LTC3566资料

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FEATURES
APPLICATIONS
DESCRIPTION
Power Manager Plus 1A Buck-Boost Converter The L TC ®3566 is a highly integrated power management and battery charger IC for Li-Ion/Polymer battery applica-tions. It includes a high effi ciency current limited switching PowerPath manager with automatic load prioritization, a battery charger , an ideal diode, and a high effi ciency synchronous buck-boost switching regulator . Designed specifi cally for USB applications, the L TC3566’s switch-ing power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for adapter-powered applications.
The L TC3566’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 L TC3566 to provide more power to the application and eases the constraint of thermal budgeting in small spaces.The synchronous buck-boost DC/DC can provide up to 1A.The LTC3566 is available in a low profile 24-lead 4mm × 4mm QFN surface mount package.
L TC3566 USB Power Manager with 3.3V/1A Buck-Boost
POWER MANAGER ■ High Effi ciency Switching PowerPath TM Controller with Bat-T rack TM Adaptive Output Control
■ Programmable USB or Wall Input Current Limit (100mA/500mA/1A)
■ Full Featured Li-Ion/Polymer Battery Charger ■ “Instant-On” Operation with Discharged Battery ■ 1.5A Maximum Charge Current
■ Internal 180mΩ Ideal Diode Plus External Ideal Diode Controller Powers Load in Battery Mode
■ Low No-Load I Q when Powered from BAT (<30μA)1A BUCK-BOOST DC/DC ■ High Effi ciency (1A I OUT )
■ 2.25MHz Constant Frequency Operation ■ Low No-Load Quiescent Current (~13μA)■ Zero Shutdown Current ■ Pin Control of All Functions
■
HDD Based MP3 Players, PDA, GPS, PMP Products ■ Other USB Based Handheld Products
OUT =
I OUT (A)
0.01
0E F F I C I E N C Y (%)
204060800.11
3566 TA01b
1001030507090Switching Regulator Effi ciency to System Load (P OUT /P BUS )
T YPICAL APPLICATION 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, 6404251.
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ABSOLUTE MAXIMUM RATINGS
V BUS (T ransient) t < 1ms,
Duty Cycle < 1% ......................................–0.3V to 7V V BUS (Static), V IN1, BAT , NTC, CHRG , MODE, I LIM0, I LIM1, EN1, CHRGEN ................................–0.3V to 6V FB1, V C1 ..............–0.3V to Lesser of 6V or (V IN1 + 0.3V)I CLPROG ....................................................................3mA I CHRG ......................................................................50mA I PROG ........................................................................2mA I LDO3V3 ...................................................................30mA I SW , I BAT , I VOUT ............................................................2A I VOUT1, I SWAB1, I SWCD1 .............................................2.5A Operating Temperature Range (Note 2)....–40°C to 85°C Junction Temperature (Note 3) .............................125°C Storage Temperature Range ...................–65°C to 125°C
(Note 1)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Power Path Switching Regulator
V BUS Input Supply Voltage 4.35 5.5
V I BUSLIM
Total Input Current
1x Mode, V OUT = BAT 5x Mode, V OUT = BAT 10x Mode, V OUT = BAT Suspend Mode, V OUT = BAT ●●●●
874368000.31
954608600.3810050010000.50
mA mA mA mA I BUSQ V BUS Quiescent Current
1x Mode, I OUT = 0mA 5x Mode, I OUT = 0mA 10x Mode, I OUT = 0mA Suspend Mode, I OUT = 0mA 715150.044mA mA mA mA h CLPROG (Note 4)Ratio of Measured V BUS Current to CLPROG Program Current
1x Mode 5x Mode 10x Mode Suspend Mode
2241133214011.3
mA/mA mA/mA mA/mA mA/mA
The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T A = 25°C. V BUS = 5V , V BAT = 3.8V , DV CC = 3.3V , R CLPROG = 3.01k, R PROG = 1k,V IN1 = V OUT1 = 3.8V unless otherwise noted.
PIN CONFIGURATION
242322212019
789TOP VIEW UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
1011126
5432
1131415161718LDO3V3CLPROG NTC FB1V C1GND GATE GND
CHRG PROG I LIM1I LIM0
E N 1
C H R G E N
S W
V B U S
V O U T B A T
S W A B 1
M O D E
V I N 1
V O U T 1
S W C D 1
G N D
25
T JMAX = 125°C, θJA = 37°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION
TEMPERATURE RANGE L TC3566EUF#PBF
L TC3566EUF#TRPBF
3566
24-Lead (4mm × 4mm) Plastic QFN
–40°C to 85°C
Consult L TC Marketing for parts specifi ed with wider operating temperature ranges.Consult L TC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear .com/tapeandreel/
ORDER INFORMATION
ELECTRICAL CHARACTERISTICS
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SYMBOL PARAMETER
CONDITIONS MIN
TYP MAX
UNITS I OUT
(PowerPath)
V OUT Current Available Before Loading BAT
1x Mode, BAT = 3.3V 5x Mode, BAT = 3.3V 10x Mode, BAT = 3.3V Suspend Mode 135********.32mA mA mA mA V CLPROG CLPROG Servo Voltage in Current Limit
1x, 5x, 10x Modes Suspend Mode 1.188100
V mV V UVLO_VBUS V BUS Undervoltage Lockout Rising Threshold Falling Threshold 3.95
4.304.00 4.35V V V UVLO_VBUS
-VBAT
V BUS to BAT Differential Undervoltage Lockout Rising Threshold Falling Threshold
20050
mV mV V OUT
V OUT Voltage
1x, 5x, 10x Modes, 0V < BAT < 4.2V, I OUT = 0mA, Battery Charger Off 3.4BAT + 0.3 4.7V USB Suspend Mode, I OUT = 250μA
4.5 4.6 4.7V f OSC
Switching Frequency
●
1.8
2.25 2.7MHz R PMOS_PowerPath PMOS On-Resistance 0.18ΩR NMOS_PowerPath NMOS On-Resistance 0.30
ΩI PEAK_PowerPath Peak Switch Current Limit
1x, 5x Modes 10x Mode
23A A Battery Charger V FLOAT BAT Regulated Output Voltage
●
4.1794.165 4.2004.200 4.2214.235V V I CHG Constant Current Mode Charge Current
R PROG = 5k
98018510222041065223mA mA I BAT
Battery Drain Current
V BUS > V UVLO , Battery Charger Off,I OUT = 0μA
V BUS = 0V, I OUT = 0μA (Ideal Diode Mode)
2
3.527538μA μA V PROG PROG Pin Servo Voltage 1.000
V V PROG_TRIKL PROG Pin Servo Voltage in T rickle Charge
V BAT < V TRIKL
0.100V V C/10C/10 Threshold Voltage at PROG 100mV h PROG Ratio of I BAT to PROG Pin Current 1022
mA/mA
I TRKL T rickle Charge Current BAT < V TRKL 100mA V TRIKL T rickle Charge Threshold Voltage BAT Rising
2.7 2.85
3.0V ΔV TRKL T rickle Charge Hysteresis Voltage 135mV V RECHRG Recharge Battery Threshold Voltage Threshold Voltage Relative to V FLOAT –75–100–125mV t TERM Safety Timer Termination Timer Starts When BAT = V FLOAT 3.345Hour t BADBAT Bad Battery Termination Time BAT < V TRKL 0.420.50.63Hour h C/10End of Charge Indication Current Ratio
(Note 5)0.088
0.10.112mA/mA
V CHRG CHRG Pin Output Low Voltage I CHRG = 5mA 65
100mV I CHRG
CHRG Pin Leakage Current
V CHRG = 5V
1μA
ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T A = 25°C. V BUS = 5V , V BAT = 3.8V , DV CC = 3.3V , R CLPROG = 3.01k, R PROG = 1k,V IN1 = V OUT1 = 3.8V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
The
● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T A = 25°C. V BUS = 5V, V BAT = 3.8V, DV CC = 3.3V, R CLPROG = 3.01k, R PROG = 1k,
V IN1 = V OUT1 = 3.8V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS R ON_CHG Battery Charger Power FET On
Resistance (Between V OUT and BAT)
0.18Ω
T LIM Junction Temperature in Constant
Temperature Mode
110°C NTC
V COLD Cold Temperature Fault Threshold
Voltage Rising Threshold
Hysteresis
75.076.5
1.5
78.0%V BUS
%V BUS
V HOT Hot Temperature Fault Threshold
Voltage Falling Threshold
Hysteresis
33.434.9
1.5
36.4%V BUS
%V BUS
V DIS NTC Disable Threshold Voltage Falling Threshold
Hysteresis 0.7 1.7
50
2.7%V BUS
mV
I NTC NTC Leakage Current V NTC = V BUS = 5V–5050nA Ideal Diode
V FWD Forward Voltage V BUS = 0V, I OUT = 10mA
I OUT = 10mA 2
15
mV
mV
R DROPOUT Internal Diode On-Resistance,
Dropout
V BUS = 0V0.18ΩI MAX_DIODE Internal Diode Current Limit 1.6A Always On 3.3V Supply
V LDO3V3Regulated Output Voltage0mA < I LDO3V3 < 25mA 3.1 3.3 3.5V R CL_LDO3V3Closed-Loop Output Resistance4ΩR OL_LDO3V Dropout Output Resistance23ΩLogic (I LIM0, I LIM1, EN1, CHRGEN, MODE)
V IL Logic Low Input Voltage0.4V V IH Logic High Input Voltage 1.2V I PD1I LIM0, I LIM1, EN1, MODE
Pull-Down Currents
1.6μA
I PD1_CHRGEN CHRGEN Pull-Down Current 1.610μA Buck-Boost Regulator
V IN1Input Supply Voltage 2.7 5.5V
V OUTUVLO V OUT UVLO -V OUT Falling
V OUT UVLO - V OUT Rising V IN1 Connected to V OUT Through
Low Impedance. Switching Regulator
Disabled in UVLO
2.5 2.6
2.8 2.9
V
V
f OSC Oscillator Frequency PWM Mode● 1.8 2.25 2.7MHz
I VIN1Input Current PWM Mode, I OUT1 = 0μA
Burst Mode® Operation, I OUT1 = 0μA
Shutdown 220
13
400
20
1
μA
μA
μA
Burst Mode is a registered trademark of Linear Technology Corporation.
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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 L TC3566E is guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation with statistical process controls.
Note 3: The L TC3566 includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction
ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T A = 25°C. V BUS = 5V , V BAT = 3.8V , DV CC = 3.3V , R CLPROG = 3.01k, R PROG = 1k,V IN1 = V OUT1 = 3.8V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V OUT1(LOW)Minimum Regulated Output Voltage For Burst Mode Operation or Synchronous PWM Operation
2.65 2.75
V V OUT1(HIGH)Maximum Regulated Output Voltage 5.50 5.60V
I LIMF1Forward Current Limit (Switch A)
PWM Mode
●2 2.53A I PEAK1(BURST)Forward Burst Current Limit (Switch A)
Burst Mode Operation ●200275350mA I ZERO1(BURST)Reverse Burst Current Limit (Switch D)
Burst Mode Operation ●
–300
30
mA I MAX1(BURST)Maximum Deliverable Output Current in Burst Mode Operation 2.7V ≤ V IN1 ≤ 5.5V , 2.75V ≤ V OUT ≤ 5.5V (Note 6)50
mA
V FB1Feedback Servo Voltage ●
0.7800.8000.820V I FB1FB1 Input Current V FB1 = 0.8V –50
50
nA R DS(ON)P PMOS R DS(ON)Switches A, D 0.22ΩR DS(ON)N NMOS R DS(ON)Switches B, C 0.17
Ω
I LEAK(P)PMOS Switch Leakage Switches A, D –11μA I LEAK(N)NMOS Switch Leakage Switches B, C
–1
1
μA R VOUT1V OUT1 Pull-Down in Shutdown 10
kΩD BUCK(MAX)Maximum Buck Duty Cycle PWM Mode ●
100
%D BOOST(MAX)Maximum Boost Duty Cycle PWM Mode 75%t SS1
Soft-Start Time
0.5
ms
temperatures will exceed 125°C when overtemperature protection is active. Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability.
Note 4: Total input current is the sum of quiescent current, I VBUSQ , and measured current given by:
V CLPROG /R CLPROG • (h CLPROG + 1)
Note 5: h C/10 is expressed as a fraction of measured full charge current with indicated PROG resistor .Note 6: Guaranteed by design.
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FORWARD VOL TAGE (V)
C U R R E N T (A )
0.6
0.81.0
0.163566 G01
0.4
0.2
0.04
0.08
0.120.20
BATTERY VOL TAGE (V)
2.7
R E S I S T A N C E (Ω)0.150.20
0.25
3.93566 G02
0.10
0.050 3.0
3.3
3.6
4.2
OUTPUT CURRENT (mA)
0O U T P U T V O L T A G E (V )
4.00
4.25
4.50
8003566 G03
3.75
3.50
3.25
200
400
6001000
BATTERY VOL TAGE (V)
2.7
500600700 3.9
3566 G04
400300 3.0
3.3
3.6
4.2
200100
0C H A R G E C U R R E
N T (m A )
BATTERY VOL TAGE (V)
2.7
C H A R G E C U R R E N T (m A )
255075100125150 3.0
3.3 3.6 3.9
3566 G05
4.2
BATTERY VOL TAGE (V)
2.7
B A T T E R Y
C U R R E N T (μA )
15
20
25
3.93566 G06
10
5
0 3.0
3.3
3.6
4.2
OUTPUT CURRENT (A)
0.01
40E F F I C I E N C Y (%)
506070801000.1
1
3566 G07
90V BUS VOL TAGE (V)
0Q U I E S C E N T C U R R E N T (μA )
30
40
50
4
3566 G09
20
10
1
2
35
BATTERY VOL TAGE (V)
2.7
E F F I C I E N C Y (%)
80
90 3.93566 G08
70
60 3.0
3.3
3.6
4.2
100
TYPICAL PERFORMANCE CHARACTERISTICS
Ideal Diode V-I Characteristics
Ideal Diode Resistance vs Battery Voltage
Output Voltage vs Output Current (Battery Charger Disabled)
USB Limited Battery Charge Current vs Battery Voltage
USB Limited Battery Charge Current vs Battery Voltage
Battery Drain Current vs Battery Voltage
PowerPath Switching Regulator Effi ciency vs Output Current
Battery Charging Effi ciency vs Battery Voltage with No External Load (P BAT /P BUS )
V BUS Quiescent Current vs V BUS Voltage (Suspend)
T A = 25°C unless otherwise noted.
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LOAD CURRENT (mA)
O U T P U T V O L T A G E (V )
4.04.5
5.0
0.43566 G10
3.53.0
2.5
0.1
0.2
0.30.5
LOAD CURRENT (mA)
0V B U S C U R R E N T (m A )
0.3
0.4
0.5
0.43566 G11
0.2
0.1
0.1
0.2
0.30.5
LOAD CURRENT (mA)
O U T P U T V O L T A G E (V )
3.0
3.2
203566 G12
2.8
2.6
5
10
1525
3.4
TEMPERATURE (°C)
–400
C H A R G E C U R R E
N T (m A )100200300400
4080120
3566 G13
500600–202060100
TEMPERATURE (°C)
–40
F L O A T V O L T A
G E (V )
4.194.20603566 G14
4.184.17
–15
10
3585
4.21
TEMPERATURE (°C)
–40
O U T P U T V O L T A G E (V )
3.64
3.66
603566 G15
3.62
3.60
–15
10
3585
3.68
TEMPERATURE (°C)
–40
F R E Q U E N C Y (M H z )
2.2
2.4
603566 G16
2.01.8–15
10
3585
2.6
TEMPERATURE (°C)
–40
Q U I E S C E N T C U R
R E N T (m A )
9
12603566 G17
6
3–15
10
3585
15
TEMPERATURE (°C)
–40
Q U I E S C E
N T C U R R E N T (μA )
50
60
603566 G18
40
30–15
10
3585
70
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage
vs Load Current in Suspend
V BUS Current
vs Load Current in Suspend
3.3V LDO Output Voltage vs Load Current, V BUS = 0V
Battery Charge Current vs Temperature
Battery Charger Float Voltage vs Temperature
Low-Battery (Instant-On) Output Voltage vs Temperature
Oscillator Frequency vs Temperature
V BUS Quiescent Current vs Temperature
V BUS Quiescent Current in Suspend vs Temperature
T A = 25°C unless otherwise noted.
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I LOAD (mA)
30E F F I C I E N C Y (%)
90100201080507060400.1
10100
1000
3566 G25
01
V IN1 (V)
2.7E F F I C I E N C Y (%)
6080100 4.33566 G26
4020
507090
30100
3.1 3.5
3.9
4.7
I LOAD (mA)
30E F F I C I E N C Y (%)
90100
2010
80
507060400.1
10100
1000
3566 G27
01
TEMPERATURE (°C)
–550
P M O S R D S (O N ) (Ω)NMOS R DS(ON) (Ω)0.05
0.150.200.25
–15
25451253566 G22
0.10–35565851050.30
0.10
0.15
0.250.300.35
0.200.40
TEMPERATURE (°C)
–552300
I L I M F (m A )
2350
245025002550
–15
25451253566 G23
2400–35565851052600TEMPERATURE (°C)
–55
11.0
I Q (μA )
11.5
12.513.013.5
–15
25451253566 G24
12.0–355658510514.0
CHRG PIN VOL TAGE (V)
0C H R G P I N C U R R E N T (m A )
6080100
43566 G19
40200
1
2
35
I LDO3V35mA/DIV
0mA
20μs/DIV
BAT = 3.8V
3566 G2
V LDO3V320mV/DIV AC COUPLED
TEMPERATURE (°C)
–40
B A T T E R Y
C U R R E N T (μA )
30
40
50
603566 G21
20
10
0–15
10
3585
TYPICAL PERFORMANCE CHARACTERISTICS
CHRG Pin Current vs Voltage (Pull-Down State)
3.3V LDO Step Response (5mA to 15mA)
Battery Drain Current vs Temperature
R DS(ON) for Buck-Boost Regulator Power Switches vs Temperature
Buck-Boost Regulator Current Limit vs Temperature
Buck-Boost Regulator Burst Mode Operation Quiescent Current
Buck-Boost Regulator PWM Mode Effi ciency
Buck-Boost Regulator PWM Effi ciency vs V IN1
Buck-Boost Regulator vs I LOAD
T A = 25°C unless otherwise noted.
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I LOAD (mA)
13.267
V O U T 1 (V )
3.3003.3113.3333.32210
1001A
3566 G28
3.289
3.278
V IN1 (V)
2.7
R E D U C T I O N B E L O W 1A (m A )
50100150200250300 3.1
3.5
3.9
4.3
3566 G29
4.7
TYPICAL PERFORMANCE CHARACTERISTICS
Buck-Boost Regulator Load Regulation
Reduction in Current Deliverability at Low V IN1
LDO3V3 (Pin 1): 3.3V LDO Output Pin. This pin provides a regulated, always-on, 3.3V supply voltage. LDO3V3 gets its power from V OUT . 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 V OUT .
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 V BUS pin. A fraction of the V BUS 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 V BUS cur-rent limit settings are available via user input which will typically correspond to the 500mA and the 100mA USB specifi cations. A multilayer ceramic averaging capacitor or R-C network is required at CLPROG for fi ltering.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 V BUS to NTC and a thermistor is required from NTC to ground. If the NTC function is not desired, the NTC pin should be grounded.
FB1 (Pin 4): Feedback Input for the (Buck-Boost) Switching Regulator . When the regulator’s control loop is complete, this pin servos to a fi xed voltage of 0.8V .V C1 (Pin 5): Output of the E rror Amplifi
er and Voltage Com-pensation Node for the (Buck-Boost) Switching Regulator . External Type I or Type III compensation (to FB1) connects to this pin. See Applications Information section for select-ing buck-boost loop compensation components.GND (Pins 6, 12): Power GND pins for the buck-boost.SWAB1 (Pin 7): Switch Node for the (Buck-Boost) Switch-ing Regulator . Connected to internal power switches A and B. External inductor connects between this node and SWCD1.
MODE (Pin 8): Logic Input. Mode enables Burst Mode functionality for the buck-boost switching regulator when pin is set high. Has a 1.6μA internal pull-down current source.
V IN1 (Pin 9): Power Input for the (Buck-Boost) Switching Regulator . This pin will generally be connected to V OUT (Pin 20). A 1μF(min) MLCC capacitor is recommended on this pin.
V OUT1 (Pin 10): Regulated Output Voltage for the (Buck-Boost) Switching Regulator .
Buck-Boost Regulator Load Step,
0mA to 300mA
CH1 V OUT1AC 100mV/DIV
CH2 I LOAD DC 200mA/DIV
100μs/DIV
V IN1 = 4.2V V OUT1 = 3.3V L = 2.2μH C OUT = 47μF
3566 G30
PIN FUNCTIONS
T A = 25°C unless otherwise noted.
PIN FUNCTIONS
SWCD1 (Pin 11): Switch Node for the (Buck-Boost) Switching Regulator. Connected to internal power switches C and D. External inductor connects between this node and SWAB1.
ILIM0 (Pin 13): Logic Input. Control pin for ILIM0 bit of the current limit of the PowerPath switching regulator. See Table 2. Active high. Has a 1.6μA internal pull-down current source.
ILIM1 (Pin 14): Logic Input. Control pin for ILIM1 bit of the current limit of the PowerPath switching regulator. See Table 2. Active high. Has a 1.6μA internal pull-down current source.
PROG (Pin 15): Charge Current Program and Charge Current Monitor Pin. Connecting a resistor from PROG to ground programs the charge current. If suffi cient in-put power is available in constant-current mode, this pin servos to 1V. The voltage on this pin always represents the actual charge current.
CHRG (Pin 16): Open-Drain Charge Status Output. The CHRG pin indicates the status of the battery charger. Four possible states are represented by CHRG: charging, not charging, unresponsive battery and battery temperature out of range. CHRG is modulated at 35kHz and switches between a low and high duty cycle for easy recognition by either humans or microprocessors. See Table 1. CHRG requires a pull-up resistor and/or LED to provide indica-tion.
GND (Pin 17): GND pin for USB Power Manager. GATE (Pin 18): Analog Output. This pin controls the gate of an optional external P-channel MOSFET transistor used to supplement the ideal diode between V OUT and BAT. The external ideal diode operates in parallel with the internal ideal diode. The source of the P-channel MOSFET should be connected to V OUT and the drain should be connected to BAT. If the external ideal diode FET is not used, GATE should be left fl oating.BAT (Pin 19): Single-Cell Li-Ion Battery Pin. Depending on available V BUS power, a Li-Ion battery on BAT will either deliver power to V OUT through the ideal diode or be charged from V OUT via the battery charger.
V OUT (Pin 20): Output Voltage of the Switching Power-Path Controller and Input Voltage of the Battery Charger. The majority of the portable product should be powered from V OUT. The L TC3566 will partition the available power between the external load on V OUT and the internal battery charger. Priority is given to the external load and any extra power is used to charge the battery. An ideal diode from BAT to V OUT ensures that V OUT is powered even if the load exceeds the allotted power from V BUS or if the V BUS power source is removed. V OUT should be bypassed with a low impedance ceramic capacitor.
V BUS (Pin 21): Primary Input Power Pin. This pin delivers power to V OUT via the SW pin by drawing controlled current from a DC source such as a USB port or wall adapter. SW (Pin 22): Power T ransmission Pin for the USB Pow-erPath. The SW pin delivers power from V BUS to V OUT via the step-down switching regulator. A 3.3μH inductor should be connected from SW to V OUT.
CHRGEN (Pin 23): Logic Input. This logic input pin inde-pendently enables the battery charger. Active low. Has a 1.6μA internal pull-down current source.
EN1 (Pin 24): Logic Input. This logic input pin independently enables the buck-boost switching regulator. Active high. Has a 1.6μA internal pull-down current source. Exposed Pad (Pin 25): Ground. Buck-boost logic and USB Power Manager ground connections. The Exposed Pad should be connected to a continuous ground plane on the printed circuit board directly under the L TC3566.
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BLOCK DIAGRAM
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OPERATION
Introduction
The L TC3566 is a highly integrated power management IC which includes a high effi ciency switch mode PowerPath controller, a battery charger, an ideal diode, an always-on LDO, and a 1A buck-boost switching regulator. The entire chip is controlled via direct digital inputs.
Designed specifi cally for USB applications, the PowerPath controller incorporates a precision average input current step-down switching regulator to make maximum use of the allowable USB power. Because power is conserved, the L TC3566 allows the load current on V OUT to exceed the current drawn by the USB port without exceeding the USB load specifi cations.
The PowerPath switching regulator and battery charger communicate to ensure that the input current never violates the USB specifi cations.
The ideal diode from BAT to V OUT guarantees that ample power is always available to V OUT even if there is insuf-fi cient or absent power at V BUS.
An “always-on” LDO provides a regulated 3.3V from avail-able power at V OUT. Drawing very little quiescent current, this LDO will be on at all times and can be used to supply up to 25mA.
The L TC3566 also has a general purpose buck-boost switching regulator, which can be independently enabled via direct digital control. Along with constant frequency PWM mode, the buck-boost regulator has a low power burst-only mode setting for signifi cantly reduced quiescent current under light load conditions.
High Effi ciency Switching PowerPath Controller Whenever V BUS is available and the PowerPath switching regulator is enabled, power is delivered from V BUS to V OUT via SW. V OUT drives both the external load (including the buck-boost regulator) and the battery charger.If the combined load does not exceed the PowerPath switching regulator’s programmed input current limit, V OUT will track 0.3V above the battery (Bat-T rack). By keeping the voltage across the battery charger low, effi ciency is optimized because power lost to the linear battery char-ger is minimized. Power available to the external load is therefore optimized.
If the combined load at V OUT is large enough to cause the switching power supply to reach the programmed input current limit, the battery charger will reduce its charge current by the amount necessary to enable the external load to be satisfi ed. Even if the battery charge current is set to exceed the allowable USB current, the USB specifi ca-tion will not be violated. The switching regulator will limit the average input current so that the USB specifi cation is never violated. Furthermore, load current at V OUT will always be prioritized and only remaining available power will be used to charge the battery.
If the voltage at BAT is below 3.3V, or the battery is not present and the load requirement does not cause the switch-ing regulator to exceed the USB specifi cation, V OUT will regulate at 3.6V, thereby providing “Instant-On” operation. If the load exceeds the available power, V OUT will drop to a voltage between 3.6V and the battery voltage. If there is no battery present when the load exceeds the available USB power, V OUT can drop toward ground.
The power delivered from V BUS to V OUT is controlled by a 2.25MHz constant-frequency step-down switching regulator. To meet the USB maximum load specifi cation, the switching regulator includes a control loop which ensures that the average input current is below the level programmed at CLPROG.
The current at CLPROG is a fraction (h CLPROG–1) of the V BUS current. When a programming resistor and an averaging capacitor are connected from CLPROG to GND, the voltage
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on CLPROG represents the average input current of the switching regulator . When the input current approaches the programmed limit, CLPROG reaches V CLPROG , 1.188V and power out is held constant.
The input current is programmed by the ILIM0 and ILIM1 pins. It can be confi gured to limit average input current to one of several possible settings as well as be deactivated (USB Suspend). The input current limit will be set by the V CLPROG servo voltage and the resistor on CLPROG ac-cording to the following expression:
I VBUS =I BUSQ +V
CLPROG R CLPROG
•(h CLPROG +1)
Figure 1 shows the range of possible voltages at V OUT as a function of battery voltage.
consists of a precision amplifi er that enables a large on-chip P-channel MOSFE T transistor whenever the voltage at V OUT is approximately 15mV (V FWD ) below the voltage at BAT . The resistance of the internal ideal diode is approxi-mately 180mΩ. If this is suffi cient for the application, then no external components are necessary. However , if more conductance is needed, an external P-channel MOSFET transistor can be added from BAT to V OUT .
When an external P-channel MOSFET transistor is present, the GATE pin of the L TC3566 drives its gate for automatic ideal diode control. The source of the external P-chan-nel MOSFET should be connected to V OUT and the drain should be connected to BAT . Capable of driving a 1nF load, the GATE pin can control an external P-channel MOSFET transistor having an on-resistance of 40mΩ or lower .Suspend LDO
If the L TC3566 is confi gured for USB suspend mode, the switching regulator is disabled and the suspend LDO provides power to the V OUT pin (presuming there is power available to V BUS ). This LDO will prevent the battery from running down when the portable product has access to a suspended USB port. Regulating at 4.6V , this LDO only becomes active when the switching converter is disabled (suspended). To remain compliant with the USB specifi ca-tion, the input to the LDO is current limited so that it will not exceed the 500μA low power suspend specifi cation. If the load on V OUT exceeds the suspend current limit, the additional current will come from the battery via the ideal diode.
OPERATION
BAT (V)
2.4
4.54.23.93.63.33.02.72.4 3.3
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2.7
3.0
3.6
4.2
V O U T (V )
Figure 1. V OUT vs BAT
Figure 2. Ideal Diode Operation
FORWARD VOL TAGE (mV) (BAT – V OUT )
C U R R E N T (m A )6001800200022001202403003566 F02
2001400100040016000120080060180360480420
Ideal Diode from BAT to V OUT
The L TC3566 has an internal ideal diode as well as a con-troller for an optional external ideal diode. The ideal diode controller is always on and will respond quickly whenever V OUT drops below BAT .
If the load current increases beyond the power allowed from the switching regulator , additional power will be pulled from the battery via the ideal diode. Furthermore, if power to V BUS (USB or wall power) is removed, then all of the application power will be provided by the battery via the ideal diode. The transition from input power to battery power at V OUT will be quick enough to allow only a 10μF capacitor to keep V OUT from drooping. The ideal diode。