|
|
PDF LTC3633 Data sheet ( Hoja de datos )
| Número de pieza | LTC3633 | |
| Descripción | Dual Channel 3A 15V Monolithic Synchronous Step-Down Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3633 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
|
No Preview Available !
FEATURES
n 3.6V to 15V Input Voltage Range
n 3A Output Current per Channel
n Up to 95% Efficiency
n Low Duty Cycle Operation: 5% at 2.25MHz
n Selectable 0°/180° Phase Shift Between Channels
n Adjustable Switching Frequency: 500kHz to 4MHz
n External Frequency Synchronization
n Current Mode Operation for Excellent Line and
Load Transient Response
n 0.6V Reference Allows Low Output Voltages
n User Selectable Burst Mode® Operation or Forced
Continuous Operation
n Output Voltage Tracking and Soft-Start Capability
n Short-Circuit Protected
n Overvoltage Input and Overtemperature Protection
n Low Power 2.5V Linear Regulator Output
n Power Good Status Outputs
n Available in (4mm × 5mm) QFN-28 and 28-Lead
TSSOP Packages
APPLICATIONS
n Distributed Power Systems
n Battery Powered Instruments
n Point of Load Power Supplies
LTC3633www.DataSheet4U.com
Dual Channel 3A, 15V
Monolithic Synchronous
Step-Down Regulator
DESCRIPTION
The LTC®3633 is a high efficiency, dual-channel monolithic
synchronous buck regulator using a controlled on-time,
current mode architecture, with phase lockable switching
frequency. The two channels can run 180° out of phase,
which relaxes the requirements for input and output ca-
pacitance. The operating supply voltage range is from 3.6V
to 15V, making it suitable for dual cell lithium-ion batteries
as well as point of load power supply applications from
a 12V or 5V supply.
The operating frequency is programmable and synchroniz-
able from 500kHz to 4MHz with an external resistor. The
high frequency capability allows the use of small surface
mount inductors and capacitors. The unique constant
frequency/controlled on-time architecture is ideal for
high step-down ratio applications that operate at high
frequency while demanding fast transient response. An
internal phase lock loop servos the on-time of the internal
one-shot timer to match the frequency of the internal clock
or an applied external clock.
The LTC3633 can select between forced continuous mode
and high efficiency Burst Mode operation.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents including 5481178, 5847554, 6580258, 6304066, 6476589,
6774611.
TYPICAL APPLICATION
VIN
3.6V TO 15V
47μF
x2
VOUT2
5V AT 3A
22μF
1.5μH 0.1μF
73.2k
10k
RUN1 VIN2
RUN2
VIN1 INTVCC
ITH1
LTC3633
ITH2
RT
MODE/SYNC
PHMODE
V2P5
TRACKSS2
TRACKSS1
PGOOD2
PGOOD1
BOOST2
BOOST1
SW2
VON2
VFB2 SGND PGND
SW1
VON1
VFB1
2.2μF
0.1μF 1μH
45.3k
10k
VOUT1
3.3V AT 3A
22μF
3633 TA01a
Efficiency vs Load Current
100
Burst Mode
90 OPERATION
80
70
60
50
40
30
20
10
VIN = 12V
0
1 10
VOUT = 5V
VOUT = 3.3V
100 1000 10000
LOAD CURRENT (mA)
3633 TA01b
3633f
1
1 page  
LTC3633www.DataSheet4U.com
TYPICAL PERFORMANCE CHARACTERISTICS
otherwise noted.
Efficiency vs Load Current
Efficiency vs Load Current
Forced Continuous Mode
Burst Mode Operation
Operation
100
VOUT = 1.8V
90
100
VOUT = 1.8V
90
TJ = 25°C, VIN = 12V, fSW = 1MHz, L = 1μH unless
Efficiency vs Load Current
100
Burst Mode
90 OPERATION
80 80
70 70
60 60
50 50
80 FORCED
70 CONTINUOUS
OPERATION
60
50
40 40
40
30
20
10
0
1
VIN = 4V
VIN = 8V
VIN = 12V
10 100 1000
LOAD CURRENT (mA)
10000
30
20
10
0
1
VIN = 4V
VIN = 8V
VIN = 12V
10 100 1000
LOAD CURRENT (mA)
10000
30
20
10
0
1
VOUT = 5V
VOUT = 3.3V
10 100 1000
LOAD CURRENT (mA)
10000
3633 G01
3633 G02
3633 G03
Efficiency vs Load Current
100
90
80
70
60
50
40
30
20
10
0
0.1
VIN = 4V
VIN = 8V
VIN = 12V
VIN = 15V
1 10 100 1000 10000
LOAD CURRENT (mA)
3633 G04
Efficiency vs Input Voltage
Burst Mode Operation
100
95
90
85
80
75
70
65
60
4
ILOAD = 10mA
ILOAD = 100mA
ILOAD = 1A
ILOAD = 3A
6 8 10 12
INPUT VOLTAGE (V)
14 16
3633 G05
Reference Voltage
vs Temperature
0.605
0.603
0.601
0.599
0.597
0.595
–50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
3633 G06
Load Regulation
1.6
Burst Mode OPERATION
FORCED CONTINUOUS
1.2
0.8
0.4
0.0
–0.4
0 0.5 1 1.5 2 2.5 3
ILOAD (A)
3633 G07
Oscillator Frequency
vs Temperature
10
8
6
4
2
0
–2
–4
–6
–8
–10
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3633 G08
Oscillator Internal Set Frequency
vs Temperature
2.6
RT = INTVCC
2.4
2.2
2.0
1.8
1.6
1.4
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3633 G09
3633f
5
5 Page 
LTC3633www.DataSheet4U.com
OPERATION
The LTC3633 is a dual-channel, current mode monolithic
step down regulator capable of providing 3A of output
current from each channel. Its unique controlled on-time
architecture allows extremely low step-down ratios while
maintaining a constant switching frequency. Each channel
is enabled by raising the voltage on the RUN pin above
1.22V nominally.
Main Control Loop
In normal operation, the internal top power MOSFET is
turned on for a fixed interval determined by a fixed one-
shot timer (“ON” signal in Block Diagram). When the top
power MOSFET turns off, the bottom power MOSFET turns
on until the current comparator ICMP trips, thus restarting
the one shot timer and initiating the next cycle. Inductor
current is measured by sensing the voltage drop across
the SW and PGND nodes of the bottom power MOSFET.
The voltage on the ITH pin sets the comparator threshold
corresponding to inductor valley current. The error ampli-
fier EA adjusts this ITH voltage by comparing an internal
0.6V reference to the feedback signal VFB derived from the
output voltage. If the load current increases, it causes a
drop in the feedback voltage relative to the internal refer-
ence. The ITH voltage then rises until the average inductor
current matches that of the load current.
The operating frequency is determined by the value of the
RT resistor, which programs the current for the internal
oscillator. An internal phase-locked loop servos the switch-
ing regulator on-time to track the internal oscillator edge
and force a constant switching frequency. A clock signal
can be applied to the MODE/SYNC pin to synchronize the
switching frequency to an external source. The regulator
defaults to forced continuous operation once the clock
signal is applied.
At light load currents, the inductor current can drop to zero
and become negative. In Burst Mode operation, a current
reversal comparator (IREV) detects the negative inductor
current and shuts off the bottom power MOSFET, result-
ing in discontinuous operation and increased efficiency.
Both power MOSFETs will remain off until the ITH volt-
age rises above the zero current level to initiate another
cycle. During this time, the output capacitor supplies
the load current and the part is placed into a low current
sleep mode. Discontinuous mode operation is disabled
by tying the MODE/SYNC pin to ground, which forces
continuous synchronous operation regardless of output
load current.
“Power Good” Status Output
The PGOOD open-drain output will be pulled low if the
regulator output exits a ±8% window around the regulation
point. This condition is released once regulation within a
±5% window is achieved. To prevent unwanted PGOOD
glitches during transients or dynamic VOUT changes, the
LTC3633 PGOOD falling edge includes a filter time of ap-
proximately 40μs.
VIN Overvoltage Protection
In order to protect the internal power MOSFET devices
against transient voltage spikes, the LTC3633 constantly
monitors each VIN pin for an overvoltage condition. When
VIN rises above 17.5V, the regulator suspends operation
by shutting off both power MOSFETs on the correspond-
ing channel. Once VIN drops below 16.5V, the regulator
immediately resumes normal operation. The regulator
does not execute its soft-start function when exiting an
overvoltage condition.
Out-Of-Phase Operation
Tying the PHMODE pin high sets the SW2 falling edge to
be 180° out of phase with the SW1 falling edge. There is
a significant advantage to running both channels out of
phase. When running the channels in phase, both top-side
MOSFETs are on simultaneously, causing large current
pulses to be drawn from the input capacitor and supply
at the same time.
When running the LTC3633 channels out of phase, the
large current pulses are interleaved, effectively reducing
the amount of time the pulses overlap. Thus, the total
RMS input current is decreased, which both relaxes the
capacitance requirements for the VIN bypass capacitors
and reduces the voltage noise on the supply line.
One potential disadvantage to this configuration occurs
when one channel is operating at 50% duty cycle. In this
situation, switching noise can potentially couple from one
channel to the other, resulting in frequency jitter on one
or both channels. This effect can be mitigated with a well
designed board layout.
3633f
11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet LTC3633.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3630 | 65V 500mA Synchronous Step-Down Converter | Linear Technology |
| LTC3631 | High Voltage 100mA Synchronous Step-Down Converter |  Linear Technology Corporation |
| LTC3632 | High Voltage 20mA Synchronous Step-Down Converte | Linear Technology Corporation |
| LTC3633 | Dual Channel 3A 15V Monolithic Synchronous Step-Down Regulator | 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 |