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Synchronous Controller. LTC3736-1 Datasheet

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Synchronous Controller. LTC3736-1 Datasheet






LTC3736-1 Controller. Datasheet pdf. Equivalent




LTC3736-1 Controller. Datasheet pdf. Equivalent





Part

LTC3736-1

Description

Synchronous Controller

Manufacture

Linear Technology

Datasheet
Download LTC3736-1 Datasheet


Linear Technology LTC3736-1

LTC3736-1; LTC3736-1 Dual 2-Phase, No RSENSETM, Syn chronous Controller with Spread Spectru m U U FEATURES ■ Spread Spectrum Op eration ■ Tracking Function ■ No Cu rrent Sense Resistors Required ■ Out- of-Phase Controllers Reduce Required In put Capacitance ■ Wide VIN Range: 2.7 5V to 9.8V ■ Current Mode Operation 0.6V ±1.5% Voltage Reference ■ Lo w Dropout Operation: 100% Duty Cycl.


Linear Technology LTC3736-1

e ■ Pulse Skipping Operation at Light Loads ■ Internal Soft-Start Circuitry ■ Power Good Output Voltage Monitor ■ Output Overvoltage Protection ■ M icropower Shutdown: IQ = 9µA ■ Tiny Low Profile (4mm × 4mm) QFN and Narrow SSOP Packages U APPLICATIO S ■ One o r Two Lithium-Ion Powered Devices ■ N otebook and Palmtop Computers, PDAs ■ Portable Instruments ■ Distributed DC.


Linear Technology LTC3736-1

Power Systems , LTC and LT are register ed trademarks of Linear Technology Corp oration. No RSENSE is a trademark of Li near Technology Corporation. Protected by U.S. Patents including 5481178, 5929 620, 6144194, 6580258, 6304066, 6611131 , 6498466. DESCRIPTIO The LTC®3736-1 is a 2-phase dual synchronous stepdown switching regulator controller with tra cking that drives e.



Part

LTC3736-1

Description

Synchronous Controller

Manufacture

Linear Technology

Datasheet
Download LTC3736-1 Datasheet




 LTC3736-1
LTC3736-1
Dual 2-Phase, No RSENSETM,
Synchronous Controller with
Spread Spectrum
FEATURES
Spread Spectrum Operation
Tracking Function
No Current Sense Resistors Required
Out-of-Phase Controllers Reduce Required
Input Capacitance
Wide VIN Range: 2.75V to 9.8V
Current Mode Operation
0.6V ±1.5% Voltage Reference
Low Dropout Operation: 100% Duty Cycle
Pulse Skipping Operation at Light Loads
Internal Soft-Start Circuitry
Power Good Output Voltage Monitor
Output Overvoltage Protection
Micropower Shutdown: IQ = 9µA
Tiny Low Profile (4mm × 4mm) QFN and Narrow
SSOP Packages
U
APPLICATIO S
One or Two Lithium-Ion Powered Devices
Notebook and Palmtop Computers, PDAs
Portable Instruments
Distributed DC Power Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
No RSENSE is a trademark of Linear Technology Corporation.
Protected by U.S. Patents including 5481178, 5929620, 6144194, 6580258, 6304066,
6611131, 6498466.
DESCRIPTIO
The LTC®3736-1 is a 2-phase dual synchronous step-
down switching regulator controller with tracking that
drives external complementary power MOSFETs using
few external 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 capaci-
tance are minimized by operating the two controllers out
of phase.
A unique spread spectrum architecture randomly varies
the LTC3736-1’s switching frequency from 450kHz to
580kHz, significantly reducing the peak radiated and con-
ducted noise on both the input and output supplies,
making it easier to comply with electromagnetic interfer-
ence (EMI) standards.
Pulse skipping operation provides high efficiency at light
loads. 100% duty cycle capability provides low dropout op-
eration, extending operating time in battery-powered sys-
tems. The high switching frequencies allow for the use of
small surface mount inductors and capacitors.
The LTC3736-1 is available in the low profile (0.75mm)
24-pin thermally enhanced (4mm × 4mm) QFN package
and 24-lead narrow SSOP packages.
TYPICAL APPLICATIO
Low Noise, 2-Phase, Dual Synchronous DC/DC Step-Down Converter
VIN
SENSE1+ SENSE2+
10µF
×2
VIN
2.75V TO 9.8V
2.2µH
TG1
TG2
SW1
SW2
LTC3736-1
BG1
BG2
2.2µH
VOUT1
2.5V
+
187k
47µF
220pF
59k
PGND
PGND
VFB1
VFB2
ITH1
ITH2
SGND
15k
220pF
15k
118k
+
59k
VOUT2
1.8V
47µF
37361 TA01a
Output Voltage Frequency
Spectrum
–10
FIGURE 13 CIRCUIT SPREAD SPECTRUM
–20 VOUT = 2.5V
DISABLED
–30 RBW = 30Hz
SPREAD SPECTRUM
–40
ENABLED
–50
–60
–70
–80
–90
–100
–110
410k 450k 490k 530k 570k 610k
FREQUENCY (Hz)
37361 TA01b
37361f
1





 LTC3736-1
LTC3736-1
ABSOLUTE AXI U RATI GS (Note 1)
Input Supply Voltage (VIN) ........................ – 0.3V to 10V
FREQ, RUN/SS, SSDIS,
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-1) .................................................. 300°C
UW U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
24 23 22 21 20 19
ITH1 1
IPRG2 2
FREQ 3
SGND 4
VIN 5
TRACK 6
18 SSDIS
17 TG1
16 PGND
25
15 TG2
14 RUN/SS
13 BG2
7 8 9 10 11 12
ORDER PART
NUMBER
LTC3736EUF-1
UF PART MARKING
3736-1
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
TJMAX = 125°C, θJA = 37°C/W
EXPOSED PAD (PIN 25) IS PGND
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
SW1 1
IPRG1 2
VFB1 3
ITH1 4
IPRG2 5
FREQ 6
SGND 7
VIN 8
TRACK 9
VFB2 10
ITH2 11
PGOOD 12
TOP VIEW
24 SENSE1+
23 PGND
22 BG1
21 SSDIS
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
ORDER PART
NUMBER
LTC3736EGN-1
ELECTRICAL CHARACTERISTICS The denotes specifications that 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 = 0V
VIN < UVLO Threshold
VIN Falling
VIN Rising
500 850
µA
9
20
µA
3
10
µA
1.95 2.25 2.55
V
2.15 2.45 2.75
V
0.45 0.65 0.85
V
Start-Up Current Source
Regulated Feedback Voltage
Output Voltage Line Regulation
RUN/SS = 0V
0°C to 85°C (Note 5)
–40°C to 85°C
2.75V < VIN < 9.8V (Note 5)
0.5
0.7
1
µA
0.591 0.6 0.609
V
0.588 0.6 0.612
V
0.05
0.2
mV/V
37361f
2





 LTC3736-1
LTC3736-1
ELECTRICAL CHARACTERISTICS The denotes specifications that 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
Output Voltage Load Regulation
VFB1,2 Input Current
TRACK Input Current
ITH = 0.9V (Note 5)
ITH = 1.7V
(Note 5)
TRACK = 0.6V
0.12 0.5
%
–0.12 –0.5
%
10
50
nA
10
50
nA
Overvoltage Protect Threshold
Overvoltage Protect Hysteresis
Measured at VFB
0.66 0.68
0.7
V
20
mV
Top Gate (TG) Drive 1, 2 Rise Time
Top Gate (TG) Drive 1, 2 Fall Time
Bottom Gate (BG) Drive 1, 2 Rise Time
Bottom Gate (BG) Drive 1, 2 Fall Time
Maximum Current Sense Voltage
(SENSE+ – SW)(VSENSE(MAX))
Soft-Start Time
Spread Spectrum Oscillator
CL = 3000pF
CL = 3000pF
CL = 3000pF
CL = 3000pF
IPRG = Floating (Note 6)
IPRG = 0V
IPRG = VIN
Time for VFB1 to Ramp from 0.05V to 0.55V
40
ns
40
ns
50
ns
40
ns
110
125
140
mV
70
85
100
mV
185
204
223
mV
0.667 0.833
1
ms
Oscillator Frequency
Spread Spectrum Frequency Range
Spread Spectrum Disabled (SSDIS = VIN)
VFREQ = Floating
VFREQ = 0V
VFREQ = VIN
SSDIS = GND
Minimum Switching Frequency
Maximum Switching Frequency
480
550
600
kHz
260
300
340
kHz
650
750
825
kHz
450
kHz
580
kHz
PGOOD Output
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 –10.0 –7
%
–16 –13.3 –10
%
7
10.0
13
%
10
13.3
16
%
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3736E-1 is guaranteed to meet specified performance
from 0°C to 70°C. Specifications over the –40°C to 85°C operating range
are assured by design, characterization and correlation with statistical
process controls.
Note 3: TJ is calculated from the ambient temperature TA and power
dissipation PD according to the following formula:
TJ = TA + (PD θJA°C/W)
Note 4: Dynamic supply current is higher due to gate charge being
delivered at the switching frequency.
Note 5: The LTC3736-1 is tested in a feedback loop that servos ITH to a
specified voltage and measures the resultant VFB voltage.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as shown in Figure 2.
37361f
3



Recommended third-party LTC3736-1 Datasheet






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