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PDF LT8710 Data sheet ( Hoja de datos )
| Número de pieza | LT8710 | |
| Descripción | Synchronous SEPIC/Inverting/Boost Controller | |
| Fabricantes | Linear | |
| Logotipo |  |
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LT8710
Features
Synchronous SEPIC/
Inverting/Boost Controller with
Output Current Control
Description
n Wide Input Range: 4.5V to 80V
n Rail-to-Rail Output Current Monitor and Control
n Input Voltage Regulation for High Impedance Inputs
n C/10 or Power Good Indication Pin
n MODE Pin for Forced CCM or Pulse-Skipping
Operation
n Switching Frequency Up to 750kHz
n Easily Configurable as a Boost, SEPIC, Inverting or
Flyback Converter with Single Feedback Pin
n Can Be Synchronized to External Clock
n High Gain EN/FBIN Pin Accepts Slowly Varying Input
Signals
n 20-Lead TSSOP Package
Applications
n High Power Local Power Supply
n Wide Input Voltage Range SEPIC/Inverting
n Lead Acid Battery Charger
n Automotive Engine Control Unit (ECU) Power
n Solar Panel Power Converter
L, LT, LTC, LTM, 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 7579816.
The LT®8710 is a synchronous PWM DC/DC controller
with a rail-to-rail output current monitor and control. The
LT8710 is ideal for many types of power supply topologies
and can be easily configured for boost, SEPIC, inverting,
or flyback configurations.
The LT8710’s rail-to-rail output current monitor and control
allows the part to be configured in current limited applica-
tions such as battery charging. The FLAG pin can be used
as a power good indication or C/10 indication allowing for
accurate bulk and float battery voltages.
The LT8710’s switching frequency range can be set be-
tween 100kHz and 750kHz using an external resistor or
synchronized to an external clock.
The LT8710 also features innovative EN/FBIN pin cir-
cuitry that allows for slowly varying input signals and
an adjustable undervoltage lockout function. The pin is
also used for input voltage regulation to avoid collapsing
a high impedance input supply. Additional features such
as frequency foldback and soft-start are integrated. The
LT8710 is available in a 20-lead TSSOP package.
Typical Application
300kHz Inverter Generates –5V from a 4.5V to 25V Input
VIN
4.5V TO 25V
+
120µF
2.2µH
13.3k
10k
10µF
2.2µF
×4
118k
10µF ×2
499Ω
2.2µH
VOUT
–5V
7A
330µF
1.5m
BG
VIN
0.47µF
CSN CSP TG
ISN
4m
100µF
×2
EN/FBIN
MODE
LT8710
ISP
BIAS
INTVEE
2.2µF INTVCC 60.4k
INTVCC
RT
SYNC GND
FBX
FLAG
VC
IMON
47nF
SS
220nF
100pF
11.5k
3.3nF
8710 TA01a
For more information www.linear.com/LT8710
Efficiency and Power Loss
100 8
90 7
80 6
70 5
65 4
50 3
40 2
30 VIN = 5V 1
VIN = 12V
20 0
0 12 3 4 5 67
LOAD CURRENT (A)
8710 TA01b
8710f
1
1 page  
LT8710
E lectrical Characteristics The l denotes the specifications which apply over the full operating
temperature range, otherwise
otherwise noted (Note 2).
specifications
for
each
channel
are
at
TA
=
25°C.
VIN
=
12V,
VEN/FBIN
=
12V,
VBIAS
=
12V,
unless
PARAMETER
CONDITIONS
MIN TYP MAX
Gate Drivers, BG and TG
BG Rise Time
BG Fall Time
TG Rise Time
TG Fall Time
BG and TG Non-Overlap Time
BG Minimum On-Time
BG Minimum Off-Time
TG Minimum On-Time
TG Minimum Off-Time
C/10 and Power Good Indicators, FLAG
CBG = 3300pF (Note 3)
CBG = 3300pF (Note 3)
CTG = 3300pF (Note 3)
CTG = 3300pF (Note 3)
TG Rising to BG Rising, CBG = CTG = 3300pF (Note 3)
BG Falling to TG Falling, CBG = CTG = 3300pF (Note 3)
CBG = CTG = 3300pF
CBG = CTG = 3300pF
CBG = CTG = 3300pF
CBG = CTG = 3300pF
24
21
15
16
80 140 220
45 90 150
150 420
100 480
0 150
290 770
FLAG C/10 Indicator Threshold
FLAG C/10 Indicator Hysteresis
VISP – VISN Falling, VFBX = 1.215V
VISP – VISN Rising, VFBX = 1.215V
l1
l4
5 16
10 23
5
FLAG Power Good Threshold for
Positive FBX Voltage
FLAG Power Good Threshold for
Negative FBX Voltage
FLAG Power Good Hysteresis for
Positive or Negative FBX Voltage
VFBX Rising, VISP – VISN = 0V
VFBX Falling, VISP – VISN = 0V
VFBX Falling, VISP – VISN = 0V
VFBX Rising, VISP – VISN = 0V
l 1.127
l 1.062
l 46
l 103
1.153
1.095
68.5
126
58
1.184
1.126
90
152
FLAG Anti-Glitch
Delay from C/10 or Power Good
Threshold Trip to FLAG Toggle
100
FLAG Output Voltage Low
100µA into FLAG Pin
l 9 50
FLAG Leakage Current
VFLAG = 7V, FLAG Off
0.01 1
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
mV
mV
mV
V
V
mV
mV
mV
µs
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 LT8710E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the
–40°C to 125°C operating temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT8710I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 4: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation over the specified maximum operating junction
temperature may impair device reliability.
Note 5: Do not apply a positive or negative voltage or current source to the
BG, TG, and INTVEE pins, otherwise permanent damage may occur.
For more information www.linear.com/LT8710
8710f
5
5 Page 
STATE Diagram
EN/FBIN < 1.3V (TYP)
OR
VIN AND BIAS < 4.5V (MAX)
CHIP OFF
• ALL SWITCHES DISABLED
1.3V < EN/FBIN < 1.7V (TYP)
AND
VIN OR BIAS > 4.5V
INITIALIZE
• SS PULLED LOW
• INTVCC CHARGES UP
EN/FBIN > 1.7V
AND
VIN OR BIAS > 4.5V
AND
INTVCC > 4V (TYP)
ACTIVE MODE
• SS SLOWLY CHARGES UP
• VC PULLED LOW
BEGIN SWITCHING
• NFET BEGINS SWITCHING
• PFET STARTS SWITCHING
WHEN INTVEE REGULATOR
IS OUT OF UVLO
MODE < 1.175V (TYP)
AND
SS > 1.8V (TYP)
MODE > 1.224V (TYP)
FORCED CCM OPERATION
DCM AT LIGHT LOAD
• BG AND TG SWITCH AT
CONSTANT FREQUENCY
• INDUCTOR CURRENT CAN
REVERSE
• IF ISP-ISN VOLTAGE
GOES BELOW –300mV (TYP),
PFET TURNS OFF SO
INDUCTOR CURRENT
GOES MORE POSITIVE
• PFET TURNS OFF FOR
REMAINDER OF CYCLE IF
ISP-ISN VOLTAGE FALLS
BELOW 2.8mV (TYP)
• FOR VERY LIGHT LOAD,
PART MAY SKIP PULSES
LT8710
RESET
RESET
RESET
RESET DETECTED
• SS DISCHARGES QUICKLY
• SWITCHER DISABLED
SS < 50mV
REGULATION
• VC COMMANDS PEAK
INDUCTOR CURRENT TO
MAINTAIN REGULATION
RESET
INTVEE REGULATOR
IN UVLO
AND
SS > 1.8V (TYP)
OUTPUT CURRENT FOLDBACK
• OUTPUT CURRENT LIMITED
TO 25mV (TYP) AVERAGE
ACROSS THE ISP-ISN PINS
RESET
RESET OVER
• NO RESET CONDITIONS
DETECTED
RESET
REGULATION = OUTPUT VOLTAGE (FBX)
INPUT VOLTAGE (EN/FBIN)
OUTPUT CURRENT (ISP-ISN AND IMON)
RESET = UVLO ON VIN OR BIAS ( < 4.5V (MAX))
UVLO ON INTVCC ( < 4V (TYP))
EN/FBIN < 1.7V (TYP) AT 1ST POWER-UP
EN/FBIN < 1.26V (TYP) AFTER ACTIVE MODE SET
OVERCURRENT (ISP – ISN > 63.6mV AVERAGE (TYP))
OVERTEMPERATURE (TJ > 175°C (TYP))
Figure 2. State Diagram
For more information www.linear.com/LT8710
8710 SD
8710f
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LT8710.PDF ] | |
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