FEATURES
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LTC3722-1/LTC3722-2
Synchronous Dual Mode
Phase Modulated
Full Bridge Controllers
DESCRIPTION
The
LTC
®
3722-1/LTC3722-2
phase-shift PWM controllers
provide all of the control and protection functions neces-
sary to implement a high efficiency, zero voltage switched
(ZVS), full bridge power converter. Adaptive ZVS circuitry
delays the turn-on signals for each MOSFET independent
of internal and external component tolerances. Manual
delay set mode enables secondary side control operation
or direct control of switch turn-on delays.
The LTC3722-1/LTC3722-2 feature adjustable synchron-
ous rectifier timing for optimal efficiency. A UVLO program
input provides accurate system turn-on and turn-off
voltages. The LTC3722-1 features peak current mode
control with programmable slope compensation and
leading edge blanking, while the LTC3722-2 employs
voltage mode control.
The LTC3722-1/LTC3722-2 feature extremely low operating
and start-up currents. Both devices include a full range of
protection features and are available in the 24-pin surface
mount GN package.
All registered trademarks and trademarks are the property of their respective owners.
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Adaptive or Manual Delay Control for Zero Voltage
Switching Operation
Adjustable Synchronous Rectification Timing for
Highest Efficiency
Adjustable Maximum ZVS Delay
Adjustable System Undervoltage Lockout Hysteresis
Programmable Leading Edge Blanking
Very Low Start-Up and Quiescent Currents
Current Mode (LTC3722-1) or Voltage Mode
(LTC3722-2) Operation
Programmable Slope Compensation
V
CC
UVLO and 25mA Shunt Regulator
50mA Output Drivers
Soft-Start, Cycle-by-Cycle Current Limiting and
Hiccup Mode Short-Circuit Protection
5V, 15mA Low Dropout Regulator
24-Pin Surface Mount GN Package
APPLICATIONS
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Telecommunications, Infrastructure Power Systems
Distributed Power Architectures
Server Power Supplies
TYPICAL APPLICATION
V
IN
36V TO
72V
C
IN
R1
U1
MA
T1
LTC3722
L1
L2
MB
RCS
T2
C1
U1, U2: LTC4440 GATE DRIVER
U3: LTC3901 GATE DRIVER
U3
MF
MD
V
OUT
12V
C
OUT
MC
U2
12V
OUT
, 240W Converter Efficiency
95
36V
IN
90
EFFICIENCY (%)
48V
IN
72V
IN
85
ME
80
75
0
2
4
6
8 10 12 14 16 18 20
CURRENT (A)
372212 TA01b
372212 TA01a
Rev C
Document Feedback
For more information
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1
LTC3722-1/LTC3722-2
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
CC
to GND (Low Impedance Source) ........ –0.3V to 10V
(Chip Self Regulates at 10.3V)
UVLO to GND ..............................................–0.3V to V
CC
All Other Pins to GND
(Low Impedance Source) .......................... –0.3V to 5.5V
V
CC
(Current Fed) ...................................................25mA
V
REF
Output Current ................................. Self Regulated
Outputs (A, B, C, D, E, F) Current ....................... ±100mA
Operating Junction Temperature Range
(Note 6).................................................. –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
PIN CONFIGURATION
LTC3722-1
TOP VIEW
SYNC
DPRG
CS
COMP
RLEB
FB
SS
NC
PDLY
1
2
3
4
5
6
7
8
9
24 C
T
23 GND
22 PGND
21 OUTA
20 OUTB
19 OUTC
18 V
CC
17 OUTD
16 OUTE
15 OUTF
14 V
REF
13 SPRG
SYNC
RAMP
CS
COMP
DPRG
FB
SS
NC
PDLY
1
2
3
4
5
6
7
8
9
LTC3722-2
TOP VIEW
24 C
T
23 GND
22 PGND
21 OUTA
20 OUTB
19 OUTC
18 V
CC
17 OUTD
16 OUTE
15 OUTF
14 V
REF
13 SPRG
SBUS 10
ADLY 11
UVLO 12
SBUS 10
ADLY 11
UVLO 12
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3722EGN-1#PBF
LTC3722EGN-2#PBF
LTC3722IGN-1#PBF
LTC3722IGN-2#PBF
LTC3722HGN-1#PBF
TAPE AND REEL
LTC3722EGN-1#TRPBF
LTC3722EGN-2#TRPBF
LTC3722IGN-1#TRPBF
LTC3722IGN-2#TRPBF
LTC3722HGN-1#TRPBF
PART MARKING
LTC3722EGN-1
LTC3722EGN-2
LTC3722IGN-1
LTC3722IGN-2
LTC3722HGN-1
PACKAGE DESCRIPTION
24-Lead Plastic SSOP
24-Lead Plastic SSOP
24-Lead Plastic SSOP
24-Lead Plastic SSOP
24-Lead Plastic SSOP
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 150°C
Consult ADI Marketing for parts specified with wider operating temperature ranges.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
Rev C
2
For more information
www.analog.com
LTC3722-1/LTC3722-2
ELECTRICAL CHARACTERISTICS
SYMBOL
Input Supply
V
CCUV
V
CCHY
I
CCST
I
CCRN
V
SHUNT
R
SHUNT
SUVLO
SHYST
Delay Blocks
DTHR
DHYS
DTMO
DFXT
DFTM
I
CS
I
SLP
DC
MAX
DC
MIN
Oscillator
OSCI
OSCT
OSCV
OSYT
OSYW
OSYR
Error Amplifier
V
FB
FBI
A
VOL
IIB
V
OH
V
OL
I
SOURCE
I
SINK
FB Input Voltage
FB Input Range
Open-Loop Gain
Input Bias Current
Output High
Output Low
Output Source Current
Output Sink Current
COMP = 2.5V (Note 4)
Measured on FB (Note 5)
COMP = 1V to 3V (Note 4)
COMP = 2.5V (Note 4)
Load on COMP = –100µA
Load on COMP = 100µA
COMP = 2.5V
COMP = 2.5V
400
2
4.7
1.172
–0.3
70
90
5
4.92
0.18
800
5
0.4
20
1.204
1.236
2.5
V
V
dB
nA
V
V
µA
mA
Rev C
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9.5V, C
T
= 270pF R
DPRG
= 60.4k, R
SPRG
= 100k, unless
,
otherwise noted (Note 6).
PARAMETER
V
CC
Under Voltage Lockout
V
CC
UVLO Hysteresis
Start-Up Current
CONDITIONS
Measured on V
CC
Measured on V
CC
V
CC
= V
UVLO
– 0.3V
LTC3722E-1/LTC3722I-1/LTC3722E-2/LTC3722I-2
LTC3722H-1
No Load on Outputs
Current into V
CC
= 10mA
Current into V
CC
= 10mA to 17mA
Measured on UVLO Pin, 10mA into V
CC
Current Flows Out of UVLO Pin
SBUS = 1.5V
SBUS = 2.25V
SBUS = 1.5V, ADLY/PDLY = 1.7V
R
DPRG
= 60.4K
Measured on SBUS
SBUS = V
REF
, ADLY, PDLY = 1V
CS = 1V, COMP = 0V, C
T
= 4V,
LTC3722-1 Only
Measured on CS, C
T
= 1V
C
T
= 2.25V
COMP = 4.5V
COMP = 0V
T
A
= 25°C, C
T
= 270pF
V
CC
= 6.5V to 9.5V
Measured on C
T
Measured on SYNC
Measured at Outputs (Note 2)
Measured at Outputs (Note 2)
1.6
l
l
l
l
l
l
l
MIN
TYP
10.25
MAX
10.5
UNITS
V
V
3.8
4.2
145
145
5
10.3
1.1
230
250
8
10.8
3.5
5.2
11.5
1.6
2.4
µA
µA
mA
V
Ω
V
µA
V
V
mA
ns
V
ns
mA
µA
µA
%
Operating Current
Shunt Regulator Voltage
Shunt Resistance
System UVLO Threshold
System UVLO Hysteresis Current
Delay Pin Threshold
ADLY and PDLY
Delay Hysteresis Current
ADLY and PDLY
Delay Timeout
Fixed Delay Threshold
Fixed Delay Time
CS Discharge Current
Slope Compensation Current
Maximum Phase Shift
Minimum Phase Shift
Initial Accuracy
Total Variation
C
T
Ramp Amplitude
SYNC Threshold
Minimum SYNC Pulse Width
SYNC Frequency Range
4.8
8.5
1.4
2.1
5.0
10
1.5
2.25
1.3
100
4
70
50
30
68
Phase Modulator
95
98.5
0
0.5
275
285
2.2
%
kHz
kHz
V
V
ns
kHz
225
215
250
250
2.5
1.9
75
1000
For more information
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3
LTC3722-1/LTC3722-2
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
Reference
V
REF
REFLD
REFLN
REFTV
REFSC
Outputs
OUTH(x)
OUTL(x)
R
HI(x)
R
LO(x)
t
r(x)
t
f(x)
SDEL
CLPP
Output High Voltage
Output Low Voltage
Pull-Up Resistance
Pull-Down Resistance
Rise Time
Fall Time
SYNC Driver Turn-0ff Delay
Pulse by Pulse Current Limit Threshold
I
OUT(x)
= –50mA
I
OUT(x)
= 50mA
I
OUT(x)
= –50mA to –10mA
I
OUT(x)
= –50mA to –10mA
C
OUT(x)
= 50pF (Note 8)
C
OUT(x)
= 50pF (Note 8)
R
SPRG
= 100k
Measured on CS
LTC3722E-1/LTC3722I-1/LTC3722E-2/LTC3722I-2
LTC3722H-1
Measured on CS
100mV Overdrive on CS (Notes 3, 7)
SS = 2.5V
Measured on SS
Measured on SS
7
0.7
4.5
7.9
8.4
0.6
22
12
5
5
180
1
30
20
15
15
V
V
Ω
Ω
ns
ns
ns
Initial Accuracy
Load Regulation
Line Regulation
Total Variation
Short-Circuit Current
T
A
= 25°C, Measured on V
REF
Load on V
REF
= 100µA to 5mA
V
CC
= 6.5V to 9.5V
Line, Load
V
REF
Shorted to GND
l
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9.5V, C
T
= 270pF R
DPRG
= 60.4k, R
SPRG
= 100k, unless
,
otherwise noted (Note 6).
CONDITIONS
MIN
4.925
TYP
5.00
2
0.9
4.900
18
5.000
30
MAX
5.075
15
10
5.100
45
UNITS
V
mV
mV
V
mA
Current Limit and Shutdown
270
270
0.55
300
300
0.65
80
12
0.4
3.9
17
0.1
3.5
330
340
0.73
mV
mV
V
ns
µA
V
V
CLSD
CLDEL
SSI
SSR
FLT
Shutdown Current Limit Threshold
Current Limit Delay to Output
Soft-Start Current
Soft-Start Reset Threshold
Fault Reset Threshold
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:
Sync amplitude = 5V
P-P
, pulse width = 75ns. Verify output (A-F)
frequency = one-half sync frequency.
Note 3:
Includes leading edge blanking delay, R
LEB
= 20k.
Note 4:
FB is driven by a servo-loop amplifier to control V
COMP
for these
tests.
Note 5:
Set FB to –0.3V, 2.5V and insure that COMP does not phase invert.
Note 6:
The LTC3722 is tested under pulsed load condition such that
T
J
≈ T
A
. The LTC3722E-1/LTC3722E-2 are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to
85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3722I-1/LTC3722I-2 are guaranteed over the –40°C to 85°C operating
junction temperature range and the LTC3722H-1 is guaranteed over the
–40°C to 150°C operating junction temperature range.
High junction temperatures degrade operating lifetimes; operating lifetime
is derated for junction temperatures greater than 125°C. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors.
Note 7:
Guaranteed by design, not tested in production.
Note 8:
Rise time is measured from the 10% to 90% points of the rising
edge of the driver output signal. Fall time is measured from the 90% to
10% points of the falling edge of the driver output signal.
Rev C
4
For more information
www.analog.com
LTC3722-1/LTC3722-2
TYPICAL PERFORMANCE CHARACTERISTICS
200
Start-Up I
CC
vs V
CC
T
A
= 25°C
10.50
V
CC
vs I
SHUNT
T
A
= 25°C
260
Oscillator Frequency
vs Temperature
C
T
= 270pF
150
10.25
FREQUENCY (kHz)
0
10
30
20
I
SHUNT
(mA)
40
50
372212 G02
250
I
CC
(µA)
100
V
CC
(V)
10.00
240
50
9.75
0
0
2
4
V
CC
(V)
6
8
10
372212 G01
9.50
230
–50 –30 –10 10 30 50 70 90 110 130 150
TEMPERATURE (°C)
372212 G03
350
300
250
BLANK TIME (ns)
Leading Edge Blanking Time
vs R
LEB
T
A
= 25°C
5.05
V
REF
vs I
REF
5.01
T
A
= 25°C
T
A
= 85°C
V
REF
vs Temperature
5.00
5.00
4.99
V
REF
(V)
150
100
50
0
4.90
T
A
= –40°C
4.85
V
REF
(V)
0
5
10
15 20
25
I
REF
(mA)
30
35
40
372212 G05
200
4.95
4.98
4.97
0 10 20 30 40 50 60
R
LEB
(k)
70 80 90 100
372212 G04
4.80
4.96
–50 –30 –10 10 30 50 70 90 110 130 150
TEMPERATURE (°C)
372212 G06
Error Amplifier Gain/Phase
100
80
60
40
20
0
–180
–270
–360
10
100
1k
10k 100k
FREQUENCY (Hz)
1M
10M
372212 G07
Start-Up I
CC
vs Temperature
190
180
170
160
I
CC
(µA)
150
140
130
120
110
100
–60
–30
0
30
60
90
TEMPERATURE (°C)
120
150
HYSTERESIS CURRENT (mA)
Delay Hysteresis Current
vs Temperature
1.302
1.300
1.298
1.296
1.294
1.292
1.290
1.288
1.286
1.284
1.282
1.280
–60
–30
60
30
0
90
TEMPERATURE (°C)
120
150
SBUS = 1.5V
T
A
= 25°C
PHASE (DEG)
GAIN (dB)
372212 G08
372212 G09
Rev C
For more information
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5
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