TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Step-Down Regulator–2.25MHz
The LTC ®3545/LTC3545-1 are triple, high efficiency, monolithic synchronous buck regulators using a constant frequency, current mode architecture. The regulators op-erate independently with parate run pins. The 2.25V to 5.5V input voltage range makes the L TC3545/L TC3545-1 well suited for single Li-Ion battery-powered applications. Low ripple pul skip mode or high effi ciency Burst Mode operation is externally lectable. PWM pul skip mode operation provides very low output ripple voltage while Burst Mode operation increas effi ciency at low output loads.
Switching frequency is internally t to 2.25MHz, or the switching frequency can be synchronized to an external 1MHz to 3MHz clock. Power good indicators easily allow power on quencing between the three regulators.The internal synchronous switches increa effi ciency and eliminate external Schottky diodes. Low output voltages are supported with the 0.6V feedback reference voltage.The L TC3545-1 replaces the SYNC/MODE function with a third PGOOD pin and forces Burst Mode operation.
■
Three 800mA Outputs ■ High Effi ciency: Up to 95%
■ 2.25V to 5.5V Input Voltage Range
■
Low Ripple (<20mV P-P ) Burst Mode ® Operation I Q : 58μA
■
2.25MHz Constant Frequency Operation or
■ Synchronizable to External 1MHz to 3MHz Clock ■ Power Good Indicators Ea Supply Sequencing ■ 0.6V Reference Allows Low Output Voltages
■ Current Mode Operation/Excellent T ransient Respon ■
Low Profi le 16-Lead 3mm × 3mm QFN Package
■
Smart Phones
■ Wireless and DSL Modems ■ Digital Still Cameras ■ Portable Instruments ■ Point of Load Regulation
High Effi ciency T riple Step-Down Converter with Power Sequencing
Effi ciency and Loss vs Load Current
L , L T , L TC, L TM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6580258, 5481178, 6127815, 6498466, 6611131.
V OUT11.8V V IN
V OUT2
1.2V
V OUT31.5V LOAD CURRENT (A)
30E F F I C I E N C Y (%)
LOSS (W)
901002010
80507060400.0001
0.010.11
3545 TA01b
00.001
1
0.1
0.01
0.0001
0.001
T A = 25°C V OUT = 2V
Burst Mode OPERATION f OSC = 2.25MHz SINGLE CHANNEL
ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage ....................................–0.3V to 6V RUNx, PGOODx .............................–0.3V to (V IN + 0.3V)V FBx , SYNC/MODE ........................–0.3V to (V IN + 0.3V)SWx ..............................................–0.3V to (V IN + 0.3V)P-Switch Source Current (DC) (Note 8) ...............
....1.1A (Note 1)
SYMBOL PARAMETER CONDITIONS
MIN TYP MAX UNITS
General Characteristics
V IN Input Voltage Range
● 2.25 5.5
V V FBx
Regulated Feedback Voltage (Note 5)
T A = 25°C
0°C ≤ T A ≤ 85°C
孕妇能游泳吗
L TC3545IUD; –40°C < T A < 125°C ●●0.5920.5880.588
0.60.60.60.6080.6120.612V V V ΔV FBx
Reference Voltage Line Regulation (Note 5)
V IN = 2.25V to 5.5V ●
0.08
0.15
%/V
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwi specifi cations are at T A = 25°C. V IN = PV IN = 3.6V unless otherwi noted. (Note 2)
N-Channel Sink Current (DC) (Note 8) .....................1.1A Peak SW Sink and Source Current (Note 8) .............1.3A Operating Junction Temperature Range
(Note 2) .............................................–40°C to 125°C Storage Temperature Range ...................–65°
C to 125°C
L TC3545
L TC3545-1
16151413
567817
UD PACKAGE
16-LEAD (3mm s 3mm) PLASTIC QFN
TOP VIEW 9
1011124
321SW1PGOOD1RUN2PGOOD2V FB2V FB3RUN3SYNC/MODE
G N D A
V I N
R U N 1
V F B 1
S W 2
P G N D
P V I N
S W 3T JMAX = 125°C, θJA = 55°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
16151413
5678TOP VIEW 17
UD PACKAGE
16-LEAD (3mm s 3mm) PLASTIC QFN
9
1011124
321SW1PGOOD1RUN2PGOOD2V FB2
V FB3RUN3PGOOD3
G N D A
V I N
R U N 1
V F B 1
S W 2
P G N D
P V I N
S W 3
T JMAX = 125°C, θJA = 55°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
LEAD FREE FINISH TAPE AND REEL PART MARKING*PACKAGE DESCRIPTION
TEMPERATURE RANGE L TC3545EUD#PBF L TC3545EUD#TRPBF LCSR 16-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C L TC3545IUD#PBF L TC3545IUD#TRPBF LCSR 16-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C L TC3545EUD-1#PBF L TC3545EUD-1#TRPBF LDDP 16-Lead (3mm × 3mm) Plastic QFN –40°C to 125°C L TC3545IUD-1#PBF
L TC3545IUD-1#TRPBF
LDDP
16-Lead (3mm × 3mm) Plastic QFN
–40°C to 125°C
Consult L TC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container .Consult L TC Marketing for information on non-standard lead bad fi nish parts.For more information on lead free part marking, go to: www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: www.linear .com/tapeandreel/
ORDER INFORMATION
Note 1: Stress beyond tho listed under Absolute Maximum Ratings may cau permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.
Note 2: The LTC3545E/LTC3545E-1 are guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3545I/LTC3545I-1
are guaranteed to meet performance specifi cations over the full –40°C to 125°C operating junction temperature range.Note 3: T J is calculated from the ambient temperature T A and power dissipation P D according to the following formula: T J = T A + (P D )(68°C/W)
This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature
SYMBOL PARAMETER
CONDITIONS MIN TYP MAX UNITS
V LOADREG Output Voltage Load Regulation (Notes 5, 6)0.5
%I FBx Feedback Pin Leakage (Note 5)
80
nA I S
Input DC Bias Current (All Regulators Enabled)
Pul Skip (Active Mode)
Burst Mode Operation (All Regulators Sleeping)Shutdown (RUN X = 0V)I LOAD = 0A, 2.25MHz V FBx = 0.5V V FBx = 0.7V
680580.1
750702.0μA μA μA f OSC Oscillator Frequency ●
1.8
2.25
2.7MHz f SYNC Synchronization Frequency L TC3545 Only
管理学学什么
●13MHz V RUN(HIGH)RUNx Input High Voltage ●1
V V RUN(LOW)RUNx Input Low Voltage ●
0.3
V I RUNx RUN Leakage Current ±0.1±1μA I LSWx SWx Leakage V RUNx = 0V , V SWx = 0V or 5.5V , V IN = 5.5V ±0.1±1μA I SYNC SYNC Leakage
V RUN = 0V , V SYNC = 0V or 5.5V ,V IN = 5.5V ±0.1±1
μA T PGOODx Power Good Threshold–Deviation From V FB Steady State (0.6V)
V FBx Ramping Up V FBx Ramping Down –7.5–10%%
R PGOODx
Power Good Pull-Down On-Resistance
I PGD = 50mA
●
1450ΩMODE/SYNC Thresholds
0.93
V
Individual Regulator Characteristics (One Regulator Enabled)t SS Soft-Start Period V FBx = 10% to 90% Fullscale
8501100μs I PK Peak Switch Current Limit 1
1.3 1.6
A I Q
Input DC Bias Current Pul Skip (Active Mode)
Burst Mode Operation (Sleeping)I LOAD = 0A, 2.25MHz V FBx = 0.5V V FBx = 0.7V 31031μA μA R PFET R DS(ON) of P-Channel FET (Note 7)I SWx = 100mA 0.35ΩR NFET R DS(ON) of N-Channel FET (Note 7)I SWx = –100mA 0.35Ω
V UVLO
Undervoltage Lockout
(High V CC to Low)
●
1.8
2.25V
ELECTRICAL CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating
temperature range, otherwi specifi cations are at T A = 25°C. V IN = PV IN = 3.6V unless otherwi noted. (Note 3)
will exceed 125°C when overtemperature is active. Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability.
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 is active. Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability.
Note 5: The L TC3545/L TC3545-1 are tested in a proprietary test mode that connects V FB to the output of the error amplifi er .
Note 6: Load regulation is inferred by measuring the regulation loop gain.Note 7: The QFN switch-on resistance is guaranteed by correlation to water level measurements.
Note 8: Guaranteed by long-term current density limitations.
Burst Mode Operation
Effi ciency vs Supply Voltage
Supply Current vs Temperature Burst Mode Operation
TYPICAL PERFORMANCE CHARACTERISTICS
V REF vs Temperature at 2.25V , 3.6V , 5.5V
Switching Frequency vs Supply Voltage and Temperature
Load Regulation, All Channels
TEMPERATURE (°C)
–50
0.585
V R E F (V )
0.5900.5950.6000.6050.6100.615
50150
100
3545 G01
SUPPLY VOLTAGE (V)
2
1.5
S W I T C H I N G F R E Q U E N C Y (M H z )
2.0
2.5
3.0
343545 G02
56
LOAD CURRENT (mA)
00.60.81.2600
3545 G03
0.40.2200
400800
0–0.4
–0.2
1.0V O U T E
R R O R (%
)
1μs/DIV
SW 2V/DIV I L
100mA/DIV
V OUT 20mV/DIV 3545 G04
V IN = 3.6V V OUT = 1.8V I LOAD = 50mA f OSC = 2.25MHz
SUPPLY VOLTAGE (V)
经典华语电影2E F F I C I E N C Y (%)
90
95
6
3545 G05
85
80
34
5100
TEMPERATURE (°C)
S U P P L Y C U R R E N T (μA )
20603545 G06
如何测智商10
305040
–50
50150
100
TYPICAL PERFORMANCE CHARACTERISTICS
Channel 1 Load Step Respon Channel 2 Load Step Respon Channel 3 Load Step Respon
Supply Current vs Temperature, Pul Skipping
Effi ciency vs Load Current,Burst Mode Operation
Effi ciency vs Load Current,Pul Skipping Operation
TEMPERATURE (°C)
150S U P P L Y C U R R E N T (μA )
200
2503003504503545 G07
400
杭州西湖风景
–50
50150
100
LOAD CURRENT (mA)
30E F F I C I E N C Y (%)
901002010
80507060400.1
10100
1000
3545 G08
1
LOAD CURRENT (mA)
30E F F I C I E N C Y (%)
90100201080507060400.1
10100
1000
3545 G09
1
10μs/DIV I LOAD 500mA/DIV
I L
500mA/DIV V OUT1100mV/DIV 3545 G10
T A = 25°C V IN = 3.6V V OUT
t是什么意思= 1.2V
LOAD STEP 0mA TO 600mA Burst Mode OPERATION
10μs/DIV I LOAD 500mA/DIV
I L
心动一刻500mA/DIV V OUT2100mV/DIV 3545 G11
T A = 25°C V IN = 3.6V V OUT
= 1.5V
LOAD STEP 0mA TO 600mA Burst Mode OPERATION
10μs/DIV I LOAD 500mA/DIV
I L
500mA/DIV V OUT3100mV/DIV 3545 G12
T A = 25°C
吃红豆的好处V IN = 3.6V V OUT = 1.8V
LOAD STEP 0mA TO 600mA Burst Mode OPERATION
