|
|
PDF LTC3703 Data sheet ( Hoja de datos )
| Número de pieza | LTC3703 | |
| Descripción | 100V Synchronous Switching Regulator Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3703 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
|
No Preview Available !
FEATU.DRaEStaSheet4U.com DESCRIPTSIwO1i0tc0VhinSgynCRceoLhTgnrCoutrn3loa7oltl0ueo3srrs High Voltage Operation: Up to 100V
ws Large 1Ω Gate Drivers
ws No Current Sense Resistor Required
ws Step-Up or Step-Down DC/DC Converter
ms Dual N-Channel MOSFET Synchronous Drive
s Excellent Transient Response and DC Line Regulation
os Programmable Constant Frequency: 100kHz to
.c600kHz
s ±1% Reference Accuracy
s Synchronizable up to 600kHz
Us Selectable Pulse Skip Mode Operation
t4s Low Shutdown Current: 50µA Typ
s Programmable Current Limit
es Undervoltage Lockout
s Programmable Soft-Start
es 16-Pin Narrow SSOP and 28-Pin SSOP Packages
APPLICATIOUS Shs 48V Telecom and Base Station Power Supplies
tas Networking Equipment, Servers
s Automotive and Industrial Control
a, LTC and LT are registered trademarks of Linear Technology Corporation.
The LTC®3703 is a synchronous step-down switching
regulator controller that can directly step-down voltages
from up to 100V, making it ideal for telecom and automo-
tive applications. The LTC3703 drives external N-channel
MOSFETs using a constant frequency (up to 600kHz),
voltage mode architecture. The external component count
has been minimized, providing a compact overall solution
footprint.
A precise internal reference provides 1% DC accuracy. A
high bandwidth error amplifier and patented line feed
forward compensation provide very fast line and load
transient response. Strong 1Ω gate drivers allow the
LTC3703 to drive multiple MOSFETs for higher current
applications. The operating frequency is user program-
mable from 100kHz to 600kHz and can also be synchro-
nized to an external clock for noise-sensitive applications.
Current limit is programmable with an external resistor
and utilizes the voltage drop across the synchronous
MOSFET to eliminate the need for a current sense resistor.
Soft- start is provided by an external capacitor. Pulling the
soft-start pin low shuts down the LTC3703, reducing
supply current to 50µA.
TYPICAL APPLICATIwO .DVCC
9.3V TO 15V
ww et4U.com3300pF
30k
22k
8.06k
1%
15pF
15k
She330Ω
ata1500pF
113k
1%
0.1µF
MODE/SYNC VIN
FSET BOOST
LTC3703
COMP
TG
FB SW
IMAX
VCC
INV DRVCC
RUN/SS
BG
GND BGRTN
+ 22µF
25V
VIN
BAS21 15V TO 100V
0.1µF
+
Si7456DP
22µF
×2
8µH
10Ω
10µF
Si7456DP
MBR1100
220µF +
25V
×2
1µF
VOUT
12V
5A
.D3703 F01
www 1Figure 1. High Efficiency High Voltage Step-Down Converter
Efficiency vs Load Current
100
VIN = 25V
95 VIN = 50V
VIN = 75V
90
85
80
01 2 345
LOAD (A)
3703 F01b
3703f
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LTC3703
Driver Peak Source Current vs
Temperature
3.0
2.8 VCC = 10V
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
3703 G10
Driver Pull-Down RDS(ON) vs
Supply Voltage
1.1
1.0
0.9
0.8
0.7
0.6
6 7 8 9 10 11 12 13 14 15
DRVCC/BOOST VOLTAGE (V)
3703 G13
RUN/SS Pull-Up Current vs
VCC Voltage
6
5
4
3
2
1
0
68
10 12 14 16
VCC VOLTAGE (V)
3703 G16
Driver Pull-Down RDS(ON) vs
Temperature
1.2
VCC = 10V
1.0
0.8
0.6
0.4
0.2
0
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
3703 G11
Rise/Fall Time vs Gate
Capacitance
70
DRVCC, BOOST = 10V
60
RISE
50
40
30
FALL
20
10
0
0 2000 4000 6000 8000 10000
GATE CAPACITANCE (pF)
3703 G14
RUN/SS Sink Current vs
SW Voltage
25
IMAX = 0.3V
20
15
10
5
0
–5
–10
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
|SW| VOLTAGE (V)
3703 G17
Driver Peak Source Current vs
Supply Voltage
3.0
2.5
2.0
1.5
1.0
0.5
0
5 6 7 8 9 10 11 12 13 14 15
DRVCC/BOOST VOLTAGE (V)
3703 G12
RUN/SS Pull-Up Current vs
Temperature
6
5
4
3
2
1
0
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
1573 G06
Max % DC vs RUN/SS Voltage
100
90
80
70
60
50
40
30
20
10
0
–10
0.5
1.0 1.5 2.0 2.5
RUN VOLTAGE (V)
3.0
3703 G18
3703f
5
5 Page 
U
OPERATIO
For maximum protection, the LTC3703 current limit con-
sists of a steady-state limit circuit and an instantaneous
limit circuit. The steady-state limit circuit is a gm amplifier
that pulls a current from the RUN/SS pin proportional to
the difference between the SW and IMAX voltages. This
current begins to discharge the capacitor at RUN/SS,
reducing the duty cycle and controlling the output voltage
until the current regulates at the limit. Depending on the
size of the capacitor, it may take many cycles to discharge
the RUN/SS voltage enough to properly regulate the
output current. This is where the instantaneous limit
circuit comes into play. The instantaneous limit circuit is
a cycle-by-cycle comparator which monitors the bottom
MOSFET’s drain voltage and keeps the top MOSFET from
turning on whenever the drain voltage is 50mV above the
programmed max drain voltage. Thus the cycle-by-cycle
comparator will keep the inductor current under control
until the gm amplifier gains control.
Pulse Skip Mode
The LTC3703 can operate in one of two modes selectable
with the MODE/SYNC pin—Pulse Skip Mode or forced
continuous mode. Pulse Skip Mode is selected when
increased efficiency at light loads is desired. In this mode,
the bottom MOSFET is turned off when inductor current
reverses to minimize the efficiency loss due to reverse
current flow. As the load is decreased (see Figure 6), the
duty cycle is reduced to maintain regulation until its
minimum on-time (~200ns) is reached. When the load
decreases below this point, the LTC3703 begins to skip
LTC3703
cycles to maintain regulation. The frequency drops but
this further improves efficiency by minimizing gate charge
losses. In forced continuous mode, the bottom MOSFET is
always on when the top MOSFET is off, allowing the
inductor current to reverse at low currents. This mode is
less efficient due to resistive losses, but has the advantage
of better transient response at low currents, constant
frequency operation, and the ability to maintain regulation
when sinking current. See Figure 5 for a comparison of the
effect on efficiency at light loads for each mode. The
MODE/SYNC threshold is 0.8V ±7.5%, allowing the MODE/
SYNC to act as a feedback pin for regulating a second
winding. If the feedback voltage drops below 0.8V, the
LTC3703 reverts to continuous operation to maintain
regulation in the secondary supply.
100
90 VIN = 25V
80 VIN = 75V
70
60 VIN = 25V
50
VIN = 75V
40
30
20
10
0
10
FORCED CONTINUOUS
PULSE SKIP MODE
100 1000
LOAD (mA)
10000
3703 F05
Figure 5. Efficiency in Pulse Skip/Forced Continuous Modes
PULSE SKIP MODE
FORCED CONTINUOUS
DECREASING
LOAD
CURRENT
3703 F06
Figure 6. Comparison of Inductor Current Waveforms for Pulse Skip Mode and Forced Continuous Operation
3703f
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC3703.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3700 | Constant Frequency Step-Down DC/DC Controller | Linear Technology |
| LTC3701 | 2-Phase/ Low Input Voltage/ Dual Step-Down DC/DC Controller | Linear Technology |
| LTC3702 | (LTC3000 Series) SEVEN-SEGMENT NUMERIC LED DISPLAY |  LITE-ON Electronics |
| LTC3703 | 100V Synchronous Switching Regulator Controller | Linear Technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |