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LTC1702IGN#TRPBF

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LTC1702
1702fa
Dual 550kHz Synchronous
2-Phase Switching Regulator Controller
The LTC
®
1702 is a dual switching regulator controller opti-
mized for high efficiency with low input voltages. It includes
two complete, on-chip, independent switching regulator
controllers each designed to drive a pair of external N-channel
MOSFET devices in a voltage mode feedback, synchronous
buck configuration. The LTC1702 uses a constant-frequency,
true PWM design switching at 550kHz, minimizing external
component size and cost and maximizing load transient
performance. The synchronous buck architecture automati-
cally shifts to discontinuous and then to Burst Mode
TM
operation as the output load decreases, ensuring maximum
efficiency over a wide range of load currents.
The LTC1702 features an onboard reference trimmed to
0.5% and can provide better than 1% regulation at the
converter outputs. Open-drain logic outputs indicate whether
either output has risen to within 5% of the final output voltage
and an optional latching FAULT mode protects the load if the
output rises 15% above the intended voltage. Each channel
can be enabled independently; with both channels disabled,
the LTC1702 shuts down and supply current drops below
100µA.
■
Two Independent Controllers in One Package
■
Two Sides Run Out-of-Phase to Minimize C
IN
■
All N-Channel External MOSFET Architecture
■
No External Current Sense Resistors
■
Excellent Output Regulation: 1% Total Output
Accuracy
■
550kHz Switching Frequency Minimizes External
Component Size
■
1A to 25A Output Current per Channel
■
High Efficiency over Wide Load Current Range
■
Quiescent Current Drops Below 100µA in Shutdown
■
Small 24-Pin Narrow SSOP Package
■
Microprocessor Core and I/O Supplies
■
Multiple Logic Supply Generator
■
Distributed Power Applications
■
High Efficiency Power Conversion
Dual Output High Power 3.3V/2.5V Logic Supply
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
LTC1702
PV
CC
BOOST1
BG1
TG1
SW1
I
MAX1
PGOOD1
FCB
RUN/SS
COMP1
SGND
FB1
I
MAX2
BOOST2
BG2
TG2
SW2
PGND
PGOOD2
FAULT
RUN/SS2
COMP2
FB2
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
1µF
10Ω
1µF
1µF
27k
27k
1.6k
68k
1702 TA01
V
IN
1.2k
10k
1%
C
OUT1
180µF
×4
820pF
27pF
680pF
47k
1µF
V
OUT1
2.5V
AT 15A
1µF
4.75k
1%
Q2Q1
Q4Q3
D3
D2
C
OUT1
, C
OUT2
: PANASONIC EEFUE0G181R
C
IN
: KEMET TS10X337M010AS
D1, D2: MOTOROLA MBR0520LT1
D3, D4: MOTOROLA MBRS320T3
L1, L2: SUMIDA CEP125-1R0
Q1 TO Q8: FAIRCHILD FDS6670A
D1
PWRGD1
L1
1µH
+
10µF
10µF
1µF
V
IN
= 5V ±10%
1µF
C
IN
330µF
×3
+
Q7
Q5
Q8
Q6
D4
680pF
27pF
3300pF
15.8k
1%
4.99k
1%
10k
L2
1µH
C
OUT2
180µF
×4
1µF
V
OUT2
3.3V/15A
PWRGD2
FAULT
+
V
IN
10k
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode
is a registered trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 5481178,
5847554, 6304066, 6307356, 6580258.
2
LTC1702
1702fa
ABSOLUTE MAXIMUM RATINGS
W
WW
U
(Note 1)
Supply Voltage
V
CC
........................................................................ 7V
BOOST
n...............................................................
15V
BOOST
n
– SW
n
.................................................... 7V
Input Voltage
SW
n
.......................................................... – 1V to 8V
All Other Inputs ......................... – 0.3V to V
CC
+ 0.3V
Peak Output Current < 10µs
TG
n
, BG
n
............................................................... 5A
Operating Temperature Range
LTC1702C ............................................... 0°C to 70°C
LTC1702I........................................... –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
PACKAGE/ORDER INFORMATION
W
U
U
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V unless otherwise specified. (Note 3)
T
JMAX
= 125°C, θ
JA
= 100°C/ W
ORDER PART NUMBER
Consult LTC Marketing for parts specified with wider operating temperature ranges.
LTC1702CGN
LTC1702IGN
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
24
23
22
21
20
19
18
17
16
15
14
13
PV
CC
BOOST1
BG1
TG1
SW1
I
MAX1
PGOOD1
FCB
RUN/SS1
COMP1
SGND
FB1
I
MAX2
BOOST2
BG2
TG2
SW2
PGND
PGOOD2
FAULT
RUN/SS2
COMP2
FB2
V
CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
V
CC
V
CC
Supply Voltage ● 37V
PV
CC
PV
CC
Supply Voltage (Note 2) ● 37V
BV
CC
BOOST Pin Voltage V
BOOST
– V
SW
(Note 2) ● 2.7 7 V
I
CC
V
CC
Supply Current Test Circuit 1, C
L
= 0pF ● 2.2 8 mA
RUN/SS1 = RUN/SS2 = 0V (Note 5)
● 30 100 µA
IPV
CC
PV
CC
Supply Current Test Circuit 1, C
L
= 0pF (Note 4) ● 2.2 6 mA
RUN/SS1 = RUN/SS2 = 0V (Note 5)
● 6 100 µA
I
BOOST
BOOST Pin Current Test Circuit 1, C
L
= 0pF (Note 4) ● 1.3 3 mA
RUN/SS1 = RUN/SS2 = 0V
● 0.1 10 µA
V
FB
Feedback Voltage Test Circuit 1, C
L
= 0pF, LTC1702C ● 0.792 0.800 0.808 V
Test Circuit 1, C
L
= 0pF, LTC1702I ● 0.790 0.800 0.810 V
∆V
FB
Feedback Voltage Line Regulation V
CC
= 3V to 7V ● ±0.005 ±0.05 %/V
I
FB
Feedback Current ● ±0.001 ±1 µA
∆V
OUT
Output Voltage Load Regulation (Note 6) ● 0.1 ±0.2 %
V
FCB
FCB Threshold ● 0.75 0.8 0.85 V
∆V
FCB
FCB Feedback Hysteresis 20 mV
I
FCB
FCB Pin Current ● ±0.001 ±1 µA
V
RUN
RUN/SS Pin RUN Threshold ● 0.45 0.55 0.65 V
I
SS
Soft-Start Source Current RUN/SS
n
= 0V –2 –3.5 –6 µA
3
LTC1702
1702fa
ELECTRICAL CHARACTERISTICS
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: PV
CC
and BV
CC
(V
BOOST
– V
SW
) must be greater than V
GS(ON)
of
the external MOSFETs used to ensure proper operation.
Note 3: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 4: Supply current in normal operation is dominated by the current
needed to charge and discharge the external MOSFET gates. This current
will vary with supply voltage and the external MOSFETs used.
Note 5: Supply current in shutdown is dominated by external MOSFET
leakage and may be significantly higher than the quiescent current drawn
by the LTC1702, especially at elevated temperature.
Note 6: This parameter is guaranteed by correlation and is not tested
directly.
Note 7: Rise and fall times are measured using 10% and 90% levels. Delay
and nonoverlap times are measured using 50% levels.
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V unless otherwise specified. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Switching Characteristics
f
OSC
Oscillator Frequency Test Circuit 1, C
L
= 0pF ● 475 550 750 kHz
Φ
OSC2
Converter 2 Oscillator Phase Relative to Converter 1 (Note 6) 180 DEG
DC
MIN1
Minimum Duty Cycle V
FB
< V
MAX
● 710 %
DC
MIN2
Minimum Duty Cycle V
FB
> V
MAX
● 0%
DC
MAX
Maximum Duty Cycle ● 87 90 93 %
t
NOV
Driver Nonoverlap Test Circuit 1, C
L
= 2000pF (Note 7) ● 40 100 ns
t
r
, t
f
Driver Rise/Fall Time Test Circuit 1, C
L
= 2000pF (Note 7) ● 12 80 ns
Feedback Amplifier
A
VFB
FB DC Gain ● 74 85 dB
GBW FB Gain Bandwidth 25 MHz
I
ERR
FB Sink/Source Current ● ±3 ±10 mA
V
MIN
MIN Comparator Threshold ● 760 785 mV
V
MAX
MAX Comparator Threshold ● 815 840 mV
Current Limit Loop
A
VILIM
I
LIM
Gain 40 dB
I
IMAX
I
MAX
Source Current I
MAX
= 0V, LTC1702C ● –7 –10 –13 µA
I
MAX
= 0V, LTC1702I ● –7 –10 –14 µA
Status Outputs
V
PGOOD
PGOOD Trip Point V
FB
Relative to Regulated V
OUT
● –10 –5 –2 %
V
OLPG
PGOOD Output Low Voltage PGOOD = 1mA ● 0.03 0.1 V
I
PGOOD
PGOOD Output Leakage ● ±0.1 ±1 µA
t
PGOOD
PGOOD Delay Time V
FB
< V
PGOOD
to PGOOD (Note 7) 100 µs
V
FAULT
FAULT Trip Point V
FB
Relative to Regulated V
OUT
● +10 +15 +20 %
V
OLF
FAULT Output Low Voltage I
FAULT
= 1mA ● 0.03 0.1 V
I
FAULT
FAULT Output Current V
FAULT
= 0V – 10 µA
t
FAULT
FAULT Delay Time V
FB
> V
FAULT
to FAULT (Note 7) 25 µs
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LTC1702IGN#TRPBF

Mfr. #:
Buy LTC1702IGN#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 2x 550kHz Sync 2-PhSw Reg Cntr
Lifecycle:
New from this manufacturer.
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