SW_H PWRGND
LT3433
V_IN
V_OUT
1N4148
1nF100pF
68k
BURST_EN V_BIAS
V_C
SHDN
0.1µF
100k
0.5%
V_FB
305k
0.5%
SGND
SS
0.01µF
47µF
3433 TA01
Maximum Output
Current vs V_IN
500
V_OUT = 5V
BUCK
400
300
200
BRIDGED
100
0
0 10 20 30 40 50 60
V_IN (V)
3433 TA01c
90
80
70
60
50
40
30
20
0.1
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.
Efficiency
V_IN = 13.8V
V_IN = 4V
1
10
100
OUTPUT CURRENT (mA)
1000
3433 TA01b
3433ia
1