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PDF LTC3556 Data sheet ( Hoja de datos )
| Número de pieza | LTC3556 | |
| Descripción | USB Power Manager | |
| Fabricantes | Linear Technology Corporation | |
| Logotipo |  |
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FEATURES
POWER MANAGER
n High Efficiency Switching PowerPathTM Controller
with Bat-TrackTM Adaptive Output Control
n Programmable USB or Wall Current Limit
www.DataSheet(41U0.c0omA/500mA/1A)
n Full Featured Li-Ion/Polymer Battery Charger
n Instant-On Operation with a Discharged Battery
n 1.5A Maximum Charge Current
n Internal 180mΩ Ideal Diode Plus External Ideal Diode
Controller Powers Load in Battery Mode
n Low No-Load IQ when Powered from BAT (<30μA)
DC/DCs
n Dual High Efficiency Buck DC/DCs (400mA/400mA IOUT)
n High Efficiency Buck-Boost DC/DC (1A IOUT)
n All Regulators Operate at 2.25MHz
n Dynamic Voltage Scaling on Two Buck Outputs
n I2C Control of Enables, Mode, Two VOUT Settings
n ENALL Pin with Power-Up Sequence Control
n Low No-Load Quiescent Current: 20μA Each
APPLICATIONS
n HDD-Based MP3 Players, PDAs, GPS, PMPs
n Other USB-Based Handheld Products
Electrical Specifications Subject to Change
LTC3556
High Efficiency USB Power
Manager with Dual Buck
and Buck-Boost DC/DCs
DESCRIPTION
The LTC®3556 is a highly integrated power management
and battery charger IC for Li-Ion/Polymer battery applica-
tions. It includes a high efficiency current limited switching
PowerPath manager with automatic load prioritization, a
battery charger, an ideal diode, and three synchronous
switching regulators (two bucks and one buck-boost).
Designed specifically for USB applications, the LTC3556’s
switching power manager automatically limits input cur-
rent to a maximum of either 100mA or 500mA for USB
applications or 1A for adapter-powered applications.
The LTC3556’s switching input stage transmits nearly all of
the 2.5W available from the USB port to the system load
with minimal power wasted as heat. This feature allows
the LTC3556 to provide more power to the application and
eases the constraint of thermal budgeting in small spaces.
The two buck regulators can provide up to 400mA each
and the buck-boost can deliver 1A.
The LTC3556 is available in the low profile 28-pin (4mm
× 5mm × 0.75mm) QFN surface mount package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PowerPath
and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 6522118 and 6404251.
TYPICAL APPLICATION
High Efficiency PowerPath Manager, Dual Buck, Buck-Boost and LDO
USB/WALL
4.5V TO 5.5V
CHARGE
ENALL
SEQ
3
I2C
USB COMPLIANT
STEP-DOWN
REGULATOR
CC/CV
BATTERY
CHARGER
0V
LTC3556
ALWAYS ON LDO
DUAL HIGH EFFICIENCY
BUCKS
HIGH EFFICIENCY
BUCK-BOOST
I2C PORT
1
2
3
TO OTHER
LOADS
OPTIONAL
+
T Li-Ion
3.3V/25mA
0.8V TO 3.6V/400mA
0.8V TO 3.6V/400mA
RTC/LOW
POWER LOGIC
MEMORY
CORE
μP
2.5V to 3.3V/1A
PGOODALL
HDD/IO
3556 TA01
Battery Charge Current
vs Battery Voltage
700 BATTERY CHARGE CURRENT
600 EXTRA CURRENT
FOR FASTER CHARGING
500
500mA USB CURRENT LIMIT
400
300
200
VBUS = 5V
100 5X MODE
BATTERY CHARGER PROGRAMMED FOR 1A
0
2.8 3 3.2 3.4 3.6 3.8 4 4.2
BATTERY VOLTAGE (V)
3556 TA01b
3556p
1
1 page  
LTC3556
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VBUS = 5V, VIN1 = VIN2 = VIN3 = VOUT3 = 3.8V, BAT = 3.8V, DVCC = 3.3V,
RPROG = 1k, RCLPROG = 3.01k, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
tHD_DAT(I)
Data Hold Time Input
tSU_DAT
Data Setup Time
tLOW SCL Clock Low Period
tHIGH SCL Clock High Period
tf Clock/Data Fall Time
www.DataShter et4U.com
tSP
Clock/Data Rise Time
Input Spike Suppression Pulse Width
Switching Regulators 1, 2 and 3
CB = Capacitance of One BUS Line (pF)
CB = Capacitance of One BUS Line (pF)
0
100
1.3
0.6
20 + 0.1CB
20 + 0.1CB
ns
ns
μs
μs
300 ns
300 ns
50 ns
VIN1,2,3
VOUTUVLO
Input Supply Voltage
VOUT UVLO—VOUT Falling
VOUT UVLO—VOUT Rising
VIN1,2,3 Connected to VOUT Through Low
Impedance. Switching Regulators are
Disabled in UVLO
2.7 5.5
2.5 2.6
2.8 2.9
V
V
V
fOSC Oscillator Frequency
Switching Regulator 1 (Buck)
l 1.8 2.25 2.7
MHz
IVIN1
ILIM1
IOUT1
Pulse Skip Mode Input Current
Burst Mode® Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
PMOS Switch Current Limit
Available Output Current
IOUT1 = 0μA (Note 6)
IOUT1 = 0μA (Note 6)
IOUT1 = 0μA (Note 6)
IOUT1 = 0μA (Note 6)
IOUT1 = 0μA, FB1 = 0V
Pulse Skip/Burst Mode Operation
Pulse Skip/Burst Mode Operation (Note 9)
Forced Burst Mode Operation (Note 9)
LDO Mode (Note 9)
225 400
35 60
20 35
20 35
1
600 800 1100
400
60
50
μA
μA
μA
μA
μA
mA
mA
mA
mA
VFBHIGH1
VFBLOW1
VLSB1
RP1
RN1
RLDO_CL1
RLDO_OL1
IFB1
D1
Maximum Servo Voltage
Minimum Servo Voltage
VFB1 Servo Voltage Step Size
PMOS RDS(ON)
NMOS RDS(ON)
LDO Mode Closed-Loop ROUT
LDO Mode Open-Loop ROUT
FB1 Input Current
Maximum Duty Cycle
Full Scale (1, 1, 1, 1) (Note 7)
Zero Scale (0, 0, 0, 0) (Note 7)
(Note 8)
VFB1 = 0.85V
l 0.780 0.800 0.820
l 0.405 0.425 0.445
25
0.6
0.7
0.25
2.5
–50 50
l 100
V
V
mV
Ω
Ω
Ω
Ω
nA
%
RSW1
SW1 Pull-Down in Shutdown
Switching Regulator 2 (Buck)
10 kΩ
IVIN2
ILIM2
IOUT2
Pulse Skip Mode Input Current
Burst Mode Input Current
Forced Burst Mode Input Current
LDO Mode Input Current
Shutdown Input Current
PMOS Switch Current Limit
Available Output Current
IOUT2 = 0μA (Note 6)
IOUT2 = 0μA (Note 6)
IOUT2 = 0μA (Note 6)
IOUT2 = 0μA (Note 6)
IOUT2 = 0μA, FB2 = 0V
Pulse Skip/Burst Mode Operation
Pulse Skip/Burst Mode Operation (Note 9)
Forced Burst Mode Operation (Note 9)
LDO Mode (Note 9)
225 400
35 60
20 35
20 35
1
600 800 1100
400
60
50
μA
μA
μA
μA
μA
mA
mA
mA
mA
Burst Mode is a registered trademark of Linear Technology Corporation.
3556p
5
5 Page 
LTC3556
TYPICAL PERFORMANCE CHARACTERISTICS
Switching Regulator 3 Step
Response (0mA to 300mA)
VOUT3
100mV/DIV
AC
COUPLED
VIN3 = 3.8V
VOUT3 = 3.3V
Start-Up Sequencing with SEQ = 0V
VIN1 = VIN2 = VIN3 = 4.2V
All Outputs Loaded with 5mA
ENALL
www.DataSheet4U.com
300mA
IOUT3
200mA/
DIV 0
100μs/DIV
3556 G35
1V/DIV
200μs/DIV
VOUT3 = 3.3V
VOUT2 = 1.8V
VOUT1 = 1.6V
3556 G36
PIN FUNCTIONS
LDO3V3 (Pin 1): 3.3V LDO Output Pin. This pin provides
a regulated, always-on, 3.3V supply voltage. LDO3V3
gets its power from VOUT. It may be used for light loads
such as a watchdog microprocessor or real time clock.
A 1μF capacitor is required from LDO3V3 to ground. If
the LDO3V3 output is not used it should be disabled by
connecting it to VOUT.
CLPROG (Pin 2): USB Current Limit Program and Moni-
tor Pin. A resistor from CLPROG to ground determines
the upper limit of the current drawn from the VBUS pin.
A fraction of the VBUS current is sent to the CLPROG pin
when the synchronous switch of the PowerPath switching
regulator is on. The switching regulator delivers power until
the CLPROG pin reaches 1.188V. Several VBUS current limit
settings are available via user input which will typically
correspond to the 500mA and 100mA USB specifications.
A multilayer ceramic averaging capacitor or R-C network
is required at CLPROG for filtering.
NTC (Pin 3): Input to the Thermistor Monitoring Circuits.
The NTC pin connects to a battery’s thermistor to deter-
mine if the battery is too hot or too cold to charge. If the
battery’s temperature is out of range, charging is paused
until it re-enters the valid range. A low drift bias resistor
is required from VBUS to NTC and a thermistor is required
from NTC to ground. If the NTC function is not desired,
the NTC pin should be grounded.
SW1 (Pin 4): Power Transmission Pin for (Buck) Switch-
ing Regulator 1.
VIN1 (Pin 5): Power Input for (Buck) Switching Regula-
tor 1. This pin will generally be connected to VOUT. A 1μF
MLCC capacitor is recommended on this pin.
FB1 (Pin 6): Feedback Input for (Buck) Switching Regula-
tor 1. When regulator 1’s control loop is complete, this
pin servos to 1 of 16 possible set-points based on the
commanded value from the I2C serial port. See Table 4.
FB3 (Pin 7): Feedback Input for (Buck-Boost) Switching
Regulator 3. When regulator 3’s control loop is complete,
this pin servos to 1 of 16 possible set-points based on the
commanded value from the I2C serial port. See Table 4.
VC3 (Pin 8): Output of the Error Amplifier and Voltage
Compensation Node for (Buck-Boost) Switching Regula-
tor 3. External Type I or Type III compensation (to FB3)
connects to this pin. See Applications Information section
for selecting buck-boost compensation components.
SWAB3 (Pin 9): Switch Node for (Buck-Boost) Switching
Regulator 3. Connected to internal power switches A and B.
External inductor connects between this node and SWCD3.
DVCC (Pin 10): Logic Supply for the I2C Serial Port.
VIN3 (Pin 11): Power Input for (Buck-Boost) Switching
Regulator 3. This pin will generally be connected to VOUT. A
1μF (min) MLCC capacitor is recommended on this pin.
VOUT3 (Pin 12): Regulated Output Voltage for (Buck-Boost)
Switching Regulator 3.
3556p
11
11 Page | ||
| Páginas | Total 36 Páginas | |
| PDF Descargar | [ Datasheet LTC3556.PDF ] | |
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