Final Electrical Specifications
LTC3722-1/LTC3722-2
Synchronous Dual Mode
Phase Modulated
Full Bridge Controllers
FEATURES
s
s
DESCRIPTIO
February 2003
s
s
s
s
s
s
s
s
s
s
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 and
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
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 synchro-
nous rectifier timing for optimal efficiency. A UVLO pro-
gram input provides accurate system turn-on and turn-off
voltages. The LTC3722-1 features peak current mode
control with programmable slope compensation and lead-
ing edge blanking, while the LTC3722-2 employs voltage
mode control with voltage feedforward capability.
The LTC3722-1/LTC3722-2 feature extremely low operat-
ing and start-up currents. Both devices include a full range
of protection features and are available in the 24-pin
surface mount (GN) package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
Telecommunications, Infrastructure Power Systems
Distributed Power Architectures
Server Power Supplies
TYPICAL APPLICATIO
V
IN
36V TO 72V
C
IN
R1
12V
OUT
, 240W Converter Efficiency
95
MA
MC
T1
L1
L2
LTC3722
90
EFFICIENCY (%)
V
OUT
12V
MB
1/2
U1
RCS
MD
1/2
U1
U2
T2
ME
C
OUT
85
80
C1
MF
75
0
3722 • TA01A
U1, U2: LTC1693-1 DUAL GATE DRIVER
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
36V
IN
48V
IN
72V
IN
2
4
6
U
U
8 10 12 14 16 18 20
CURRENT (A)
3722 TA01b
372212i
1
LTC3722-1/LTC3722-2
ABSOLUTE
(Note 1)
AXI U RATI GS
V
REF
Output Current ................................ Self Regulated
Outputs (A,B,C,D,E,F) Current ..........................
±100mA
Operating Temperature Range (Note 6)
LTC3722E ........................................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
V
CC
to GND (Low Impedance Source) ......... –0.3 to 10V
(Chip Self Regulates at 10.3V)
UVLO to GND ................................................ –0.3 to V
CC
All Other Pins to GND
(Low Impedance Source) ....................... –0.3 to 5.5V
V
CC
(Current Fed) ................................................. 25mA
PACKAGE/ORDER I FOR ATIO
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
ORDER PART
NUMBER
LTC3722EGN-1
SBUS 10
ADLY 11
UVLO 12
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
2
U
U
W
W W
U
W
TOP VIEW
SYNC
RAMP
CS
COMP
DPRG
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
ORDER PART
NUMBER
LTC3722EGN-2
SBUS 10
ADLY 11
UVLO 12
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
372212i
LTC3722-1/LTC3722-2
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9.5V, C
T
= 270pF, R
DPRG
= 60.4k, R
SPRG
= 100k, T
A
= t
MIN
to t
MAX
,
unless otherwise noted.
SYMBOL
Input Supply
V
CCUV
V
CCHY
I
CCST
I
CCRN
V
SHUNT
R
SHUNT
SUVLO
SHYST
Delay Blocks
DTHR
DHYS
DTMO
DFXT
DFTM
Phase Modulator
I
RMP
I
SLP
DC
MAX
DC
MIN
Oscillator
OSCI
OSCT
OSCV
OSYT
OSYW
OSYR
Initial Accuracy
Total Variation
C
T
Ramp Amplitude
SYNC Threshold
Minimum SYNC Pulse Width
SYNC Frequency Range
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
q
ELECTRICAL CHARACTERISTICS
PARAMETER
V
CC
Under Voltage Lockout
V
CC
UVLO Hysteresis
Start-Up Current
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
Ramp Discharge Current
Slope Compensation Current
Maximum Phase Shift
Minimum Phase Shift
CONDITIONS
Measured on V
CC
Measured on V
CC
V
CC
= V
UVLO
– 0.3V
No Load on Outputs
Current into V
CC
= 10mA
Current into V
CC
= 10mA to 17mA
Measured on UVLO Pin, 7mA into V
CC
Current Flows Out of UVLO Pin, 7mA into V
CC
SBUS = 1.5V
SBUS = 2.25V
SBUS = 1.5V, ADLY/PDLY = 1.7V
R
DPRG
= 60.4K
Measured on SBUS
ADLY,PDLY = 1V, SBUS = V
REF
RAMP = 1V, COMP = 0V, C
T
= 4V,
LTC3722-1 Only
Measured on CS, C
T
= 1V
C
T
= 2.25V
COMP = 4.5V
COMP = 0V
q
q
q
q
q
MIN
TYP
10.25
MAX
10.5
230
8
10.8
3.5
5.2
11.5
1.6
2.4
UNITS
V
V
µA
mA
V
Ω
V
µA
V
V
mA
ns
V
ns
mA
µA
µA
%
3.8
4.2
145
5
10.3
1.1
4.8
8.5
1.4
2.1
5.0
10
1.5
2.25
1.3
100
4
70
50
30
68
95
98.5
0
0.5
275
285
2.2
%
kHz
kHz
V
V
ns
kHz
225
215
250
250
2.2
1.9
100
1000
372212i
3
LTC3722-1/LTC3722-2
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9.5V, T
A
= t
MIN
to t
MAX
, unless otherwise noted.
SYMBOL
Error Amplifier
V
FB
FBI
A
VOL
IIB
V
OH
V
OL
I
SOURCE
I
SINK
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
CLSD
CLDEL
SSI
SSR
FLT
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
Shutdown Current Limit Threshold
Current Limit Delay to Output
Soft-Start Current
Soft-Start Reset Threshold
Fault Reset 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
C
OUT(x)
= 50pF
R
SPRG
= 100k
Measured on CS
Measured on CS
100mV Overdrive on CS (Notes 3, 7)
SS = 2.5V
Measured on SS
Measured on SS
7
0.7
4.5
240
0.55
7.9
8.4
0.6
22
12
5
5
180
270
0.65
80
12
0.4
3.9
17
0.1
3.5
300
0.73
1
30
20
15
15
V
V
Ω
Ω
ns
ns
ns
mV
V
ns
µA
V
V
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
q
ELECTRICAL CHARACTERISTICS
PARAMETER
FB Input Voltage
FB Input Range
Open-Loop Gain
Input Bias Current
Output High
Output Low
Output Source Current
Output Sink Current
CONDITIONS
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
MIN
1.172
–0.3
70
4.7
400
2
4.925
TYP
1.204
90
5
4.92
0.18
800
5
5.00
2
0.9
MAX
1.236
2.5
20
0.4
UNITS
V
V
dB
nA
V
V
µA
mA
5.075
15
10
5.100
45
V
mV
mV
V
mA
4.900
18
5.000
30
Current Limit and Shutdown
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Sync amplitude = 5V
P-P
, pulse width = 50ns. Verify output (A-F)
frequency = 1/2 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 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 temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 7:
Guaranteed by design, not tested in production.
372212i
4
LTC3722-1/LTC3722-2
TYPICAL PERFOR A CE CHARACTERISTICS
Start-Up I
CC
vs V
CC
200
T
A
= 25°C
10.50
T
A
= 25°C
150
100
10.00
FREQUENCY (kHz)
I
CC
(µA)
V
CC
(V)
50
0
0
2
4
V
CC
(V)
6
Leading Edge Blanking Time
vs R
LEB
350
300
5.00
250
BLANK TIME (ns)
T
A
= 25°C
150
100
V
REF
(V)
200
50
0
0 10 20 30 40 50 60
R
LEB
(kΩ)
70 80 90 100
3722 • G04
V
REF
vs Temperature
5.01
100
80
60
40
20
0
–180
–270
–360
GAIN (dB)
5.00
V
REF
(V)
4.99
PHASE (DEG)
4.98
4.97
– 60 – 40 – 20 0
20 40 60
TEMPERATURE (°C)
U W
8
3722 • G01
V
CC
vs I
SHUNT
260
Oscillator Frequency vs
Temperature
C
T
= 270pF
250
10.25
240
9.75
230
10
9.50
0
10
30
20
I
SHUNT
(mA)
40
50
3722 • G02
220
– 60 – 40 – 20 0
20 40 60
TEMPERATURE (°C)
80
100
3722 • G03
V
REF
vs I
REF
5.05
T
J
= 25°C
T
J
= 85°C
4.95
4.90
T
J
= –40°C
4.85
4.80
0
5
10
15 20
25
I
REF
(mA)
30
35
40
3722
• G05
Error Amplifier Gain/Phase
T
A
= 25°C
80
100
10
100
1k
10k
100k
FREQUENCY (Hz)
1M
10M
3722 • G06
3722 • G07
372212i
5
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