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Synchronous Controller. LTC3736-2 Datasheet

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Synchronous Controller. LTC3736-2 Datasheet






LTC3736-2 Controller. Datasheet pdf. Equivalent




LTC3736-2 Controller. Datasheet pdf. Equivalent





Part

LTC3736-2

Description

Synchronous Controller

Manufacture

Linear Technology

Datasheet
Download LTC3736-2 Datasheet


Linear Technology LTC3736-2

LTC3736-2; FEATURES n No Current Sense Resistors Re quired n Out-of-Phase Controllers Reduc e Required Input Capacitance n Tracking Function n Wide VIN Range: 2.75V to 9. 8V n 0.6V ±1% Voltage Reference n High Current Limit n Constant-Frequency Cur rent Mode Operation n Low Dropout Opera tion: 100% Duty Cycle n True PLL for Fr equency Locking or Adjustment n Selecta ble Pulse-Skipping/.


Linear Technology LTC3736-2

Forced Continuous Operation n Auxiliary Winding Regulation n Internal Soft-Star t Circuitry n Power Good Output Voltage Monitor n Output Overvoltage Protectio n n Micropower Shutdown: IQ = 9μA n Ti ny Low Profile (4mm × 4mm) QFN and Na rrow SSOP Packages APPLICATIONS n One o r Two Lithium-Ion Powered Devices n Not ebook and Palmtop Computers, PDAs n Por table Instruments n Di.


Linear Technology LTC3736-2

stributed DC Power Systems LTC3736-2 Du al 2-Phase, No RSENSETM, Synchronous Co ntroller with Output Tracking DESCRIPTI ON The LTC®3736-2 is a 2-phase dual sy nchronous step-down switching regulator controller with tracking that drives e xternal complementary power MOSFETs usi ng few external components. The constan t-frequency current mode architecture w ith MOSFET VDS sens.



Part

LTC3736-2

Description

Synchronous Controller

Manufacture

Linear Technology

Datasheet
Download LTC3736-2 Datasheet




 LTC3736-2
FEATURES
n No Current Sense Resistors Required
n Out-of-Phase Controllers Reduce Required
Input Capacitance
n Tracking Function
n Wide VIN Range: 2.75V to 9.8V
n 0.6V ±1% Voltage Reference
n High Current Limit
n Constant-Frequency Current Mode Operation
n Low Dropout Operation: 100% Duty Cycle
n True PLL for Frequency Locking or Adjustment
n Selectable Pulse-Skipping/Forced Continuous
Operation
n Auxiliary Winding Regulation
n Internal Soft-Start Circuitry
n Power Good Output Voltage Monitor
n Output Overvoltage Protection
n Micropower Shutdown: IQ = 9μA
n Tiny Low Profile (4mm × 4mm) QFN and Narrow
SSOP Packages
APPLICATIONS
n One or Two Lithium-Ion Powered Devices
n Notebook and Palmtop Computers, PDAs
n Portable Instruments
n Distributed DC Power Systems
LTC3736-2
Dual 2-Phase, No RSENSETM,
Synchronous Controller
with Output Tracking
DESCRIPTION
The LTC®3736-2 is a 2-phase dual synchronous step-down
switching regulator controller with tracking that drives
external complementary power MOSFETs using few ex-
ternal components. The constant-frequency current mode
architecture with MOSFET VDS sensing eliminates the need
for sense resistors and improves efficiency. Power loss and
noise due to the ESR of the input capacitance are minimized
by operating the two controllers out-of-phase.
Pulse-skipping operation provides high efficiency at light
loads. 100% duty cycle capability provides low dropout
operation, extending operating time in battery-powered
systems.
The switching frequency can be programmed up to 750kHz,
allowing the use of small surface mount inductors and
capacitors. For noise sensitive applications, the LTC3736-2
switching frequency can be externally synchronized from
250kHz to 850kHz. An internal soft-start, which can be
lengthened externally, smoothly ramps the output voltage
during start-up.
The LTC3736-2 is available in the tiny thermally enhanced
(4mm × 4mm) QFN and 24-lead narrow SSOP packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 5481178,
5929620, 6144194, 6580258, 6304066, 6611131, 6498466.
TYPICAL APPLICATION
High Efficiency, 2-Phase, Dual Synchronous DC/DC Step-Down Converter
VOUT1
2.5V
2.2μH
187k
220pF
47μF
59k
VIN
SENSE1+ SENSE2+
TG1
TG2
SW1
SW2
LTC3736-2
BG1
BG2
PGND
PGND
VFB1
VFB2
ITH1
ITH2
SGND
15k
10μF
s2
VIN
2.75V TO 9.8V
2.2μH
118k
220pF
15k
59k
VOUT2
1.8V
47μF
37362 TA01a
Efficiency and Power Loss
vs Load Current (Figure 15 Circuit)
100
10
VOUT = 2.5V
95
90
EFFICIENCY
1
85
80
75
0.1
POWER LOSS
70
65
0.01
60
55
50
1
10
100
1000
LOAD CURRENT (mA)
0.001
10000
37362 TA01b
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 LTC3736-2
LTC3736-2
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage (VIN) ........................ –0.3V to 10V
PLLLPF, RUN/SS, SYNC/FCB,
TRACK, SENSE1+, SENSE2+,
IPRG1, IPRG2 Voltages................. –0.3V to (VIN + 0.3V)
VFB1, VFB2, ITH1, ITH2 Voltages ................. –0.3V to 2.4V
SW1, SW2 Voltages ........... –2V to VIN + 1V or 10V Max
PGOOD...................................................... –0.3V to 10V
TG1, TG2, BG1, BG2 Peak Output Current (<10μs) .... 1A
Operating Temperature Range (Note 2) .... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Junction Temperature (Note 3) ............................ 125°C
Lead Temperature (Soldering, 10 sec)
(LTC3736EGN-2)................................................... 300°C
PIN CONFIGURATION
SW1 1
IPRG1 2
VFB1 3
ITH1 4
IPRG2 5
PLLLPF 6
SGND 7
VIN 8
TRACK 9
VFB2 10
ITH2 11
PGOOD 12
TOP VIEW
24 SENSE1+
23 PGND
22 BG1
21 SYNC/FCB
20 TG1
19 PGND
18 TG2
17 RUN/SS
16 BG2
15 PGND
14 SENSE2+
13 SW2
GN PACKAGE
24-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 130°C/W
TOP VIEW
24 23 22 21 20 19
ITH1 1
IPRG2 2
PLLLPF 3
SGND 4
VIN 5
TRACK 6
18 SYNC/FCB
17 TG1
16 PGND
25
15 TG2
14 RUN/SS
13 BG2
7 8 9 10 11 12
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
TJMAX = 125°C, θJA = 37°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3736-2EGN#PBF
LTC3736-2EGN#TRPBF
24-Lead Plastic SSOP
LTC3736-2EUF#PBF
LTC3736-2EUF#TRPBF 37362
24-Lead (4mm × 4mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
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 LTC3736-2
LTC3736-2
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 4.2V unless otherwise specified.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loops
Input DC Supply Current
Normal Mode
Shutdown
UVLO
Undervoltage Lockout Threshold
Shutdown Threshold at RUN/SS
(Note 4)
RUN/SS = VIN
RUN/SS = 0V
VIN = UVLO Threshold –200mV
VIN Falling
VIN Rising
4.75 750
μA
9
20
μA
3
10
μA
l 1.95 2.25 2.55
V
l 2.15 2.45 2.75
V
0.45 0.65 0.85
V
Start-Up Current Source
RUN/SS = 0V
0.4
0.7
1
μA
Regulated Feedback Voltage
0°C to 85°C (Note 5)
–40°C to 85°C
0.594 0.6 0.606
V
l 0.591 0.6 0.609
V
Output Voltage Line Regulation
Output Voltage Load Regulation
VFB1,2 Input Current
TRACK Input Current
2.75V < VIN < 9.8V (Note 5)
ITH = 0.9V (Note 5)
ITH = 1.7V
(Note 5)
TRACK = 0.6V
0.05
0.2
0.12
0.5
–0.12 –0.5
10
50
10
50
mV/ V
%
%
nA
nA
Overvoltage Protect Threshold
Measured at VFB
0.66 0.68
0.7
V
Overvoltage Protect Hysteresis
20
mV
Auxiliary Feedback Threshold
SYNC/FCB Ramping Positive
0.525 0.6 0.675
V
Top Gate (TG) Drive 1, 2 Rise Time
Top Gate (TG) Drive 1, 2 Fall Time
Bottom Gate (BG) Drive 1, 2 Rise Time
CL = 3000pF
CL = 3000pF
CL = 3000pF
40
ns
40
ns
50
ns
Bottom Gate (BG) Drive 1, 2 Fall Time
Maximum Current
(SENSE+ – SW)
Sense
Voltage
(ΔVSENSE(MAX))
Soft-Start Time
Oscillator and Phase-Locked Loop
CL = 3000pF
IPRG = Floating
IPRG = 0V
IPRG = VIN
Time for VFB1 to Ramp from 0.05V to 0.55V
40
ns
l 220
240
260
mV
l 150
167
185
mV
l 320
345
370
mV
0.667 0.833
1
ms
Oscillator Frequency
Phase-Locked Loop Lock Range
Unsynchronized (SYNC/FCB Not Clocked)
PLLLPF = Floating
PLLLPF = 0V
PLLLPF = VIN
SYNC/FCB Clocked
Minimum Synchronizable Frequency
Maximum Synchronizable Frequency
480
550
600
kHz
260
300
340
kHz
650
750
825
kHz
l
200
250
kHz
l 850 1150
kHz
Phase Detector Output Current
Sinking
Sourcing
PGOOD Output
fOSC > fSYNC/FCB
fOSC < fSYNC/FCB
–4
μA
4
μA
PGOOD Voltage Low
PGOOD Trip Level
IPGOOD Sinking 1mA
VFB with Respect to Set Output Voltage
VFB < 0.6V, Ramping Positive
VFB < 0.6V, Ramping Negative
VFB < 0.6V, Ramping Negative
VFB < 0.6V, Ramping Positive
125
mV
–13 –10
–7
%
–16 –13.3 –10
%
7
10
13
%
10
13.3
16
%
37362fb
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