LTC1922EG-1#PBF Linear Technology, LTC1922EG-1#PBF Datasheet

IC CTLR PWM SYNC 20SSOP

LTC1922EG-1#PBF

Manufacturer Part Number
LTC1922EG-1#PBF
Description
IC CTLR PWM SYNC 20SSOP
Manufacturer
Linear Technology
Datasheet

Specifications of LTC1922EG-1#PBF

Pwm Type
Voltage/Current Mode
Number Of Outputs
1
Frequency - Max
1MHz
Duty Cycle
99%
Buck
No
Boost
No
Flyback
No
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
-40°C ~ 85°C
Package / Case
20-SSOP
Frequency-max
1MHz
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Supply
-

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LTC1922EG-1#PBFLTC1922EG-1
Manufacturer:
IBM
Quantity:
942
Company:
Part Number:
LTC1922EG-1#PBFLTC1922EG-1
Manufacturer:
LT
Quantity:
20 000
FEATURES
APPLICATIO S
TYPICAL APPLICATIO
Telecommunications, Infrastructure Power Systems
Distributed Power Architectures
Server Power Supplies
High Density Power Modules
Adaptive DirectSense
Integrated Synchronous Rectification Control for
Highest Efficiency
Output Power Levels from 50W to Kilowatts
Very Low Start-Up and Quiescent Currents
Compatible with Voltage Mode and Current Mode
Topologies
Programmable Slope Compensation
Undervoltage Lockout Circuitry with 4.2V Hysteresis
and Integrated 10.3V Shunt Regulator
Fixed Frequency Operation to 1MHz
50mA Outputs for Bridge Drive and Secondary Side
Synchronous Rectifiers
Soft-Start, Cycle-by-Cycle Current Limiting and
Hiccup Mode Short-Circuit Protection
5V, 15mA Low Dropout Regulator
20-Pin PDIP and SSOP Packages
SUPPLY
BIAS
LTC1922-1
U
TM
Zero Voltage Switching
U
48V
V
IN
Modulated Full-Bridge Controller
FEEDBACK
ISOLATED
DESCRIPTIO
The LTC
of the control and protection functions necessary to imple-
ment a high performance, zero voltage switched, phase
shift, full-bridge power converter with synchronous recti-
fication. The part is ideal for developing isolated, low
voltage, high current outputs from a high voltage input
source. The LTC1922-1 combines the benefits of the full-
bridge topology with fixed frequency, zero voltage switch-
ing operation (ZVS). Adaptive ZVS circuity controls the
turn-on signals for each MOSFET independent of internal
and external component tolerances for optimal perfor-
mance.
The LTC1922-1 also provides secondary side synchro-
nous rectifier control. The device uses peak current mode
control with programmable slope comp and leading edge
blanking.
The LTC1922-1 features extremely low operating and
start-up currents to simplify off-line start-up and bias
circuitry. The LTC1922-1 also includes a full range of
protection features and is available in 20-pin through hole
(N) and surface mount (G) packages.
DirectSense is a trademark of Linear Technology Corporation.
1922 TA01a
, LTC and LT are registered trademarks of Linear Technology Corporation.
®
V
3.3V
1922-1 phase shift PWM controller provides all
OUT
Synchronous Phase
U
100
90
80
70
60
0
V
IN
= 48V
10
LOAD CURRENT (A)
Efficiency
LTC1922-1
20
V
IN
= 36V
30
1922 • TA01b
40
1

Related parts for LTC1922EG-1#PBF

LTC1922EG-1#PBF Summary of contents

Page 1

... The LTC1922-1 features extremely low operating and start-up currents to simplify off-line start-up and bias circuitry. The LTC1922-1 also includes a full range of protection features and is available in 20-pin through hole (N) and surface mount (G) packages. , LTC and LT are registered trademarks of Linear Technology Corporation. DirectSense is a trademark of Linear Technology Corporation 48V ...

Page 2

... SBUS = 2.25V SBUS = 1.5V, ADLY/PDLY = 1.6V SBUS = 1.5V SBUS = 2.25V Measured on SBUS Measured on COMP, RAMP = 0V RAMP = 1V, COMP = 0V Measured COMP = 4V COMP = ORDER PART NUMBER GND LTC1922EG-1 18 OUTA LTC1922IG-1 17 OUTB 16 OUTC LTC1922EN LTC1922IN OUTD 13 OUTE 12 OUTF V 11 REF N PACKAGE 20-LEAD PDIP = 110 C/W ( C/W (N) unless other wise noted ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at V SYMBOL PARAMETER Oscillator OSCT Total Variation OSCV C RAMP Amplitude T OSYT SYNC Threshold OSYW Minimum SYNC Pulse Width OSYWX Maximum SYNC Pulse Width OSOP SYNC Output Pulse Width Error Amplifier ...

Page 4

LTC1922 TYPICAL PERFOR A CE CHARACTERISTICS Start- 200 150 100 (V) CC 1922 • G01 Leading Edge Blanking Time vs ...

Page 5

W U TYPICAL PERFOR A CE CHARACTERISTICS Start- Temperature CC 160 150 140 130 120 110 100 –55 – 125 TEMPERATURE ( C) 1922 • G10 V Shunt Voltage vs Temperature ...

Page 6

LTC1922 PIN FUNCTIONS SYNC (Pin 1): Synchronization Input/Output for the Oscillator. Terminate SYNC with a 5.1k resistor to GND. RAMP (Pin 2): Input to Phase Modulator Comparator. The voltage on RAMP is internally level shifted by 400mV. ...

Page 7

W BLOCK DIAGRA UVLO SHUNT REG 10.25V “ON” 6V “0FF” ERROR AMPLIFIER FB 6 – + 1.2V COMP 4 + – RAMP 2 BLANK V REF – 600mV SHUTDOWN 5 R LEB CURRENT LIMIT ...

Page 8

LTC1922-1 U OPERATIO Phase Shift Full-Bridge PWM Conventional full-bridge switching power supply topolo- gies are often employed for high power, isolated DC/DC and off-line converters. Although they require two addi- tional switching elements, substantially greater power and higher efficiency can ...

Page 9

U OPERATIO Each full cycle of the transformer has two distinct periods in which power is delivered to the output, and two “free- wheeling” periods. The two sides of the external bridge have fundamentally different operating characteristics that become important ...

Page 10

LTC1922-1 U OPERATIO . a nd must be considered when specifying the power trans- former. If ZVS is required over the entire range of loads, a small commutating inductor is added in series with the primary to aid with the ...

Page 11

U OPERATIO Zero Voltage Switching (ZVS) A lossless switching transition requires that the respective full-bridge MOSFETs be switched to the “ON” state at the exact instant their drain to source voltage is zero. Delaying the turn-on results in lower efficiency ...

Page 12

LTC1922-1 U OPERATIO PDLY corresponding to several volts across the MOSFET, the LTC1922-1 can “anticipate” a zero voltage VDS and signal the external driver and switch to turn-on. The amount of anticipation can be tailored for any application by modifying ...

Page 13

U OPERATIO Off-Line Bias Supply Generation If a regulated bias supply is not available to provide V voltage to the LTC1922-1 and supporting circuitry, one must be generated. Since the power requirement is small, approximately 1W, and the regulation is ...

Page 14

LTC1922-1 U OPERATIO 2. The LTC1922-1 can either synchronize other PWMs synchronized to an external frequency source or PWM chip. See Figure 6 for details SLAVE( 1. MASTER LTC1922-1 5.1k ...

Page 15

U OPERATIO PULSE BY PULSE CURRENT LIMIT CS 400mV CURRENT LIMIT R CS 600mV The pulse-by-pulse comparator has a 400mV nominal threshold, which can reduce sense resistor losses by 67% compared to previous solutions. This corresponds ...

Page 16

LTC1922-1 U OPERATIO 2 0.025 S 1 48V 3. 1.4 1.2 1.0 0.8 0.6 0.4 0 OUTPUT CURRENT (A) ...

Page 17

U OPERATIO Phase Modulator The LTC1922-1 phase modulation control circuitry is comprised of the phase modulation comparator and logic, the error amplifier, and the soft-start amplifier (see Figure 11). Together, these elements develop the required phase overlap (duty cycle) required ...

Page 18

LTC1922-1 U OPERATIO Selecting the Power Stage Components Perhaps the most critical part of the overall design of the converter is selecting the power MOSFETs, transformer, inductors and filter capacitors. Tremendous gains in effi- ciency, transient performance and overall operation ...

Page 19

U OPERATIO where MOSFET D-S capacitance OSS l = magnetizing inductance MAG f = switching frequency duty cycle L = leakage inductance L For a 48V to 3.3V/5V, 200W converter, the following values were derived: ...

Page 20

LTC1922-1 U OPERATIO snubber capacitor and/or a very low resistance turn-off driver. If synchronous rectifier MOSFETs are used on the secondary, the same general guidelines apply. Keep in mind, however, that the BV rating needed for these can DSS be ...

Page 21

U OPERATIO slower. A linearized SPICE macromodel of the control loop is very helpful tool to quickly evaluate the frequency response of various compensation networks. Polymer Electrolytic (see Figure 12) 1/(2 C low frequency pole. 1/( sets ...

Page 22

LTC1922-1 U OPERATIO the start of a new power cycle. A noninverting MOSFET driver such as the LTC1693-1 (Figure 14) is used so that a single signal transformer with secondary center tap can be employed to translate the drive signals ...

Page 23

... MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 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. ...

Page 24

... COLL GNDF COMP GNDS RTOP R36 7 8 RMID REF 100k 13.2V IN 1922f LT/TP 0501 2K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2000 +V OUT + C15 R15 2k 0.125W C17 0.22 F 50V – V OUT +V OUT R33 R32 3.01k 10k 1% C26 0.02 F R37 9.3k 1% – ...

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