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PDF LT3464 Data sheet ( Hoja de datos )
| Número de pieza | LT3464 | |
| Descripción | Micropower Boost Converter with Integrated Schottky and Output Disconnect in ThinSOT | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT3464 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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Final Electrical Specifications
LT3464
Micropower Boost
Converter with Integrated Schottky
and Output Disconnect in ThinSOT
FEATURES
DESCRIPTIO
January 2003
s Tiny Solution Size
s Low Quiescent Current
• 25µA in Active Mode
• 0.5µA in Shutdown Mode
s Integrated Schottky Diode
s Integrated PNP Output Disconnect with
Short-Circuit Protection
s Internal Reference Override Pin
s 16V at 8mA from 3.6V Input
s 12V at 20mA from 5V Input
s Low VCE(SAT) Switch: 190mV at 80mA
s Input Range: 2.3V to 10V
s High Output Voltage: Up to 34V
s Low Profile (1mm) ThinSOT Package
U
APPLICATIO S
s LCD Bias
s Handheld Computers
s Battery Backup
s Digital Cameras
s Cellular Phones
The LT®3464 is a micropower step-up DC/DC converter
with integrated Schottky diode and output disconnect
packaged in an 8-lead low profile (1mm) ThinSOTTM. The
small package size, high level of integration, and the use
of tiny SMT components yield a solution size of less than
40mm2. The LT3464 has a typical current limit of 115mA
as well as fast switching speed to allow the use of a chip
inductor and small ceramic capacitors. The internal PNP
disconnects the output load from the input during shut-
down, and also provides output short-circuit protection.
An auxiliary reference input allows the user to override the
internal 1.25V feedback reference with any lower value,
allowing full control of the output voltage during opera-
tion. This device features a low 25µA quiescent current,
which is further reduced to less than 1µA in shutdown. A
current limited fixed off-time control scheme conserves
operating current, resulting in high efficiency over a broad
range of operating current. The rugged 36V switch and
output disconnect circuitry allow outputs up to 34V to be
easily generated in a simple boost topology.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technolgy Corporation
TYPICAL APPLICATIO
VIN
2.3V TO 10V
L1
22µH
76
VIN
SW
3
OUT
1
C1 CTRL
1µF
5
LT3464 CAP
8
SHDN
2
FB
C3
0.22µF
VOUT
16V
C2
0.33µF
3.48M
GND 294k
4
3464 TA01a
C1: TAIYO YUDEN LMK107 BJ105MA-T
C2: TAIYO YUDEN GMK212 BJ474MG-T
C3: TAIYO YUDEN GMK212 BJ224MG-T
L1: MURATA LQH32CN220K
90
80
70
60
50
40
30
0.01
Efficiency
VIN = 8.4V
VIN = 4.2V
0.1 1
10
LOAD CURRENT (mA)
100
3634 TA01b
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.
3464i
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
FB Pin Voltage vs
CTRL Pin Voltage
1.50
1.25
1.00
0.75
0.50
0.25
0
0 0.25 0.5 0.75 1.0 1.25 1.5 1.75
CONTROL PIN VOLTAGE (V)
3464 G17
FB and CTRL Pin
Bias Currents
8
7
CTRL PIN
6
5
4
FEEDBACK PIN
3
2
1
0
–50 –25 0 25 50
TEMPERATURE (°C)
75 100
3464 G18
LT3464
FB Pin Hysteresis
12
10
8
6
4
2
0
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
3464 G19
PI FU CTIO S
CTRL (Pin 1): Internal Reference Override Pin. This allows
the FB voltage to be externally set between 0V and 1.25V.
Tie this pin to above 1.5V (VIN for example) to use the
internal 1.25V reference.
VOUT
=
VCTRL
R2
R1
+ 1
when VCTRL is less than 1.25V
FB (Pin 2): Feedback Pin. The LT3464 regulates its feed-
back pin to 1.25V if the internal reference is used or to
VCTRL if the CTRL pin is between 0V and 1.25V. Connect
the feedback resistor divider tap to this pin. Set the output
voltage by selecting R1 and R2.
R2
=
R1
VOUT
VREF
– 1
OUT (Pin 3): PNP Collector. This is the output of the
Output Disconnect circuit. Bypass this pin with at least a
0.1µF capacitor connected to the CAP pin or to ground.
GND (Pin 4): Ground. Tie this pin directly to the ground
plane.
CAP (Pin 5): PNP Emitter and Schottky Cathode. This pin
connects to the output capacitor, and optionally to the
phase-lead capacitor.
SW (Pin 6): Switch Pin and Schottky Anode. This is the
collector of the internal NPN power switch. Minimize the
metal trace area connected to the pin to minimize EMI.
VIN (Pin 7): Input Supply Pin: Bypass this pin with a
capacitor located as close to the device as possible.
SHDN (Pin 8): Shutdown Pin. This pin is used to put the
device in shutdown mode. Tie the pin low to shut down the
LT3464. Tie high for normal operation See the electrical
specifications for the required voltages.
3464i
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5 Page 
LT3464
APPLICATIO S I FOR ATIO
Board Layout Considerations
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To maximize efficiency, switch rise and fall times are made
as short as possible. To prevent electromagnetic interfer-
ence (EMI) problems, proper layout of the high frequency
switching path is essential. The voltage signal of the SW
pin has sharp rising and falling edges. Minimize the length
and area of all traces connected to the SW pin and always
use a ground plane under the switching regulator to
minimize interplane coupling. In addition, the ground
connection for the feedback resistor R1 should be tied
directly to the GND pin and not shared with any other
component, ensuring a clean, noise-free connection. Rec-
ommended component placement is shown in Figure 6.
VOUT
GND
GND
3464 F07
VIAS TO GROUND PLANE
VIA TO CONTROL
VIA TO SHDN
Figure 6. Recommended Layout
3464i
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11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT3464.PDF ] | |
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