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LT3462A 데이터시트 PDF




Linear에서 제조한 전자 부품 LT3462A은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


PDF 형식의 LT3462A 자료 제공

부품번호 LT3462A 기능
기능 Inverting 1.2MHz/2.7MHz DC/DC Converters
제조업체 Linear
로고 Linear 로고


LT3462A 데이터시트 를 다운로드하여 반도체의 전기적 특성과 매개변수에 대해 알아보세요.




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LT3462A 데이터시트, 핀배열, 회로
LT3462/LT3462A
Inverting 1.2MHz/2.7MHz
DC/DC Converters with
Integrated Schottky in ThinSOT
FEATURES
s Integrated Schottky Rectifier
s Fixed Frequency 1.2MHz/2.7MHz Operation
s Very Low Noise: 1mVP-P Output Ripple
s Low VCESAT Switch: 270mV at 250mA
s –5V at 100mA from 5V Input
s –12V at 30mA from 3.3V Input
s Low Input Bias Current GND Based FB Input
s Low Impedance (40) 1.265V Reference Output
s High Output Voltage: Up to – 38V
s Wide Input Range: 2.5V to 16V
s Uses Tiny Surface Mount Components
s Low Shutdown Current: <10µA
s Low Profile (1mm) SOT-23 (ThinSOTTM) Package
U
APPLICATIO S
s CCD Bias
s LCD Bias
s GaAs FET Bias
s General Purpose Negative Voltage Supply
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation
DESCRIPTIO
The LT®3462/LT3462A are general purpose fixed fre-
quency current mode inverting DC/DC converters. Both
devices feature an integrated Schottky and a low VCESAT
switch allowing a small converter footprint and lower parts
cost. The LT3462 switches at 1.2MHz while the LT3462A
switches at 2.7MHz. These high speeds enable the use of
tiny, low cost and low height capacitors and inductors.
The LT3462/LT3462A operate in a dual inductor inverting
topology that filters both the input and output currents.
Very low output voltage ripple approaching 1mVP-P can be
achieved when ceramic capacitors are used. Fixed fre-
quency switching ensures a clean output free from low
frequency noise typically present with charge pump solu-
tions. The 40V switch allows a VIN to VOUT differential of
up to 38V for dual inductor topologies.
Both devices provide a low impedance 1.265V reference
output to supply the feedback resistor network. A ground
referenced, high impedance FB input allows high feedback
resistor values without compromising output accuracy.
The LT3462/LT3462A are available in a 6-lead SOT-23
package.
TYPICAL APPLICATIO
5V to –5V, 100mA Inverting DC/DC Converter
VIN 22µH 1µF 22µH
5V
VOUT
–5V
SW D
267k
22pF
100mA
1µF VIN FB
LT3462A
68.1k
10µF
SDREF
GND
3462 TA01
75
TA = 25°C
70
65
Efficiency
VIN = 5V
VIN = 3.3V
60
55
0
20 40 60 80 100
LOAD CURRENT (mA)
3462 TA01b
3462af
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LT3462A pdf, 반도체, 판매, 대치품
LT3462/LT3462A
BLOCK DIAGRA
FB 3
A1
E AMP
+
SDREF 4
SHUTDOWN
BIAS CURRENT
CANCELLATION
OFF 3µA
ON 180µA
SHUTDOWN
A2
RC COMP
+
CC
ISRC
RAMP
GENERATOR
1.2MHz*
OSCILLATOR
*LT3462A IS 2.7MHz
VIN 6
1.265V
REFERENCE
+
Q2
DRIVER
RQ
S
+
1 SW 5 D
Q1
0.1
DO
LG
2 GND
VOUT
VOUT
R1 (EXTERNAL)
FB
R2 (EXTERNAL)
CS1 (EXTERNAL)
SDREF
CS2 (EXTERNAL)
SDREF
CS1, CS2 OPTIONAL SOFT-START COMPONENTS
3462 F02
Figure 1. Block Diagram
U
OPERATIO
The LT3462 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram in Figure 1. At the start of each oscillator
cycle, the SR latch is set, turning on the power switch Q1.
A voltage proportional to the switch current is added to a
stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator. When this
voltage exceeds the voltage at the output of the EAMP, the
SR latch is reset, turning off the power switch. The level
at the output of the EAMP is simply an amplified version
of the difference between the feedback voltage and GND.
In this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is taken from
the output; if it decreases, less current is taken. One
function not shown in Figure 1 is the current limit. The
switch current is constantly monitored and not allowed to
exceed the nominal value of 400mA. If the switch current
reaches 400mA, the SR latch is reset regardless of the
output state of the PWM comparator. This current limit cell
protects the power switch as well as various external
components connected to the LT3462.
SDREF is a dual function input pin. When driven low it
shuts the part down, reducing quiescent supply current to
less than 10µA. When not driven low, the SDREF pin has an
internal pull-up current that turns the regulator on. Once
the part is enabled, the SDREF pin sources up to
180µA nominally at a fixed voltage of 1.265V through
external resistor R2 to FB. If there is no fault condition
present, FB will regulate to 0V, and VOUT will regulate to
1.265V • (–R1/R2). An optional soft-start circuit uses the
fixed SDREF pull-up current and a capacitor from SDREF
to VOUT to set the dV/dt on VOUT. In shutdown, an FB bias
current cancellation circuit supplies up to 150µA biasing
current to external resistor R1 while VOUT is lower than FB.
This function eliminates R2 loading of SDREF during
shutdown. As a result, supply current in shutdown may
exceed 10µA by the amount of current flowing in R1.
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LT3462A 전자부품, 판매, 대치품
LT3462/LT3462A
TYPICAL APPLICATIO S
VIN
2.7V
TO 4.2V
3.3V to –8V (LT3462A)
L1A
10µH
C2
1µF
L1B
10µH
VOUT
C1
SW D
VIN FB
R1
267k
–8V
C4 35mA
22pF
1µF
LT3462A
R2
C3
42.2k
4.7µF
SDREF
GND
5V to –5V Supply (LT3462A)
VIN
L1
22µH
C2
1µF
L2
22µH
5V
C1
SW D
VIN FB
R1
267k
C4
22pF
1µF
LT3462A
R2
68.1k
SDREF
GND
C1: TAIYO YUDEN JMK107BJ105MA
C2: TAIYO YUDEN EMK212BJ105MA
C3: TAIYO YUDEN LMK316BJ475
..
L1: WURTH 50310057-100
3462 TA04a
C1: TAIYO YUDEN JMK107BJ105MA
C2: TAIYO YUDEN EMK212BJ105MA
C3: MURATA GRM219R60J106KE19B
L1, L2: MURATA LQH32CN220
Switching Waveform
VOUT
–5V
100mA
C3
10µF
3462 TA05a
INDUCTOR
50mA/DIV
VSW
10V/DIV
VOUT
1mV/DIV
AC COUPLED
200ns/DIV
3462 TA05b
PACKAGE DESCRIPTIO
0.62 0.95
MAX REF
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC
(NOTE 4)
1.22 REF
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC 1.50 – 1.75
(NOTE 4)
PIN ONE ID
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD
FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.20 BSC
DATUM ‘A’
0.95 BSC
0.80 – 0.90
0.09 – 0.20
(NOTE 3)
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
0.01 – 0.10
S6 TSOT-23 0302
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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