LTC1922-1
Synchronous Phase
Modulated Full-Bridge Controller
FEATURES
DESCRIPTIO
TM
n
Adaptive DirectSense Zero Voltage Switching The LTC 1922-1 phase shift PWM controller provides all
n
Integrated Synchronous Rectification Control for of the control and protection functions necessary to imple-
Highest Efficiency ment a high performance, zero voltage switched, phase
n
Output Power Levels from 50W to Kilowatts shift, full-bridge power converter with synchronous recti-
n
Very Low Start-Up and Quiescent Currents fication. The part is ideal for developing isolated, low
n
Compatible with Voltage Mode and Current Mode voltage, high current outputs from a high voltage input
Topologies source. The LTC1922-1 combines the benefits of the full-
n
Programmable Slope Compensation bridge topology with fixed frequency, zero voltage switch-
n
Undervoltage Lockout Circuitry with 4.2V Hysteresis ing operation (ZVS). Adaptive ZVS circuity controls the
and Integrated 10.3V Shunt Regulator turn-on signals for each MOSFET independent of internal
n
Fixed Frequency Operation to 1MHz and external component tolerances for optimal perfor-
n
50mA Outputs for Bridge Drive and Secondary Side mance.
Synchronous Rectifiers
The LTC1922-1 also provides secondary side synchro-
n
Soft-Start, Cycle-by-Cycle Current Limiting and
nous rectifier control. The device uses peak current mode
Hiccup Mode Short-Circuit Protection
control with programmable slope comp and leading edge
n
5V, 15mA Low Dropout Regulator
blanking.
n
20-Pin PDIP and SSOP Packages
The LTC1922-1 features extremely low operating and
U
APPLICATIO S
start-up currents to simplify off-line start-up and bias
circuitry. The LTC1922-1 also includes a full range of
n
Telecommunications, Infrastructure Power Systems
protection features and is available in 20-pin through hole
n
Distributed Power Architectures
(N) and surface mount (G) packages.
n
Server Power Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
n
DirectSense is a trademark of Linear Technology Corporation.
High Density Power Modules
TYPICAL APPLICATIO
V
IN
48V
BIAS
Efficiency
SUPPLY
100
V
OUT
3.3V
90
V = 48V
IN
V = 36V
IN
80
LTC1922-1 70
ISOLATED
60
FEEDBACK
0 10 20 30 40
LOAD CURRENT (A)
1922 TA01b
1922 TA01a
1
EFFICIENCY (%)
U
ULTC1922-1
UUW
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
ORDER PART
V to GND
CC
SYNC 1 20 C
T NUMBER
Low Impedance Source ......................... 0.3V to 10V
RAMP 2 19 GND
(Chip Self Regulates at 10.3V)
CS 3 18 OUTA
LTC1922EG-1
All Other Pins to GND
COMP 4 17 OUTB
LTC1922IG-1
(Low Impedance Source) ..................... 0.3V to 5.5V
R 5 16 OUTC
LEB
LTC1922EN-1
V (Current Fed).................................................. 25mA
FB 6 15 V
CC
CC
LTC1922IN-1
V Output Current ................................ Self Regulated SS 7 14 OUTD
REF
8 13 OUTE
Outputs (A, B, C, D, E, F) Current ..................... 100mA PDLY
9 12 OUTF
SBUS
Operating Temperature Range (Note 5)
10 11 V
ADLY REF
LTC1922E ........................................... 40 C to 85 C
LTC1922I............................................ 40 C to 85 C
G PACKAGE N PACKAGE
20-LEAD PLASTIC SSOP 20-LEAD PDIP
Storage Temperature Range ................. 65 C to 125 C
T = 125 C, q = 110 C/W (G)
JMAX JA
Lead Temperature (Soldering, 10 sec).................. 300 C T = 125 C,q = 62 C/W (N)
JMAX JA
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at V = 9.5V, C = 180pF, T = T to T unless other wise noted.
CC T A MIN MAX
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Supply
UVLO Undervoltage Lockout Measured on V 10.25 10.7 V
CC
UVHY UVLO Hysteresis Measured on V 3.8 4.2 V
CC
I Start-Up Current V = V 0.3V l 145 250 m A
CCST CC UVLO
I Operating Current 47 mA
CCRN
V Shunt Regulator Voltage Current Into V = 10mA 10.2 10.8 V
SHUNT CC
R Shunt Resistance Current Into V = 7mA to 17mA 1.5 2 W
SHUNT CC
Delay Blocks
DTHR Delay Pin Threshold SBUS = 1.5V 1.38 1.50 1.62 V
ADLY and PDLY SBUS = 2.25V 2.08 2.25 2.42 V
DHYS Delay Hysteresis Current SBUS = 1.5V, ADLY/PDLY = 1.6V 1.1 1.3 1.45 mA
ADLY and PDLY
DTMO Delay Time-Out SBUS = 1.5V 600 ns
SBUS = 2.25V 900 ns
DZRT Zero Delay Threshold Measured on SBUS 3 4.15 5 V
Phase Modulator
ROS RAMP Offset Voltage Measured on COMP, RAMP = 0V 0.4 V
I RAMP Discharge Current RAMP = 1V, COMP = 0V 30 50 mA
RMP
I Slope Compensation Current Measured on CS, C = 1.5V 35 55 75 m A
SLP T
C = 3V 70 110 150 m A
T
DCMX Maximum Phase Shift COMP = 4V l 95 99.5 %
DCMN Minimum Phase Shift COMP = 0V l 0.1 0.6 %
2
U WWW