OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

LTC3737EUF#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
1
LTC3737
3737fa
Dual 2-Phase, No R
SENSE
TM
,
DC/DC Controller with
Output Tracking
Figure 1. High Efficiency, 2-Phase, 550kHz Dual Step-Down Converter
■
Sense Resistor Optional
■
Out-of-Phase Controllers Reduce Required
Input Capacitance
■
Programmable Output Voltage Tracking
■
Constant Frequency Current Mode Architecture
■
Wide V
IN
Range: 2.75V to 9.8V
■
Wide V
OUT
Range: 0.6V to V
IN
■
0.6V ±1.5% Reference
■
Low Dropout Operation: 100% Duty Cycle
■
True PLL for Frequency Locking or Adjustment
(Frequency Range 250kHz to 850kHz)
■
Selectable Burst Mode
®
or Pulse Skipping Operation
at Light Loads
■
Internal Soft-Start Circuitry
■
Selectable Maximum Peak Current Sense Threshold
■
Power Good Output Voltage Monitor
■
Output Overvoltage Protection
■
Micropower Shutdown: I
Q
= 9µA
■
Tiny 4mm × 4mm QFN and 24-Lead SSOP Packages
■
One or Two Lithium-Ion Powered Devices
■
Notebook and Palmtop Computers, PDAs
■
Portable Instruments
■
Distributed DC Power Systems
The LTC
®
3737 is a 2-phase dual step-down switching
regulator controller that requires few external compo-
nents. The constant frequency current mode architecture
provides excellent AC and DC load and line regulation.
MOSFET V
DS
sensing eliminates the need for current
sense resistors and improves efficiency. Power loss and
noise due to the ESR of the input capacitance are mini-
mized by operating the two controllers out of phase.
Burst Mode operation provides high efficiency operation
at light loads. 100% duty cycle provides low dropout
operation and extends battery operating time.
Switching frequency can be programmed up to 750kHz,
allowing the use of small surface mount inductors and
capacitors. For noise sensitive applications, the LTC3737
can be externally synchronized from 250kHz to 850kHz.
Other features include a power good output voltage moni-
tor, a tracking input and internal soft-start.
The LTC3737 is available in the low profile thermally
enhanced (4mm × 4mm) QFN package or a 24-lead SSOP
narrow package.
+
+
SW1
V
FB1
I
TH1
PGOOD
SGND
TRACK
I
TH2
V
FB2
SW2
SENSE1
+
PV
IN1
PGATE1
V
IN
PGND
RUN/SS
PGATE2
PV
IN2
SENSE2
+
LTC3737
15k
M1
2.2µH
2.2µH
M2
D1
47µF
10µF
×2
V
IN
2.75V TO
9.8V
V
OUT1
2.5V
V
OUT2
1.8V
47µF
3737 F01
D2
59k
187k
59k
118k
15k
220pF
220pF
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
LOAD CURRENT (mA)
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
1 100 1000 10000
3737 F01b
10
10000
1000
100
10
1
POWER LOSS (mW)
EFFICIENCY
V
OUT
= 1.8V
V
OUT
= 2.5V
V
IN
= 3.3V
TYPICAL POWER LOSS
(V
OUT
= 2.5V)
Efficiency and Power Loss vs Load Current
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode
is a registered trademark of Linear Technology Corporation. No R
SENSE
is a trademark of
Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 5481178, 5731694, 5929620, 6144194,
6580258, 5994885
2
LTC3737
3737fa
24 23 22 21 20 19
7 8 9
TOP VIEW
25
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
10 11 12
6
5
4
3
2
1
13
14
15
16
17
18
I
TH1
IPRG2
PLLLPF
SGND
V
IN
TRACK
PGATE1
PGND
PGATE2
RUN/SS
NC
V
FB1
IPRG1
SENSE1
+
PV
IN1
NC
V
FB2
I
TH2
PGOOD
SENSE2
+
PV
IN2
SW1
(SENSE1
–
)
SW2
(SENSE2
–
)
SYNC/
MODE
Input Supply Voltage (V
IN
), PV
IN1
, PV
IN2
,
SENSE1
+
, SENSE2
+
.................................. –0.3V to 10V
PGATE1, PGATE2, PLLLPF, RUN/SS, SYNC/MODE,
TRACK, IPRG1, IPRG2 Voltages .... –0.3V to (V
IN
+ 0.3V)
V
FB1
, V
FB2
, I
TH1
, I
TH2
Voltages .................. –0.3V to 2.4V
SW1, SW2 Voltages ............ –2V to V
IN
+ 1V or 10V Max
PGOOD ..................................................... –0.3V to 10V
PGATE1, PGATE2 Peak Output Current (<10µs) ......... 1A
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
T
JMAX
= 125°C, θ
JA
= 130°C/W
ORDER PART
NUMBER
LTC3737EGN
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Ambient Temperature Range
QFN Package .................................... –65°C to 125°C
SSOP Package .................................. –65°C to 150°C
Junction Temperature (Note 3) ............................ 125°C
Lead Temperature (Soldering, 10sec)
LTC3737EGN ................................................... 300°C
(Note 1)
ORDER PART
NUMBER
3737
LTC3737EUF
UF PART
MARKING
T
JMAX
= 125°C, θ
JA
= 37°C/W
EXPOSED PAD IS PGND (PIN 25) MUST BE SOLDERED TO PCB
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
SW1
(SENSE1
–
)
SW2
(SENSE2
–
)
GN PACKAGE
24-LEAD (NARROW) PLASTIC SSOP
24
23
22
21
20
19
18
17
16
15
14
13
IPRG1
V
FB1
I
TH1
IPRG2
PLLLPF
SGND
V
IN
TRACK
V
FB2
I
TH2
PGOOD
SENSE1
+
PV
IN1
NC
SYNC/MODE
PGATE1
PGND
PGATE2
RUN/SS
NC
PV
IN2
SENSE2
+
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 4.2V unless otherwise specified.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
Input DC Supply Current (Note 4)
Sleep Mode 220 325 µA
Shutdown RUN/SS = 0V 9 20 µA
UVLO V
IN
< UVLO Threshold –200mV 3 10 µA
Undervoltage Lockout Threshold V
IN
Falling ● 1.95 2.25 2.55 V
V
IN
Rising ● 2.15 2.45 2.75 V
Shutdown Threshold at RUN/SS 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) 0.591 0.6 0.609 V
–40°C to 85°C
● 0.588 0.6 0.612 V
Output Voltage Line Regulation 2.75V < V
IN
< 9.8V (Note 5) 0.05 0.2 mV/V
3
LTC3737
3737fa
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 4.2V unless otherwise specified.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3737E 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: 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
• θ
JA
°C/W)
Note 4: Dynamic supply current is higher due to gate charge being
delivered at the switching frequency.
Note 5: The LTC3737 is tested in a feedback loop that servos I
TH
to a
specified voltage and measures the resultant V
FB
voltage.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as shown in Figure 2.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage Load Regulation I
TH
= 0.9V (Note 5) 0.12 0.5 %
I
TH
= 1.7V –0.12 –0.5 %
V
FB1,2
Input Current (Note 5) 10 50 nA
TRACK Input Current TRACK = 0.6V 10 50 nA
Overvoltage Protect Threshold Measured at V
FB
0.66 0.68 0.7 V
Overvoltage Protect Hysteresis 20 mV
Gate Drive 1, 2 Rise Time C
L
= 3000pF 40 ns
Gate Drive 1, 2 Fall Time C
L
= 3000pF 40 ns
Maximum Current Sense Voltage (∆V
SENSE(MAX)
) IPRG = Floating (Note 6) ● 110 125 140 mV
(SENSE
+
– SW) IPRG = 0V (Note 6) ● 70 85 100 mV
IPRG = V
IN
(Note 6) ● 185 204 223 mV
Soft-Start Time Time for V
FB1
to Ramp from 0.05V to 0.55V 0.667 0.833 1 ms
Oscillator and Phase-Locked Loop
Oscilator Frequency Unsynchronized (SYNC/MODE Not Clocked)
PLLLPF = Floating ● 480 550 600 kHz
PLLLPF = 0V
● 260 300 340 kHz
PLLLPF = V
IN
● 650 750 825 kHz
Phase-Locked Loop Lock Range SYNC/MODE Clocked
Minimum Synchronizable Frequency
● 200 250 kHz
Maximum Synchronizable Frequency ● 850 1150 kHz
Phase Detector Output Current
Sinking f
OSC
> f
SYNC/MODE
–4 µA
Sourcing f
OSC
< f
SYNC/MODE
4 µA
PGOOD Output
PGOOD Voltage Low I
PGOOD
Sinking 1mA 125 mV
PGOOD Trip Level V
FB
with Respect to Set Output Voltage
V
FB
< 0.6V, Ramping Positive –13 –10.0 –7 %
V
FB
< 0.6V, Ramping Negative –16 –13.3 –10 %
V
FB
> 0.6V, Ramping Negative 7 10.0 13 %
V
FB
> 0.6V, Ramping Positive 10 13.3 16 %
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24

LTC3737EUF#TRPBF

Mfr. #:
Buy LTC3737EUF#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 2-Phase Controller w/Tracking
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet