POWER LOSS (mW)
LT3970 Series
40V, 350mA Step-Down
Regulator with 2.5A
Quiescent Current and
Integrated Diodes
Fea T Descrip T
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Low Ripple Burst Mode Operation The LT 3970 is an adjustable frequency monolithic buck
2.5A I at 12V to 3.3V switching regulator that accepts a wide input voltage
Q IN OUT
Output Ripple < 5mV range up to 40V, and consumes only 2.5A of quiescent
P-P
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Wide Input Voltage Range: 4.2V to 40V Operating current. A high efficiency switch is included on the die
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Adjustable Switching Frequency: 200kHz to 2.2MHz along with the catch diode, boost diode, and the neces-
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Integrated Boost and Catch Diodes sary oscillator, control and logic circuitry. Low ripple Burst
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350mA Output Current Mode operation maintains high efficiency at low output
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Fixed Output Voltages: 3.3V, 3.42V, 5V currents while keeping the output ripple below 5mV in a
1.8A I at 12V typical application. Current mode topology is used for fast
Q IN
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Accurate 1V Enable Pin Threshold transient response and good loop stability. A catch diode
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Low Shutdown Current: I = 0.7A current limit provides protection against shorted outputs
Q
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Internal Sense Limits Catch Diode Current and overvoltage conditions. An enable pin with accurate
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Power Good Flag threshold is available, producing a low shutdown current
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Output Voltage: 1.21V to 25V of 0.7A. A power good flag signals when V reaches
OUT
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Internal Compensation 90% of the programmed output voltage. The LT3970 is
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Small 10-Pin MSOP and (3mm 2mm) DFN Packages available in small 10-pin MSOP and 3mm 2mm DFN
packages.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
a T
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
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Automotive Battery Regulation
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Power for Portable Products
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Industrial Supplies
Typical a T
5V Step-Down Converter Efficiency
90 1000
V = 12V
V IN
IN
6V TO 40V
0.22F
80 100
V BOOST
IN
LT3970
22H
V
OUT
5V
OFF ON EN SW
10
70
350mA
PG BD
22pF 1M
1
60
RT FB
22F
2.2F
GND
316k
226k
50 0.1
3490 TA01a
f = 600kHz
0.01
40
0.01 0.1 1 10 100
LOAD CURRENT (mA)
3970 TA01b
3970fc
1
EFFICIENCY (%)
ion pplica
ions pplica
ion uresLT3970 Series
a Te m aximum r a T (Note 1)
V , EN Voltage .........................................................40V Operating Junction Temperature Range (Note 2)
IN
BOOST Pin Voltage ...................................................55V E-, I-grade .......................................... 40C to 125C
BOOST Pin Above SW Pin .........................................30V H-grade .............................................. 40C to 150C
FB/V , RT Voltage ....................................................6V Storage Temperature Range ................... 65C to 150C
OUT
PG, BD Voltage .........................................................30V Lead Temperature (Soldering, 10 sec)
MS Only ............................................................ 300C
p in c F T
TOP VIEW
TOP VIEW
*FB/V 1 10 RT
OUT
*FB/V 1 10 RT
2 9 OUT
EN PG
EN 2 9 PG
11
3
V 8 BD
IN
V 3 8 BD
IN
GND
GND 4 7 BOOST
GND 4 7 BOOST
GND 5 6 SW
GND 5 6 SW
MS PACKAGE
10-LEAD PLASTIC MSOP
DDB PACKAGE
10-LEAD (3mm 2mm) PLASTIC DFN = 100C/W
JA
= 76C/W
JA
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
*FB for LT3970, V for LT3970-3.3, LT3970-3.42, LT3970-5.
OUT
o r Der i n F T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3970EDDB#PBF LT3970EDDB#TRPBF LFCZ 40C to 125C
10-Lead (3mm 2mm) Plastic DFN
LT3970IDDB#PBF LT3970IDDB#TRPBF LFCZ 10-Lead (3mm 2mm) Plastic DFN 40C to 125C
LT3970EMS#PBF LT3970EMS#TRPBF LTFDB 10-Lead Plastic MSOP 40C to 125C
LT3970IMS#PBF LT3970IMS#TRPBF LTFDB 10-Lead Plastic MSOP 40C to 125C
LT3970HMS#PBF LT3970HMS#TRPBF LTFDB 10-Lead Plastic MSOP 40C to 150C
LT3970EDDB-3.3#PBF LT3970EDDB-3.3#TRPBF LFQH 40C to 125C
10-Lead (3mm 2mm) Plastic DFN
LT3970IDDB-3.3#PBF LT3970IDDB-3.3#TRPBF LFQH 10-Lead (3mm 2mm) Plastic DFN 40C to 125C
LT3970EMS-3.3#PBF LT3970EMS-3.3#TRPBF LTFQG 10-Lead Plastic MSOP 40C to 125C
LT3970IMS-3.3#PBF LT3970IMS-3.3#TRPBF LTFQG 10-Lead Plastic MSOP 40C to 125C
LT3970HMS-3.3#PBF LT3970HMS-3.3#TRPBF LTFQG 10-Lead Plastic MSOP 40C to 150C
LT3970EDDB-3.42#PBF LT3970EDDB-3.42#TRPBF LGGG 40C to 125C
10-Lead (3mm 2mm) Plastic DFN
LT3970EDDB-5#PBF LT3970EDDB-5#TRPBF LFQF 10-Lead (3mm 2mm) Plastic DFN 40C to 125C
LT3970IDDB-5#PBF LT3970IDDB-5#TRPBF LFQF 10-Lead (3mm 2mm) Plastic DFN 40C to 125C
LT3970EMS-5#PBF LT3970EMS-5#TRPBF LTFQD 10-Lead Plastic MSOP 40C to 125C
LT3970IMS-5#PBF LT3970IMS-5#TRPBF LTFQD 10-Lead Plastic MSOP 40C to 125C
LT3970HMS-5#PBF LT3970HMS-5#TRPBF LTFQD 10-Lead Plastic MSOP 40C to 150C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: