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PDF LT8602 Data sheet ( Hoja de datos )
| Número de pieza | LT8602 | |
| Descripción | 42V Quad Monolithic Synchronous Step-Down Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT8602 (archivo pdf) en la parte inferior de esta página. Total 26 Páginas | ||
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Features
n Flexible Power Supply System Providing Four
Outputs with a Wide Input Range
n Two High Voltage Synchronous Buck Regulators:
3V to 42V Input Voltage Range
Output Currents Up to 2.5A and 1.5A
High Efficiency Up to 93%
n Two Low Voltage Synchronous Buck Regulators:
2.6V to 5.5V Input Voltage Range
Output Currents Up to 1.8A and 94% Efficiency
n Resistor Programmable and Synchronizable
250kHz to 2.2MHz Switching Frequency
n Low Ripple Burst Mode® Operation:
30µA IQ at 12VIN
Output Ripple < 15mV
n Programmable Power-On Reset
n Power Good Indicators
n 2-Phase Clock Reduces Input Current Ripple
n Available in Thermally Enhanced 40-Lead QFN
(6mm × 6mm) Package
Applications
n Automotive Systems
n Distributed Supply Regulation
n Industrial Controls and Power Supplies
LT8602
42V Quad Monolithic
Synchronous Step-Down
Regulator
Description
The LT®8602 is a quad channel, current mode, monolithic
buck switching regulator with a programmable power-on
reset. All regulators are synchronized to a single oscillator
with an adjustable frequency from 250kHz to 2.2MHz. The
LT8602 can be configured for micropower Burst Mode
operation or pulse-skipping operation at light load. Mi-
cropower operation results in quiescent current of 30µA
with all four regulators operating in the application below.
The high voltage channels are synchronous buck regula-
tors that operate from an input of 3V to 42V. The output
currents are up to 1.5A (OUT1) and 2.5A (OUT2). The
low voltage channels operate from an input of 2.6V to
5.5V. Internal synchronous power switches provide high
efficiency with output currents up to 1.8A. The LT8602
uses a 2-phase clock with channels 1 and 3 operating 180°
from channels 2 and 4 to reduce input ripple current on
both HV and LV inputs. All channels have cycle-by-cycle
current limit, providing protection against shorted outputs.
Thermal shutdown provides additional protection.
The LT8602 is available in a 40-lead 6mm × 6mm QFN
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
IN
6V TO 42V
VIN BST1
PVIN1 LT8602
PVIN2
EN/UVLO
SW1
FB1
POREN
RST
4 PG1-4
2 RUN3-4
BST2
SW2
FB2
BIAS
OUT2
PVIN3
PVIN4
INTVCC
SW3
FB3
CPOR
2 TRKSS1, 2
SW4
RT FB4
SYNC GND
5V, 3.3V, 1.8V and 1.2V Step-Down Regulators
OUT1
5V, 1.5A
OUT2
3.3V*
OUT3
1.8V, 1.7A
OUT4
1.2V, 1.8A
100
90
80
70
60
50
40
30
20
10
0
0
HV Channel Efficiency,
VIN = 12V, VOUT1 = 5V
2.0
EFFICIENCY
1.8
1.6
1.4
FSW = 1MHz
FSW = 2MHz
1.2
1.0
0.8
0.6
POWER
LOSS
0.4
0.2
0
0.3 0.6 0.9 1.2 1.5
LOAD CURRENT (A)
8602 TA01b
*IOUT2 = 2.5A – IPVIN3 – IPVIN4
8602 TA01a
For more information www.linear.com/LT8602
100
90
80
70
60
50
40
30
20
10
0
0
LV Channel Efficiency,
VOUT3 = 1.8V
1.0
EFFICIENCY
0.9
0.8
0.7
FSW = 1MHz
FSW = 2MHz
0.6
0.5
0.4
0.3
POWER
LOSS
0.2
0.1
0
0.3 0.6 0.9 1.2 1.5 1.8
LOAD CURRENT (A)
8602 TA01c
8602f
1
1 page  
LT8602
Electrical Characteristics The l denotes the specifications which apply over the full operating
temperature range, otherwise
otherwise noted. (Note 2)
specifications
are
at
TA
=
25°C.
VIN
=
PVIN1
=
PVIN2
=
12V,
EN/UVLO
=
3V,
PVIN3
=
PVIN4
=
3.3V
unless
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Channel 4
Operating Voltage
l 2.6
5.5 V
Feedback Voltage
l 790 800 810
mV
FB Voltage Line Regulation
Input Current FB4
VIN = 3V to 42V
l –100
0.002
0.01
100
%/V
nA
SW4 Current Limit
1.8 3.1 3.5
A
SW4 Leakage
SW4 PMOS On Resistance
SW4 NMOS On Resistance
Lower FB4 Power Good Threshold
Upper FB4 Power Good Threshold
PG4 Output Voltage Low
PG4 Leakage Current
PVIN4 = 5.5V
ISW4 = 1A
ISW4 = 1A
Percentage of VFB4
Percentage of VFB4
IPG4 = –100μA
PG4 = 5V, FB4 = 0.8V
0.1 1
150
120
l 89 92 95
l 105 108 111
l 0.1 0.2
l 30
µA
mΩ
mΩ
%
%
V
µA
RUN4 Threshold Voltage
l 0.695 0.72
0.75
V
RUN4 Input Current
RUN4 = 3.3V
l –100
100 nA
Soft-Start Time
1 ms
Minimum Switch-On Time
Minimum Switch-Off Time
PVIN4 UVLO
Power-On Reset
ISW4 = 1A
ISW1 = 1A
70
70
2.35 2.6
ns
ns
V
CPOR Pull-Up Current
CPOR = 0V
2 μA
POR Delay Time
CPOR = 1000pF
31 35.2 39.4
ms
RST Output Voltage Low
RST Pull-Up Current
IRST = –100μA
POR Timed Out, RST = 0V
l
0.1 0.2
V
30 μA
RST Leakage Current
RST = 5V, POREN = 0V
–40 40 nA
POREN Threshold
l 1.15 1.2 1.25
V
POREN Pull-Up Current
POREN = 0V
0.8 1.2 1.6
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 LT8602E is guaranteed to meet performance specifications
from 0°C to 125°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
LT8602I is guaranteed to meet performance specifications from –40°C
to 125°C junction temperature. High junction temperatures degrade
operating lifetimes. Operating lifetime is derated at junction temperatures
above 125°C.
Note 3: This IC includes overtemperature protection that is intended to
protect the device during overload conditions. Junction temperature will
exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
will reduce lifetime.
Note 4: All four channels enabled as shown in the application circuit
details of front page application (using the 1MHz component values) found
in the Typical Application section.
For more information www.linear.com/LT8602
8602f
5
5 Page 
LT8602
Pin Functions
BIAS (Pin 10): Power to the internal 3.3V regulator. Con-
nect to an output ≥3.1V. Decouple to ground with a low
ESR capacitor.
BST1, BST2 (Pins 4, 5): Boost Voltage for HV Channels.
The Boost Voltage provides a drive voltage higher than
PVIN to the gate of the NMOS top switch.
CPOR (Pin 31): Power-On Reset Timer. Connect a capaci-
tor from this pin to ground to program the power-on reset
timer. CPOR has a 2μA pull-up current.
EN/UVLO (Pin 22): Enable/Undervoltage Lockout Input.
The LT8602 is in low power shutdown when this pin is
below 0.5V. A precision threshold at 1.2V enables the
switching regulators. This allows the EN/UVLO pin to be
used as an input undervoltage lockout by connecting to
a resistor divider between VIN and GND. Connect to VIN if
the UVLO function is not needed.
FB1, FB2 (Pins 26, 25): Feedback Input Pins for the High
Voltage Converters. The converters regulate the corre-
sponding feedback pin to the lesser of 1V or the voltage
on the associated TRKSS pin.
FB3, FB4 (Pins 27, 24): Feedback Input Pins for the Low
Voltage Converters. The converters regulate the corre-
sponding feedback pin to 800mV.
GND (Pins 2, 8, 9, 13, 16, 35, 38, 41): Ground. These
pins must be soldered to PCB ground. The exposed pad
(pin 41) must also be soldered to PCB ground.
INTVCC (Pin 28): Internal 3.3V Regulator Bypass. Do not
load the INTVCC pin with external circuitry. Decouple to
ground with a low ESR 4.7μF capacitor.
PG1, PG2 (Pins 1, 11): Power Good Indicators for Chan-
nels 1 and 2. Open drain logic output pulls down until
the corresponding FB pin rises above 0.92V but remains
below 1.08V.
PG3, PG4 (Pins 40, 12): Power Good Indicators for Chan-
nels 3 and 4. Open drain logic output pulls down until the
corresponding FB pin rises above 0.736V but remains
below 0.864V.
POREN (Pin 39): Power On Reset Enable. This is a logic
input that starts the ramp on the POR timing capacitor.
This input has a weak pull-up.
PVIN1, PVIN2 (Pins 37, 14): Input Supply Voltage to HV Chan-
nels 1 and 2, respectively. These pins are independent and
can be powered from different sources if necessary. Bypass
each input with a low ESR capacitor to the adjacent GND pin.
PVIN3, PVIN4 (Pins 34, 17): Input Supply Voltage to low
voltage Channels 3 and 4. These pins are typically connected
to one of the high voltage converter outputs and should
be locally bypassed with a low ESR capacitor. PVIN3 and
PVIN4 are independent and do not need to be connected
to the same supply voltage.
RST (Pin 32): Power-On Reset Output. CMOS output with
weak pull-up, this pin is held low until the POR times out.
RT (Pin 29): Frequency Programming Resistor. Connect
a resistor from this pin to ground to set the internal oscil-
lator frequency.
RUN3, RUN4 (Pins 30, 18): Run Inputs for the low volt-
age converters.
SW1 (Pin 3): Channel 1 Switch Node. This is the output
of the internal power switches for Channel 1.
SW2 (Pins 6, 7): Channel 2 Switch Node. This is the output
of the internal power switches for Channel 2. These pins
must be connected together.
SW3, SW4 (Pins 36, 15): Switch Nodes for low voltage
converters. These are the outputs of the internal power
switches for Channels 3 and 4.
SYNC (Pin 33): Clock Synchronization Input. A digital
input to allow the LT8602 to synchronize its switching
frequency to an external clock. If clock synchronization is
not used, connect this pin to ground to enable low ripple
burst mode or connect high to enable pulse skip operation
of the synchronous converters. Do not allow SYNC to float.
TRKSS1, TRKSS2 (Pins 21, 20): Track/Soft-Start Inputs
for the High Voltage Converters. When this pin is below
1V, the converter regulates the FB pin to the TRKSS volt-
age instead of the internal reference. The TRKSS pin has
a 2.4μA pull-up current. TRKSS may be left floating
VIN (Pin 23): Input Supply Voltage to Internal Functions.
This pin is independent from any PVIN pin and can be
powered from different sources if necessary. VIN must
be above 3V for the part to operate.
For more information www.linear.com/LT8602
8602f
11
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet LT8602.PDF ] | |
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