LOAD CURRENT (A)
E F F I C I E N C Y (%)
POWER LOSS (W)100
80
75
9590857010010
10.10.01
0.0001
0.0013546 TA01b
OUT1, 1A
V 2.5V V TYPICAL APPLICATION
FEATURES
APPLICATIONS
or 2A/2A Confi gurable
Step-Down DC/DC Regulator
The L TC ®3546 is a dual, constant frequency, synchronous step down, DC/DC converter for medium power applica-tions. The design consists of a 2A and a 1A primary output switch. In addition to the 2A/1A capability, a 1A dependant output switch can be externally connected to either of the primary outputs to produce 3A/1A dual regulator or 2A/2A dual regulator confi gurations.Supply operation is from 2.25V to 5.5V . Switching frequency can be set to 2.25MHz, adjustable 0.75MHz to 4MHz, or synchronized to an external clock. E ach output is adjustable from 0.6V to 5V and has turn-on supply tracking. Internal synchronous low R DS(ON), power switches provide high effi ciency without external Schottky diodes.
User selectable modes (Burst Mode ® operation, pulse skip, and forced continuous) allow trade-off between ripple noise and low power effi ciency. Burst Mode operation provides high effi ciency at light loads. Pulse skip mode provides low ripple noise at light loads.
The device is capable of low dropout confi gurations and both channels can operate at 100% duty cycle. In shut-down, the device draws <1μA.
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.
n
V IN Range: 2.25V to 5.5V n V OUT Range: 0.6V to 5V
n Programmable Frequency Operation; 2.25MHz, or Adjustable Between 0.75MHz to 4MHz n Low R DS(ON) Internal Switches n High Effi ciency: Up to 96%n No Schottky Diodes Required n Short-Circuit Protected
n Current Mode Operation for Excellent Line and Load T ransient Response
n Low Ripple Burst Mode Operation (<30mV P-P ), I Q = 160μA
n Ultralow Shutdown Current: I Q
< 1μA n Low Dropout Operation: 100% Duty Cycle n Power Good Output For Each Channel
n Externally or Internally Programmable Burst Level n External or Internal Soft-Start or Supply T racking n Available in 28-Lead (4mm × 5mm) QFN Package
n
PDAs/Ultra-Mobile PCs n Digital Cameras n PC Cards
n Wireless and DSL Modems
n Point of Load DC/DC Conversion
OUT2 Effi ciency (Burst Mode Operation)
ELECTRICAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
V IN1, V IN1D , V IN2, V CCA , V CCD Voltages .........–0.3V to 6V SYNC/MODE, SW1, SW1D, SW2A, SW2B, RUN1, RUN2, V FB1, V FB2, PHASE, FREQ, I TH1, I TH2, TRACK/SS1, TRACK/SS2, BMC1,
BMC2 Voltages ............–0.3V to (V IN1 or V IN2) + 0.3V Maximum Difference Between Any of
V IN1, V IN1D , V IN2, V CCA , V CCD ..............................0.3V PGOOD1, PGOOD2 Voltage ..........................–0.3V to 6V Operating Junction Temperature Range
(Notes 2, 6, 7) ........................................–40°C to 125°C Storage Temperature Range ...................–65°C to 125°C
(Note 1)
910TOP VIEW UFD PACKAGE
28-LEAD (4mm s 5mm) PLASTIC QFN
11121328272625241423
65432
1BMC2TRACK/SS2V FB2I TH2V CCD RUN2V IN2V IN1BMC1TRACK/SS1V FB1
I TH1PHASE RUN1PGND2PGND1
P G O O D 2
S Y N C /M O D E V C C A
G N D A
F R E Q
P G O O D 1
V I N 1D
S W 2A
S W 2B
S W 1D
S W 1
P G N D 1D
71718192029
2122168
15T JMAX = 125°C, θJA = 34°C/W EXPOSED PAD (PIN 29) IS GNDD
The l denotes the specifi cations which apply over the full operating
junction temperature range, otherwise specifi cations are at T A = 25°C. V IN = V CCA = 3.6V , unless otherwise specifi ed. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V IN1, V IN1D , V IN2, V CCA , V CCD Operating Voltage Range V IN1 = V IN1D = V IN2 = V CCA = V CCD 2.25
5.5V I FB1, I FB2Feedback Pin Input Current (Note 3)±0.1
μA V FB1, V FB2Feedback Voltage
(Note 3)
l
0.5880.60.612V ΔV LINEREG Reference Voltage Line Regulation %/V is The Percentage Change in V OUT with a Change in V IN
V IN = 2.25V to 5.5V (Note 3)
0.04
0.2
%/V
ΔV LOADREG Output Voltage Load Regulation I TH1, I TH2 = 0.36V (Note 3)
I TH1, I TH2 = 0.84V (Note 3)l l 0.02–0.020.2–0.2%%g m(EA)
Error Amplifi er T ransconductance
(Note 3)
1400
μS
P IN CONFIGURATION ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING*PACKAGE DESCRIPTION
TEMPERATURE RANGE L TC3546EUFD#PBF L TC3546EUFD#TRPBF 354628-Lead (4mm × 5mm) Plastic QFN –40°C to 85°C L TC3546IUFD#PBF L TC3546IUFD#TRPBF 3546
28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING*PACKAGE DESCRIPTION
TEMPERATURE RANGE L TC3546EUFD L TC3546EUFD#TR 354628-Lead (4mm × 5mm) Plastic QFN –40°C to 85°C L TC3546IUFD
L TC3546IUFD#TR
ldap
目录服务器
3546
28-Lead (4mm × 5mm) Plastic QFN
–40°C to 125°C藏文网站
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 .For more information on lead free part marking, go to: www.linear /leadfree/ For more information on tape and reel specifi cations, go to: www.linear /tapeandreel/
ELECTRICAL CHARACTERISTICS
The
l denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at T A = 25°C. V IN = V CCA = 3.6V, unless otherwise specifi ed. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V TRACK/SS1,
V TRACK/SS2
T racking Voltage Offset V TRACK/SS1,2 = 0.3V15mV
I TRACK/SS1,
I TRACK/SS2
T racking Current Source V TRACK/SS1,2 = 0V0.8 1.15 1.5μA I S Input DC Supply Current (Note 4)
Active Mode V FB1 = V FB2 = 0.55V, V MODE = V IN,
V RUN1 = V RUN2 = V IN
600990μA
Half Active Mode (V RUN1 = V IN, V RUN2 = 0)V FB1 = 0.55V, V MODE = V IN, V RUN1 = V IN,
V RUN2 = 0V
400800μA
Half Active Mode (V RUN1 = 0, V RUN2 = V IN)V FB2 = 0.55V, V MODE = V IN, V RUN1 = 0V,
V RUN2 = V IN
文姜400800μA
Both Channels in Sleep Mode V FB1 = V FB2 = 1V, V MODE = V IN,
V RUN1 = V RUN2 = V IN
160300μA Shutdown V RUN1 = V RUN2 = 0V0.21μA
f OSC Oscillator Frequency V FREQ: R T = V IN
V FREQ: R T = 143k
V FREQ: Resistor (Note 5)l
1.8
1.2
0.75
2.25
1.5
2.9
1.8
4
MHz
MHz
MHz
I LIM1Peak Switch Current Limit on SW1 (1A)BMC1 = V IN, V ITH1 = 1.3V
BMC1 = 0.4V, V ITH1 = 0V 1.4 1.6
0.45
A
A
I LIM2Peak Switch Current Limit on SW2A/B
(2A)BMC2 = V IN, V ITH1 = 1.3V
BMC2 = 0.4V, V ITH1 = 0V
2.8
3.2
0.9
A
A
I LIM1+1D Peak Switch Current Limit on
SW1 + SW1D (2A)SW1 externally connected to SW1D
BMC1 = V IN (Note 8)
BMC1 = 0.4V (Note 8)
2.5
3.2
1.6
A
A
I LIM2+1D Peak Switch Current Limit on
SW2A/B + SW1D (3A)SW2A/B externally connected to SW1D
BMC2 = V IN (Note 8)
BMC2 = 0.4V (Note 8)
3.75
4.8
2.4
A
A
R DS(ON)1SW1 Top Switch On-Resistance (1A)
SW1 Bottom Switch On-Resistance V IN2 = 3.6V
V IN2 = 3.6V
0.19
0.18
Ω
Ω
R DS(ON)1D SW1D Top Switch On-Resistance (1A)
SW1D Bottom Switch On-Resistance V IN2 = 3.6V
V IN2 = 3.6V
0.19
0.17
Ω
Ω
R DS(ON)2SW2A/B Top Switch On-Resistance (2A)
SW2A/B Bottom Switch On-Resistance V IN1 = 3.6V
V IN1 = 3.6V
0.096
0.085
Ω
Ω
I SW1(LKG)Switch Leakage Current SW1V IN = 6V
V ITH1 = 0V
V RUN1 = 0V
0.011μA
I SW1D(LKG)Switch Leakage Current SW1D V IN = 6V
V ITH1 = V ITH2 = 0V
V RUN1 = V RUN2 = 0V
0.011μA
I SW2A/B(LKG)Switch Leakage Current SW2A/B V IN = 6V
V ITH2 = 0V
V RUN2 = 0V
0.011μA
V UVLO Undervoltage Lockout Threshold V IN1, V IN2, V CCA, V CCD Rising
V IN1, V IN2, V CCA, V CCD Falling 2.03
1.86
2.14
1.97
2.2
2.03
V
V
中国现代
医学杂志ELECTRICAL CHARACTERISTICS
The
l denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at T A = 25°C. V IN = V CCA = 3.6V, unless otherwise specifi ed. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS T PGOOD1Threshold for Power Good
Percentage Deviation from Regulated V FB1
(Typically 0.6V).
V FB1 Ramping Up, V SYNC/MODE = 0V–8%
T PGOOD2Threshold for Power Good
Percentage Deviation from Regulated V FB2
(Typically 0.6V).
V FB2 Ramping Up, V SYNC/MODE = 0V–8%
R PGOOD1Power Good Pull-Down On-Resistance132300ΩR PGOOD2Power Good Pull-Down On-Resistance132300Ωt SS Soft-Start Internal Time.V OUT from 0% to 95%, V TRACK/SS is
fl oating
0.8 1.2 1.9ms
V RUN1, V RUN2,
V PHASE
RUN1, RUN2, and PHASE Threshold0.30.8 1.2V
I RUN1, I RUN2,
I PHASE
RUN1, RUN2, and PHASE Leakage Current±0.01±1μA
VTL SYNC/MODE SYNC/MODE Threshold Voltage Low to Put
the Part Into Pulse Skipping Mode
0.5V
VTH SYNC/MODE SYNC/MODE Threshold Voltage High to
Put the Part Into Burst Mode Operation
V IN – 0.5V
V SYNC/MODE SYNC/MODE Threshold for Clock
Synchronization
0.30.8 1.2V
I SYNC/MODE SYNC/MODE Leakage Current±0.01±1μA VTH FREQ FREQ Threshold Voltage High V IN – 0.85V I BMC1, I BMC2BMC1, BMC2 Leakage Current V IN = 6V, V BMC = 3V±0.4μA
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 TC3546E is 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 L TC3546I is guaranteed to meet performance specifi cations over the full –40°C to 125°C operating junction temperature range
Note 3: The L TC3546 is tested in feedback loop which servos V FB1 to the midpoint for the error amplifi er (V ITH1 = 0.6V) and V FB2 to the midpoint for the error amplifi er (V ITH2 = 0.6V).
Note 4: Total supply current is higher due to the internal gate charge being delivered at the switching
frequency.Note 5: Variable frequency operation with resistor is guaranteed by design and is subject to duty cycle limitations.
Note 6: 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 above the specifi ed maximum operating junction temperature may impair device reliability.
Note 7: 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 • 34°C/W)
Note 8: Minimum current limit is guaranteed by design and correlation to the R DS(ON)1D, I LIM1 and I LIM2 measurements.
TYPICAL PERFORMANCE CHARACTERISTICS
OUT1 Burst Mode Operation
公民道德
建设的原则
OUT1 Pulse Skipping Mode Operation
OUT1 Forced Continuous Mode Operation
OUT1 Burst Mode Operation
OUT1 Pulse Skipping Mode Operation OUT1 Forced Continuous Mode
Operation
2μs/DIV
V OUT 20mV/DIV
I LOAD 500mA/DIV
3546 G02
SW1D CONNECTED TO SW1V IN = 3.6V V OUT = 1.8V I LOAD
= 300mA
1μs/DIV
V OUT 20mV/DIV
I LOAD 250mA/DIV
3546 G03
SW1D CONNECTED TO SW1V IN = 3.6V V OUT = 1.2V I LOAD = 100mA
T
V
D
V
SW1D CONNECTED TO SW1V IN = 3.6V V OUT = 1.2V I LOAD = 100mA
T
V
D
V
SW1D CONNECTED TO SW2V IN = 3.6V V OUT = 1.8V I LOAD = 200mA T
V
D
V
SW1D CONNECTED TO SW2V IN = 3.6V V OUT = 1.2V I LOAD = 100mA T
V
D
V
SW1D CONNECTED TO SW2V IN = 3.6V V OUT = 1.2V I LOAD = 50mA
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