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LTC1709EG-7#PBF

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1
LTC1709-7
The LTC
®
1709-7 is a 2-phase, VID programmable, synchro-
nous step-down switching regulator controller that drives
two all N-channel external power MOSFET stages in a fixed
frequency architecture. The 2-phase controller drives its two
output stages out of phase at frequencies up to 300kHz to
minimize the RMS ripple currents in both input and output
capacitors. The 2-phase technique effectively multiplies the
fundamental frequency by two, improving transient re-
sponse while operating each channel at an optimum fre-
quency for efficiency. Thermal design is also simplified.
An operating mode select pin (FCB) can be used to regu-
late a secondary winding or select among three modes
including Burst Mode
TM
operation for highest efficiency. An
internal differential amplifier provides true remote sensing
of the regulated supply’s positive and negative output ter-
minals as required in high current applications.
The RUN/SS pin provides soft-start and optional timed,
short-circuit shutdown. Current foldback limits MOSFET
dissipation during short-circuit conditions when the
overcurrent latchoff is disabled. OPTI-LOOP compensation
allows the transient response to be optimized for a wide
range of output capacitors and ESR values.
2-Phase, 5-Bit VID,
Current Mode, High Efficiency,
Synchronous Step-Down Switching Regulator
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP and Burst Mode are trademarks of Linear Technology Corporation.
Figure 1. High Current Dual Phase Step-Down Converter
■
Mobile/Desktop Computers
■
Internet Servers
■
Large Memory Arrays
■
DC Power Distribution Systems
■
Output Stages Operate Antiphase Reducing Input
Capacitance Requirements and Power Supply
Induced Noise
■
Dual Input Supply Capability for Load Sharing
■
5-Bit Mobile VID Code: V
OUT
= 0.925V to 2V
■
Current Mode Control Ensures Current Sharing
■
True Remote Sensing Differential Amplifier
■
Power Good Output Indicator
■
OPTI-LOOP
TM
Compensation Minimizes C
OUT
■
Three Operational Modes: PWM, Burst and Cycle Skip
■
Programmable Fixed Frequency: 150kHz to 300kHz
■
±1% Output Voltage Accuracy
■
Wide V
IN
Range: 4V to 36V Operation
■
Adjustable Soft-Start Current Ramping
■
Internal Current Foldback and Short-Circuit Shutdown
■
Overvoltage Soft Latch Eliminates Nuisance Trips
■
Active Voltage Positioning Capable
■
Available in 36-Lead Narrow SSOP Package
170989 F01
TG1
BOOST1
SW1
BG1
PGND
SENSE1
+
SENSE1
–
TG2
BOOST2
SW2
BG2
INTV
CC
SENSE2
+
SENSE2
–
V
IN
RUN/SS
FCB
V
DIFFOUT
I
TH
ATTENIN
ATTENOUT
EAIN
VID0–VID4
V
OS
–
V
OS
+
LTC1709-7
SGND
PGOOD
0.1µF
220pF
5 VID BITS
S
S
3.3k
+
10µF
35V
×4
+
+
C
OUT
1000µF
4V
×2
V
OUT
0.925V TO 2V
40A
1µH
0.002Ω
0.002Ω
V
IN
5V TO 28V
1µH
0.47µF
0.47µF
10µF
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LTC1709-7
ORDER PART
NUMBER
LTC1709EG-7
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
T
JMAX
= 125°C, θ
JA
= 85°C/W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
BIAS
= 5V, V
RUN/SS
= 5V unless otherwise noted.
(Note 1)
Input Supply Voltage (V
IN
).........................36V to –0.3V
Topside Driver Voltages (BOOST1,2).........42V to –0.3V
Switch Voltage (SW1, 2) .............................36V to –5 V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages ...................(1.1)INTV
CC
to –0.3V
EAIN, V
OS
+
, V
OS
–
, EXTV
CC
, INTV
CC
, RUN/SS,
V
BIAS
, ATTENIN, ATTENOUT, PGOOD,
VID0–VID4, Voltages ...............................7V to –0.3V
Boosted Driver Voltage (BOOST-SW) ..........7V to –0.3V
PLLFLTR, PLLIN, V
DIFFOUT
,
FCB Voltages ................................... INTV
CC
to –0.3V
I
TH
Voltage................................................2.7V to –0.3V
Peak Output Current <1µs(TGL1,2, BG1,2)................ 3A
INTV
CC
RMS Output Current................................ 50mA
Operating Ambient Temperature Range
(Note 2) .............................................. –40°C to 85°C
Junction Temperature (Note 3)............................. 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
V
EAIN
Regulated Feedback Voltage I
TH
Voltage = 1.2V (Note 4) ● 0.792 0.800 0.808 V
V
SENSEMAX
Maximum Current Sense Threshold V
SENSE
–
= 5V ● 62 75 88 mV
I
INEAIN
Feedback Current (Note 4) –5 –50 nA
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop, ∆I
TH
Voltage: 1.2V to 0.7V ● 0.1 0.5 %
Measured in Servo Loop, ∆I
TH
Voltage: 1.2V to 2V ● –0.1 –0.5 %
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 3.6V to 30V (Note 4) 0.002 0.02 %/V
V
FCB
Forced Continuous Threshold ● 0.76 0.8 0.84 V
I
FCB
Forced Continuous Current – 0.17 –1 µA
V
BINHIBIT
Burst Inhibit (Constant Frequency) Measured at FCB pin 4.3 4.8 V
Threshold
V
OVL
Output Overvoltage Threshold Measured at V
EAIN
● 0.84 0.86 0.88 V
UVLO Undervoltage Lockout V
IN
Ramping Down 3 3.5 4 V
g
m
Transconductance Amplifier g
m
I
TH
= 1.2V, Sink/Source 5µA (Note 4) 3 mmho
g
mOL
Transconductance Amplifier Gain I
TH
= 1.2V, (g
m
× Z
L
; No Ext Load) (Note 4) 1.5 V/mV
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TOP VIEW
G PACKAGE
36-LEAD PLASTIC SSOP
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
RUNN/SS
SENSE1
+
SENSE1
–
EAIN
PLLFLTR
PLLIN
FCB
I
TH
SGND
V
DIFFOUT
V
OS
–
V
OS
+
SENSE2
–
SENSE2
+
ATTENOUT
ATTENIN
VID0
VID1
NC
TG1
SW1
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
SW2
TG2
PGOOD
V
BIAS
VID4
VID3
VID2
3
LTC1709-7
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
BIAS
= 5V, V
RUN/SS
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Input DC Supply Current (Note 5)
Normal Mode EXTV
CC
Tied to V
OUT
, V
OUT
= 5V 470 µA
Shutdown V
RUN/SS
= 0V 20 40 µA
I
RUN/SS
Soft-Start Charge Current V
RUN/SS
= 1.9V –0.5 –1.2 µA
V
RUN/SS
RUN/SS Pin ON Arming V
RUN/SS
Rising 1.0 1.5 1.9 V
V
RUN/SSLO
RUN/SS Pin Latchoff Arming V
RUN/SS
Rising from 3V 4.1 4.5 V
I
SCL
RUN/SS Discharge Current Soft Short Condition V
EAIN
= 0.5V, V
RUN/SS
= 4.5V 0.5 2 4 µA
I
SDLHO
Shutdown Latch Disable Current V
EAIN
= 0.5V 1.6 5 µA
I
SENSE
Total Sense Pins Source Current Each Channel: V
SENSE1
–
, 2
– = V
SENSE1
+
, 2
+ = 0V –85 –60 µA
DF
MAX
Maximum Duty Factor In Dropout 98 99.5 %
Top Gate Transition Time: (Note 6)
TG1, 2 t
r
Rise Time C
LOAD
= 3300pF 30 90 ns
TG1, 2 t
f
Fall Time C
LOAD
= 3300pF 40 90 ns
Bottom Gate Transition Time: (Note 6)
BG1, 2 t
r
Rise Time C
LOAD
= 3300pF 30 90 ns
BG1, 2 t
f
Fall Time C
LOAD
= 3300pF 20 90 ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay C
LOAD
= 3300pF Each Driver (Note 6) 90 ns
Synchronous Switch-On Delay Time
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay C
LOAD
= 3300pF Each Driver (Note 6) 90 ns
Top Switch-On Delay Time
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 7) 180 ns
Internal V
CC
Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 30V, V
EXTVCC
= 4V 4.8 5.0 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0 to 20mA, V
EXTVCC
= 4V 0.2 1.0 %
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 5V 80 160 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive ● 4.5 4.7 V
V
LDOHYS
EXTV
CC
Switchover Hysteresis I
CC
= 20mA, EXTV
CC
Ramping Negative 0.2 V
VID Parameters
V
BIAS
Operating Supply Voltage Range 2.7 5.5 V
R
ATTEN
Resistance Between ATTENIN 10 kΩ
and ATTENOUT Pins
ATTEN
ERR
Resistive Divider Error ● –0.25 –0.25 %
R
PULLUP
VID0 to VID4 Pull-Up Resistance (Note 8) 40 kΩ
VID
THLOW
VID0 to VID4 Logic Threshold Low 0.4 V
VID
THHIGH
VID0 to VID4 Logic Threshold High 1.6 V
VID
LEAK
VID0 to VID4 Leakage V
BIAS
< VID0–VID4 < 7V 1 µA
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 190 220 250 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 120 140 160 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 280 310 360 kHz
R
PLLIN
PLLIN
Input Resistance 50 kΩ
I
PLLFLTR
Phase Detector Output Current
Sinking Capability f
PLLIN
< f
OSC
–15 µA
Sourcing Capability f
PLLIN
> f
OSC
15 µA
R
RELPHS
Controller 2-Controller 1 Phase 180 Deg
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LTC1709EG-7#PBF

Mfr. #:
Buy LTC1709EG-7#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Hi Pwr Polyphase Dc/DC Controller
Lifecycle:
New from this manufacturer.
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