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LTC3700EMS#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
1
LTC3700
3700f
LOAD CURRENT (mA)
1
EFFICIENCY (%)
90
86
82
78
74
70
66
62
58
54
50
10 100 1000
3700 F01a
V
OUT
= 1.8V
R
SENSE
= 0.068Ω
V
IN
= 3.3V
V
IN
= 5V
V
IN
= 4.2V
Constant Frequency
Step-Down DC/DC Controller
with LDO Regulator
The LTC
®
3700 is a constant frequency current mode step-
down (buck) DC/DC controller with excellent AC and DC
load and line regulation. The on-chip 150mA low dropout
(LDO) linear regulator can be powered from the buck
controller’s input supply, its own independent input supply
or the buck regulator’s output. The buck controller incor-
porates an undervoltage lockout feature that shuts down the
controller when the input voltage falls below 2.1V.
The buck regulator provides a ±2.5% output voltage accu-
racy. It consumes only 210µA of quiescent current in nor-
mal operation with the LDO consuming an additional 50µA.
In shutdown, a mere 10µA (combined) is consumed.
For applications where efficiency is a prime consideration,
the buck controller is configured for Burst Mode operation
which enhances efficiency at low output current. To fur-
ther maximize the life of a battery source, the external
P-channel MOSFET is turned on continuously in dropout
(100% duty cycle). High constant operating frequency of
550kHz allows the use of a small external inductor.
The LDO is protected by both current limit and thermal
shutdown circuits.
The LTC3700 is available in a tiny 10-pin MSOP.
■
Notebook Computers
■
Portable Instruments
■
One or Two Li-Ion Battery-Powered Applications
■
Dual Output Regulator in Tiny 10-Pin MSOP
■
High Efficiency: Up to 94%
■
Wide V
IN
Range: 2.65V to 9.8V
■
Constant Frequency 550kHz Operation
■
150mA LDO Regulator with Current Limit and
Thermal Shutdown Protection
■
High Output Currents Easily Achieved
■
Burst Mode
®
Operation at Light Load
■
Low Dropout: 100% Duty Cycle
■
Current Mode Operation for Excellent Line and Load
Transient Response
■
0.8V Reference Allows Low Output Voltages
■
Low Quiescent Current: 260µA Total
■
Shutdown Mode Draws Only 10µA Supply Current
■
Common Power Good Output for Both Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
+
SENSE
–
LTC3700
PGATE
V
FB
LDO
V
FB2
PGOOD
V
IN
V
IN2
I
TH
/RUN GND
M1
L1
10µH
C2
47µF
6V
100k
80.6k
D1
10k
169k
C4
2.2µF
16V
78.7k
V
OUT2
2.5V AT
150mA
3700 F01
V
IN2
3.3V
V
OUT1
1.8V
AT 1A
C1, C3: TAIYO YUDEN EMK325BJ106MNT
C2: SANYO POSCAP 6TPA47M
C4: MURATA GRM42-6X7R225K016AL
D1: MOTOROLA MBRM120T3
L1: COILTRONICS UP1B-100
M1: Si3443DV
R1: DALE 0.25W
V
IN1
5V
C3
10µF
10V
C1
10µF
10V
R1
0.068Ω
220pF
Figure 1. High Efficiency 5V to 1.8V/1A Buck with 3.3V to 2.5V/150mA LDO
Buck Efficiency vs Load Current
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LTC3700
3700f
ABSOLUTE MAXIMUM RATINGS
W
WW
U
(Note 1)
Buck Input Supply Voltage (V
IN
)................–0.3V to 10V
SENSE
–
, PGATE Voltages............. –0.3V to (V
IN
+ 0.3V)
V
FB
, I
TH
/RUN Voltages ..............................–0.3V to 2.4V
PGATE Peak Output Current (<10µs) ....................... 1A
LDO Input Supply Voltage (V
IN2
) .................–0.3V to 6V
LDO, V
FB2
Voltages..................... –0.3V to (V
IN2
+ 0.3V)
PGOOD Voltage .........................................–0.3V to 10V
LDO Peak Output Current (< 10µs)..................... 500mA
Storage Ambient Temperature Range ... –65°C to 150°C
Operating Temperature Range (Note 2) ... –40°C to 85°C
Junction Temperature (Note 3).............................150°C
Lead Temperature (Soldering, 10 sec)..................300°C
PACKAGE/ORDER INFORMATION
W
U
U
T
JMAX
= 150°C, θ
JA
= 230°C/ W
MS PART MARKING
ORDER PART
NUMBER
LTC3700EMS
LTXN
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= V
IN2
= 4.2V unless otherwise specified. (Note 2)
1
2
3
4
5
V
IN2
LDO
V
FB2
PGOOD
GND
10
9
8
7
6
I
TH
/RUN
V
FB
SENSE
–
V
IN
PGATE
TOP VIEW
MS PACKAGE
10-LEAD PLASTIC MSOP
PARAMETER CONDITIONS MIN TYP MAX UNITS
Buck DC/DC Controller
Input DC Supply Current Typicals at V
IN
= 4.2V (Note 4)
Normal Operation 2.65V ≤ V
IN
≤ 9.8V 210 340 µA
Sleep Mode 2.65V ≤ V
IN
≤ 9.8V 200 330 µA
Shutdown 2.65V ≤ V
IN
≤ 9.8V, V
ITH
/RUN = 0V 10 30 µA
UVLO V
IN
< UVLO Threshold 10 30 µA
Undervoltage Lockout Threshold V
IN
Falling ● 1.90 2.10 2.60 V
V
IN
Rising ● 2.00 2.20 2.65 V
Shutdown Threshold (at I
TH
/RUN) ● 0.15 0.30 0.45 V
Start-Up Current Source V
ITH
/RUN = 0V 0.25 0.5 0.85 µA
Regulated Feedback Voltage (Note 5), 0°C to 70°C ● 0.780 0.800 0.820 V
(Note 5), –40°C to 85°C
● 0.770 0.800 0.830 V
Output Voltage Line Regulation 2.65V ≤ V
IN
≤ 9.8V (Note 5) 0.1 mV/V
Output Voltage Load Regulation I
TH
/RUN Sinking 5µA (Note 5) 4 mV/µA
I
TH
/RUN Sourcing 5µA (Note 5) 4 mV/µA
V
FB
Input Current (Note 5) 10 50 nA
Overvoltage Protect Threshold Measured at V
FB
0.820 0.860 0.910 V
Overvoltage Protect Hysteresis 20 mV
Oscillator Frequency V
FB
= 0.8V 500 550 650 kHz
V
FB
= 0V 110 kHz
Gate Drive Rise Time C
LOAD
= 3000pF 40 ns
Gate Drive Fall Time C
LOAD
= 3000pF 40 ns
Peak Current Sense Voltage (Note 6) 120 mV
Peak Current Sense Voltage in Burst Mode 30 mV
3
LTC3700
3700f
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3700 is guaranteed to meet specifications from␣ 0°C␣ to
70°C. Specifications over the –40°C to 85°C operating temperature 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 the gate charge being
delivered at the switching frequency.
Note 5: The LTC3700 is tested in a feedback loop that servos V
FB
to the
output of the error amplifier.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as given in Figure 2.
Note 7: Guaranteed by design; not tested in production.
Note 8: PGOOD values are expressed as a percentage difference from the
respective “Regulated Feedback Voltage” as given in the table.
PARAMETER CONDITIONS MIN TYP MAX UNITS
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= V
IN2
= 4.2V unless otherwise specified. (Note 2)
LDO Regulator
V
IN2
Input Voltage 2.4 6 V
Input DC Supply Current Typicals at V
IN2
= 4.2V
Normal Operation with Buck Enabled 2.4V ≤ V
IN2
≤ 6V 50 100 µA
Normal Operation with Buck Undervoltage 2.4V ≤ V
IN2
≤ 6V 100 150 µA
Shutdown with Buck Enabled 2.4V ≤ V
IN2
≤ 6V, V
ITH/RUN
= 0V 0 1 µA
Shutdown with Buck Undervoltage 2.4V ≤ V
IN2
≤ 6V, V
ITH/RUN
= 0V 8 24 µA
Regulated Feedback Voltage 0°C ≤ T
A
≤ 70°C, I
LDO
= 1mA ● 0.780 0.800 0.830 V
–40°C ≤ T
A
≤ 85°C, I
LDO
= 1mA ● 0.765 0.800 0.835 V
Output Voltage Line Regulation (Unity-Gain Feedback)
With Buck Enabled 2.65V ≤ V
IN
≤ 9.8V 0.05 mV/V
With Buck Enabled 2.4V ≤ V
IN2
≤ 6V, I
LDO
= 1mA 4 mV/V
With Buck Undervoltage 2.4V ≤ V
IN2
≤ 6V, I
LDO
= 1mA 4 mV/V
Output Voltage Load Regulation 1mA ≤ I
LOAD
≤ 150mA 0.06 0.12 mV/mA
V
FB2
Input Current 010 nA
LDO Short-Circuit Current V
LDO
= 0V 150 200 mA
LDO Dropout V
IN2
= 3.3V, I
LDO
= 150mA 270 mV
V
IN2
= 6V, I
LDO
= 150mA 170 mV
Overtemperature Trip Point (Note 7) 150 °C
Overtemperature Hysteresis (Note 7) 5 °C
PGOOD
Feedback Voltage PGOOD Threshold (Note 8)
PGOOD High-to-Low V
FB
or V
FB2
Falling –12 –7.5 %
V
FB
or V
FB2
Rising 7.5 12 %
PGOOD Low-to-High V
FB
or V
FB2
Rising –10 –5.0 %
V
FB
or V
FB2
Falling 5.0 10 %
PGOOD On-Resistance V
ITH/RUN
= 0V, V
IN
= V
IN2
= 4.2V, V
PGOOD
= 100mV 135 180 Ω
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LTC3700EMS#PBF

Mfr. #:
Buy LTC3700EMS#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Const Freq Buck DC/DC Cntr w/ LDO Reg
Lifecycle:
New from this manufacturer.
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