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PDF LTC4020 Data sheet ( Hoja de datos )
| Número de pieza | LTC4020 | |
| Descripción | 55V Buck-Boost Multi-Chemistry Battery Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Features
nn Wide Voltage Range: 4.5V to 55V Input, Up to 55V
Output (60V Absolute Maximums)
nn Synchronous Buck-Boost DC/DC Controller
nn Li-Ion and Lead-Acid Charge Algorithms
nn ±0.5% Float Voltage Accuracy
nn ±5% Charge Current Accuracy
nn Instant-On for Heavily Discharged Batteries
nn Ideal Diode Controller Provides Low Loss
PowerPath When Input Power is Limited
nn Input Voltage Regulation for High Impedance Input
Supplies and Solar Panel Peak Power Operation
nn Onboard Timer for Protection and Termination
nn Bad Battery Detection with Auto-Reset
nn NTC Input for Temperature Qualified Charging
nn Binary Coded Open-Collector Status Pins
nn Low Profile (0.75mm) 38-Pin 5mm × 7mm QFN
Package
Applications
nn Portable Industrial and Medical Equipment
nn Solar-Powered Systems
nn Military Communications Equipment
nn 12V to 24V Embedded Automotive Systems
LTC4020
55V Buck-Boost
Multi-Chemistry
Battery Charger
Description
The LTC®4020 is a high voltage power manager provid-
ing PowerPath™ instant-on operation and high efficiency
battery charging over a wide voltage range. An onboard
buck-boost DC/DC controller operates with battery and/or
system voltages above, below, or equal to the input voltage.
The LTC4020 seamlessly manages power distribution
between battery and converter outputs in response to load
variations, battery charge requirements and input power
supply limitations.
The LTC4020 battery charger can provide a constant-current/
constant-voltage charge algorithm (CC/CV), constant-
current charging (CC), or charging with an optimized 4-step,
3-stagelead-acidbatterychargeprofile. Maximumconverter
and battery charge currents are resistor programmable.
The IC's instant-on operation ensures system load power
even with a fully discharged battery. Additional safety
features include preconditioning for heavily discharged
batteries and an integrated timer for termination and
protection.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 7583113 and 8405362.
Typical Application
Buck-Boost DC/DC Converter Controller with PowerPath Battery Charger Accepts
Inputs from 4.5V to 55V and Produces Output Voltages Up to 55V
RSENSEA
VIN
BUCK-BOOST
DC/DC CONVERTER
PowerPath BATTERY CHARGER
VOUT
RSENSEB
TG2 CSP
LTC4020
BG2 CSN
BGATE
VFB
SENSGND
SENSBOT
BG1
TG1
SENSTOP
SENSVIN
NTC
VFBMAX
RCS
RNTC
5V to 30V 6-Cell Lead-Acid Supply/Charger
M(AapxipmliucamtioPnowCeirrcEufifticoinenPcaygevs3V7I)N
100
VOUT = 14V
EFFICIENCY
95
90
INPUT POWER
85
80
P(LOSS)
75
5 10 15 20
VIN (V)
100
90
80
70
60
50
40
30
20
10
0
25 30
4020 TA01b
4020 TA01a
For more information www.linear.com/LTC4020
4020fd
1
1 page  
LTC4020
E lectrical Characteristics The l denotes the specifications which apply over the specified operating
junction temperature
C(TG1, BG1, TG2, BG2) =
range, otherwise specifications
1000pF, VRNG/SS = 2V.
are
at
TA
=
25°C
(Note
2).
PVIN
=
SENSVIN
=
CSP
=
CSN
=
BAT
=
20V,
SHDN
=
2V,
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
BGATE
BGATE Pull-Down Current
Charging Enabled
15 µA
BGATE Pull-Up Current
BGATE Standby Pull-Down Current
Ideal Diode Pull-Down Current
Ideal Diode Forward Voltage
Charging Disabled; VCSN – VBGATE = 2V
VSHDN = 0V
Charging Disabled; VBAT – VCSN = 0.5V
V10B0ATΩ–SVeCrSieNs; RVCeSsNistMoreasured Through
l5
15
120
500
14 20
µA
µA
µA
mV
TIMER
Timer High Threshold
1.5 V
Timer Low Threshold
1.0 V
C/10 Mode Threshold (Rising)
l 0.4 0.5 0.6
V
C/10 Mode Hysteresis
225 mV
VSTAT(L)
IVFBMIN
IVFB
IVIN_REG
IFBG
RNTC
RFBG
Timer Source/Sink Current
Status Pins Enabled Voltage
Instant-On Feedback Bias Current
Feedback Pin Bias Current
Input Regulation Bias Current
Pin Current (Disabled)
NTC Minimum Disable Resistance
FBG Resistance to SGND
VTIMER = 1.25V
IISSTTAATT11
=
=
1mA;
5mA;
IISSTTAATT22
=
=
1mA
5mA
VSHDN = 0V; VFBG = 55V
IFBG = 1mA
l 8.5
10 11.5
l 0.15 0.4
l 0.75 2.5
10
10
10
10
l 250
400
l 20 50
µA
V
V
nA
nA
nA
nA
kΩ
Ω
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 LTC4020 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC4020E 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
LTC4020I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The junction temperature (TJ) is calculated from
the ambient temperature (TA) and power dissipation (PD) according
to the formula TJ = TA + (PD • θJA). 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 resistance and other environmental factors. This IC includes
overtemperature protection that is intended to protect the device during
momentary overload. Junction temperature will exceed 125°C when
overtemperature protection is active. Continuous operation above the
specified maximum operating junction temperature may impair device
reliability.
Note 3: ICC does not include switching currents. VBST1 = VBST2 = VINTVCC
and VSW1 = VSW2 = 0V for testing.
Note 4: See Typical Performance Characteristics
For more information www.linear.com/LTC4020
4020fd
5
5 Page 
LTC4020
Pin Functions
Using the same resistor values for battery voltage pro-
gramming, or RFB1 = RMIN1 and RFB2 = RMIN2, yields an
instant-on voltage that is 85% of VFLOAT (CC/CV charging)
or VABSORB (lead-acid charging):
VOUT(MIN) = 0.85 • VFLOAT/ABSORB
BAT(Pin20):BatteryVoltageMonitorPin. Thispinservesas
the positive reference for the LTC4020 ideal diode function.
If a system load occurs that is large enough to collapse
the DC/DC converter output while charging is terminated
or disabled, and the battery is disconnected (PowerPath
FET is high impedance), the ideal diode function engages
the PowerPath. This function powers the system load from
the battery, and modulates the PowerPath FET gate such
that the system output voltage is maintained with 14mV
across the PowerPath FET, provided the voltage drop due
to RDS(ON) < 14mV. This allows large loads to be accom-
modated without excessive power dissipation in the body
diode of the PowerPath FET.
BGATE (Pin 21): PowerPath FET Gate Driver Output.
This pin is controls the multiple functions of the Power-
Path FET.
This pin is pulled low during a normal charging cycle,
minimizing the FET series impedance between the DC/
DC converter output and the battery.
The BGATE pin is also forced low when the DC/DC converter
is disabled, maintaining a low impedance connection to
power the system from the battery.
When BGATE is pulled low, CSP BGATE is limited inter-
nally to 9.5V, so if CSP > 9.5V, BGATE is maintained by
an internal clamp at CSP – BGATE = 9.5V. The BGATE
pin must be near ground or at the clamp voltage for C/10
detection to occur.
If the battery voltage is lower than the instant-on threshold
(see VFBMIN), BGATE servos the PowerPath FET imped-
ance such that a voltage drop between the CSN pin and
the BAT pin is created while battery charging continues. If
the VCSN – VBAT voltage exceeds 0.4V, maximum charge
current is reduced to decrease power dissipation in the
PowerPath FET.
When the DC/DC converter is enabled, but the battery
charge cycle has terminated, BGATE is pulled high to
disconnect the battery from the converter output. The
battery is also disconnected in the same manner during
NTC faults. The ideal diode function is active during these
periods, however, so if a system load occurs that is larger
than what the DC/DC converter can accommodate, the
battery can supply the required current, and the BGATE
pin will be servo controlled to force a voltage drop of only
14mV across the PowerPath FET. The ideal diode function
is disabled during bad battery faults.
If a PowerPath FET is not being used, such as with a lead-
acid charging application, connect a 0.1nF capacitor from
BGATE to CSN.
CSN (Pin 22): Battery Charger Current Sense Negative
Input. Connect this pin to the negative terminal of the
battery charge current sense resistor (RCS) through a
100Ω resistor. Connect a filter capacitor between this
pin and the CSP pin for ripple reduction. See Applications
Information section.
The value of the sense resistor is related to the maximum
battery charge current (ICSMAX):
RCS = 0.05/ICSMAX
This pin also serves as the negative reference for the
LTC4020 ideal diode function (see BAT).
CSP (Pin 23): Battery Charger Current Sense Positive
Input. Connect this pin to the positive terminal of the
battery charge current sense resistor (RCS) through a
100Ω resistor. Connect a filter capacitor between this
pin and the CSN pin for ripple reduction. See Applications
Information section.
The value of the sense resistor is related to the maximum
battery charge current (ICSMAX) such that:
RCS = 0.05/ICSMAX
CSOUT (Pin 24): Current Sense Amplifier Output and
Charge Current Monitor. Connect 100pF capacitor to
ground.
For more information www.linear.com/LTC4020
4020fd
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC4020.PDF ] | |
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