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PDF LTC3374 Data sheet ( Hoja de datos )
| Número de pieza | LTC3374 | |
| Descripción | 8-Channel Parallelable 1A Buck DC/DCs | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC3374 (archivo pdf) en la parte inferior de esta página. Total 26 Páginas | ||
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Features
n 8-Channel Independent Step-Down DC/DCs
n Master-Slave Configurable for Up to 4A per Output
Rail with a Single Inductor
n Independent VIN Supplies for Each DC/DC
(2.25V to 5.5V)
n All DC/DCs Have 0.8V to VIN Output Range
n Precision Enable Pin Thresholds for Autonomous
Sequencing
n 1MHz to 3MHz Programmable/Synchronizable
Oscillator Frequency (2MHz Default)
n Die Temperature Monitor Output
n Thermally Enhanced 38-Lead QFN (5mm × 7mm)
and TSSOP Packages
Applications
n General Purpose Multichannel Power Supplies
n Industrial/Automotive/Communications
LTC3374
8-Channel Parallelable
1A Buck DC/DCs
Description
The LTC®3374 is a high efficiency multioutput power sup-
ply IC. The DC/DCs consist of eight synchronous buck
converters (1A each) all powered from independent 2.25V
to 5.5V input supplies.
The DC/DCs may be used independently or in parallel to
achieve higher currents of up to 4A per output with a shared
inductor. The common buck switching frequency may be
programmed with an external resistor, synchronized to an
external oscillator, or set to a default internal 2MHz clock.
The operating mode for all DC/DCs may be programmed
via the MODE pin.
To reduce input noise the buck converters are phased in
90° steps. Precision enable pin thresholds provide reli-
able power-up sequencing. The LTC3374 is available in a
compact 38-lead 5mm × 7mm QFN package as well as a
38-lead TSSOP package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Typical Application
8-Channel 1A Multioutput Buck Regulator
2.7V TO 5.5V
VIN1
VCC BUCK1
0.8V TO VIN1
UP TO 1A
LTC3374
MASTER
VIN2
BUCK2
SLAVE
0.8V TO VIN2
UP TO 1A
EN1
EN2
EN3
EN4
EN5 VIN7
EN6 BUCK7
EN7
EN8
PGOOD_ALL
TEMP
MODE
VIN8
BUCK8
MASTER
MASTER
•••
SLAVE
SLAVE
0.8V TO VIN7
UP TO 1A
0.8V TO VIN8
UP TO 1A
SYNC RT
3374 TA01a
100
90
80
70
60
50
40
30
20
10
0
0
Buck Efficiency vs ILOAD
SINGLE BUCK
DUAL BUCK
TRIPLE BUCK
QUAD BUCK
FORCED CONTINUOUS MODE
VIN = 3.3V, VOUT = 1.8V
fOSC = 1MHz, L = 3.3µH
1000
2000
3000
LOAD CURRENT (mA)
4000
3374 TA01b
For more information www.linear.com/LTC3374
3374fa
1
1 page  
LTC3374
Electrical Characteristics The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = VIN1-8 = 3.3V, unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Interface Logic Pins (PBGOOD_ALL, MODE)
IOH
Output High Leakage Current
PGOOD_ALL 5.5V at Pin
VOL Output Low Voltage
PGOOD_ALL 3mA into Pin
VIH Input High Threshold
MODE
VIL Input Low Threshold
MODE
Interface Logic Pins (EN1, EN2, EN3, EN4, EN5, EN6, EN7, EN8)
–1 1
0.1 0.4
l 1.2
l 0.4
µA
V
V
V
VHI_ALLOFF
VEN_HYS
VHI
IEN
Enable Rising Threshold
Enable Falling Hysteresis
Enable Rising Threshold
Enable Pin Leakage Current
All Regulators Disabled
At Least One Regulator Enabled
EN = VCC = VIN = 5.5V
l 400
l 380
–1
730 1200
60
400 420
1
mV
mV
mV
µA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3374 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC3374E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3374I is guaranteed over the –40°C to 125°C operating junction
temperature range and the LTC3374H is guaranteed over the –40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetimes; operating lifetime is derated for junction
temperatures greater than 125°C. Note that the maximum ambient
temperature consistent with these specifications is determined by
specific operating conditions in conjunction with board layout, the rated
package thermal impedance and other environmental factors. The junction
temperature (TJ in °C) is calculated from ambient temperature (TA in °C)
and power dissipation (PD in Watts) according to the formula:
TJ = TA + (PD • θJA)
where θJA (in °C/W) is the package thermal impedance.
Note 3: The LTC3374 includes overtemperature protection which protects
the device during momentary overload conditions. Junction temperatures
will exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
may impair device reliability.
Note 4: Static current, switches not switching. Actual current may be
higher due to gate charge losses at the switching frequency.
Note 5: The current limit features of this part are intended to protect the
IC from short term or intermittent fault conditions. Continuous operation
above the maximum specified pin current rating may result in device
degradation over time.
For more information www.linear.com/LTC3374
3374fa
5
5 Page 
LTC3374
Pin Functions (QFN/TSSOP)
FB1 (Pin 1/Pin 4): Buck Regulator 1 Feedback Pin. Receives
feedback by a resistor divider connected across the output.
VIN1 (Pin 2/Pin 5): Buck Regulator 1 Input Supply. Bypass
to GND with a 10µF or larger ceramic capacitor.
SW1 (Pin 3/Pin 6): Buck Regulator 1 Switch Node. External
inductor connects to this pin.
SW2 (Pin 4/Pin 7): Buck Regulator 2 Switch Node. External
inductor connects to this pin.
VIN2 (Pin 5/Pin 8): Buck Regulator 2 Input Supply. Bypass
to GND with a 10µF or larger ceramic capacitor. May be
driven by an independent supply or must be shorted to VIN1
when buck regulator 2 is combined with buck regulator 1
for higher current.
FB2 (Pin 6/Pin 9): Buck Regulator 2 Feedback Pin. Receives
feedback by a resistor divider connected across the output.
Connecting FB2 to VIN2 combines buck regulator 2 with
buck regulator 1 for higher current. Up to four converters
may be combined in this way.
FB3 (Pin 7/Pin 10): Buck Regulator 3 Feedback Pin.
Receives feedback by a resistor divider connected across
the output. Connecting FB3 to VIN3 combines buck regula-
tor 3 with buck regulator 2 for higher current. Up to four
converters may be combined in this way.
VIN3 (Pin 8/Pin 11): Buck Regulator 3 Input Supply. Bypass
to GND with a 10µF or larger ceramic capacitor. May be
driven by an independent supply or must be shorted to VIN2
when buck regulator 3 is combined with buck regulator 2
for higher current.
SW3 (Pin 9/Pin 12): Buck Regulator 3 Switch Node.
External inductor connects to this pin.
SW4 (Pin 10/Pin 13): Buck Regulator 4 Switch Node.
External inductor connects to this pin.
VIN4 (Pin 11/Pin 14): Buck Regulator 4 Input Supply.
Bypass to GND with a 10µF or larger ceramic capacitor.
May be driven by an independent supply or must be
shorted to VIN3 when buck regulator 4 is combined with
buck regulator 3 for higher current.
FB4 (Pin 12/Pin 15): Buck Regulator 4 Feedback Pin.
Receives feedback by a resistor divider connected across
the output. Connecting FB4 to VIN4 combines buck regula-
tor 4 with buck regulator 3 for higher current. Up to four
converters may be combined in this way.
EN4 (Pin 13/Pin 16): Buck Regulator 4 Enable Input.
Active high.
EN3 (Pin 14/Pin 17): Buck Regulator 3 Enable Input.
Active high.
PGOOD_ALL (Pin 15/Pin 18): PGOOD Status Pin. Open-
drain output. When the regulated output voltage of any
enabled switching regulator is more than 7.5% below its
programmed level, this pin is driven LOW. When all buck
regulators are disabled PGOOD_ALL is driven LOW.
SYNC (Pin 16/Pin 19): Oscillator Synchronization Pin. Driv-
ing SYNC with an external clock signal will synchronize all
switchers to the applied frequency. The slope compensation
is automatically adapted to the external clock frequency.
The absence of an external clock signal will enable the
frequency programmed by the RT pin. SYNC should be
held at ground if not used. Do not float.
RT (Pin 17/Pin 20): Oscillator Frequency Pin. This pin
provides two modes of setting the switching frequency.
Connecting a resistor from RT to ground will set the switch-
ing frequency based on the resistor value. If RT is tied to
VCC the internal 2MHz oscillator will be used. Do not float.
EN6 (Pin 18/Pin 21): Buck Regulator 6 Enable Input.
Active high.
EN5 (Pin 19/Pin 22): Buck Regulator 5 Enable Input.
Active high.
FB5 (Pin 20/Pin 23): Buck Regulator 5 Feedback Pin.
Receives feedback by a resistor divider connected across
the output. Connecting FB5 to VIN5 combines buck regula-
tor 5 with buck regulator 4 for higher current. Up to four
converters may be combined in this way.
For more information www.linear.com/LTC3374
3374fa
11
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet LTC3374.PDF ] | |
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