LT8309

LT8309 (Rev. B)

Document overview

• Manufacturer or author: Analog Devices, Inc.
• PDF pages: 14

Technical content

Rev. BFor more information www.analog.comDocument Feedback TYPICAL APPLICATION FEATURES DESCRIPTION Secondary-Side Synchronous Rectifier Driver The LT®8309 is a secondary-side synchronous rectifier driver that replaces the output rectifier diode in a flyback topology. By replacing the diode with a N-channel MOSFET, applications are no longer restricted by the heat constraints of the output diode. The IC replicates the behavior of a diode by sensing the drain-to-source voltage to determine when the current becomes negative. The LT8309's low minimum on- and off-times help improve noise immunity. The fast propagation delay of 26ns allows applications to operate in discontinuous conduction mode (DCM) and critical conduction mode (CrCM). The gate driver features a 0.8Ω pull-down device for fast turn-offs. The 40V V CC rating allows the part to be driven from the output volt - age or the rectified drain voltage of the MOSFET. A low quiescent current of 400µA maximizes efficiency at low output currents. 40W, 5V Isolated Telecom Supply Efficiency vs Load Current

APPLICATIONS

n Works with DCM and BCM/CrCM Conduction Mode Flyback Topologies n VCC: 4.5V to 40V n Supports Up to 150V MOSFETs n 26 ns Turn-Off Propagation Delay n Accurate Minimum On and Off Timers for Reliable Operation n Adjustable and Accurate T rip Point: +5mV to –30mV n 1Ω Gate Driver Pull-Down n SOT -23 5-Lead Package n High Output Current Flybacks n High Efficiency Flybacks All registered trademarks and trademarks are the property of their respective owners. INTVCC VCC VOUT+ 5V , 8A VOUT– 6.2V VIN 36V TO 72V GATE

8309 TA01a

6.04k 147k LT8309 0.1µF 30.9k 12.1k 15nF GATE SENSE RREF INTVCCVC SS TC EN/UVLO RFB GND L T3748 5.33:1 10/uni03A9 2.2k 4.7µF 4.7µF 400µF412k 15.4k 12m/uni03A9 10µF 1µF VIN LOAD CURRENT (A) EFFICIENCY (%) 1 2 3 4 6 5 7 100

8309 TA01b

VIN = 48V WITH PDS760 DIODE VIN = 48V WITH L T8309

Rev. B For more information www.analog.com PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS IN DRAIN Maximum Junction Temperature Operating Temperature Range (Note 2) Storage Temperature Range (Note 1) GATE 1 GND 2 TOP VIEW S5 PACKAGE 5-LEAD PLASTIC TSOT-23 INTVCC 3

5 DRAIN

4 VCC

θJA = 215°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT8309ES5#TRMPBF LT8309ES5#TRPBF L TGFZ 5-Lead Plastic TSOT-23 –40°C to 125°C LT8309IS5#TRMPBF LT8309IS5#TRPBF L TGFZ 5-Lead Plastic TSOT-23 –40°C to 125°C LT8309HS5#TRMPBF LT8309HS5#TRPBF L TGFZ 5-Lead Plastic TSOT-23 –40°C to 150°C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.

Rev. BFor more information www.analog.com

ELECTRICAL CHARACTERISTICS

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: The LT8309E is guaranteed to meet performance specifications from 0°C to 125°C operating junction temperature. Specifications over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT8309I is guaranteed over the full –40°C to 125°C operating junction PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage Range l 4.5 40 V VCC Quiescent Current Not Switching, INTVCC = 8V 300 345 µA Comparator Turn-On Threshold RS = 0Ω l –73 –57 –45 mV Turn-Off Threshold RS = 0Ω l 21 25 mV mV Drain Voltage Latch Reset RS = 0Ω 1.21 V Minimum Off-Time 75 95 115 ns Minimum On-Time 310 360 410 ns Drain Current Out of Pin l 9.5 10 10.5 µA INTVCC Linear Regulator INTVCC Quiescent Current Not Switching, INTVCC = 8V 115 138 µA INTVCC Voltage Range 4.5 10 V INTVCC Regulation Voltage l 6.8 7 7.2 V INTVCC UVLO 4.03 V Dropout (VCC to INTVCC) IINTVCC = –10mA, VIN = 7V 1 1.3 1.6 V Current Limit l 30 42 55 mA Gate Driver Turn-On Propagation Delay (tD(ON)) RS = 0Ω, –100mVOD, VDS to VGATE 31 40 ns Turn-Off Propagation Delay (tD(OFF)) RS = 0Ω, –100mVOD, VDS to VGATE 26 36 ns tr GATE Driver Output Rise Time CL = 3300pF 21 ns tf GATE Driver Output Fall Time CL = 3300pF 11 ns Pull-Up Resistance 2.7 Ω Pull-Down Resistance 0.8 Ω The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. temperature range. The LT8309H is guaranteed over the full –40°C to 150°C operating junction temperature range. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125°C. Note 3: The LT8309 includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 150°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability.

Rev. B For more information www.analog.com TEMPERATURE (°C) –50 VCC IQ CURRENT (µA) 150 250 –25 0 25 50 100 75 125 100 200 350 450 300 400 150

8309 G01

TEMPERATURE (°C) –50 INTVCC IQ CURRENT (µA) –25 0 25 50 100 75 125 150

8309 G02

INTVCC VOLTAGE (V) V CC VOL TAGE (V) 0 10 20 30 40

8309 G04

TEMPERATURE (°C) –50 3.0 THRESHOLD VOLTAGE (V)3.5 4.5 –25 0 25 50 100 75 125 5.0 4.0 150

8309 G05

INTVCC CURRENT (mA) INTVCC REGULATOR DROPOUT (V) 1.5 10 20 30 2.5 1.0 0.5 2.0

8309 G06

VCC = 7V TEMP = –50°C TEMP = 25°C TEMP = 100°C TEMP = 150°C TEMPERATURE (°C) –50 INTVCC DROPOUT (V) 1.0 –25 0 25 50 100 75 125 2.0 0.5 1.5 150

8309 G07

VCC = 7V ILOAD = 0mA ILOAD = 5mA ILOAD = 10mA ILOAD = 20mA TEMPERATURE (°C) –50 INTVCC CURRENT LIMIT (mA) –25 0 25 50 100 75 125 150

8309 G08

TYPICAL PERFORMANCE CHARACTERISTICS INTVCC Voltage vs VCC Voltage INTVCC Undervoltage Lockout vs Temperature INTVCC Regulator Dropout vs INTVCC Current INTVCC Dropout vs Temperature INTVCC Current Limit vs Temperature Minimum On-Time and Off-Time vs Temperature IVCC vs Temperature IINTVCC vs Temperature INTVCC vs Temperature TEMPERATURE (°C) –100 –50 TIME (ns) 0 50 100 150 200

8309 G09

TEMPERATURE (°C) –50 6.0 INTVCC VOLTAGE (V) 6.4 6.8 7.2 –25 0 25 50 100 75 125 8.0 7.8 6.2 6.6 7.0 7.4 7.6 150

8309 G03

Rev. BFor more information www.analog.com TEMPERATURE (°C) –50 DRAIN PIN CURRENT (µA) –25 0 25 50 100 75 125 150

8309 G10

TEMPERATURE (°C) –50 TURN-ON THRESHOLD (mV) –25 0 25 50 100 75 125 150

8309 G11

–80 –70 –60 –50 –40 –75 –65 –55 –45 TEMPERATURE (°C) –50 TURN-OFF THRESHOLD (mV) –25 0 25 50 100 75 125 150

8309 G12

TEMPERATURE (°C) –50 1.00 THRESHOLD VOLTAGE (V)1.10 1.20 1.30 –25 0 25 50 100 75 125 1.40 1.05 1.15 1.25 1.35 150

8309 G13

TYPICAL PERFORMANCE CHARACTERISTICS Latch Reset Threshold vs Temperature GATE Rise and Fall Time vs Charge GATE Current vs Charge DRAIN Pin Current vs Temperature Comparator Turn-On Threshold vs Temperature Comparator Turn-Off Threshold vs Temperature TIME (ns) 150 200 100 FALL TIME RISE TIME CHARGE (nC) 0 60 12030 90 150

8309 G14

TIME (ns) 1.0 2.0 3.0 4.0 0.5 1.5 2.5 3.5 CHARGE (nC)

8309 G15

Rev. B For more information www.analog.com BLOCK DIAGRAM PIN FUNCTIONS GATE (Pin 1): N-Channel MOSFET Gate Driver Output. Switches between INTVCC and GND. Driven to GND during undervoltage lockout of INTVCC. GND (Pin 2): Ground. INTVCC (Pin 3): Regulated Supply for Internal Loads, and GATE Driver. Supplied from VCC and regulates to 7V (typical). INTVCC must be bypassed with a 4.7µF capacitor placed close to the pin. VCC (Pin 4): Input Voltage. This pin supplies current to the internal start-up circuitry and to the INTVCC LDO. This pin must be locally bypassed with a capacitor. DRAIN ( Pin 5): Current Sense Pin. This pin senses the voltage across the drain-to-source of the external N-channel MOSFET . A series resistor is needed to set the offset voltage and needs to be at least 800Ω. The offset is equal to: 20mV • 1− R 2000 ⎝⎜ ⎞ VBIAS 8309 BD INTVCC INTVCC VBIAS VCC GATE GND DRAIN 1.25V 10µA10µA LOGIC

8309 F01

fast comparator and a powerful gate driver. set the trip point to –10mV, a 3000Ω resistor is needed. eliminate the chance that ringing triggers the comparator. before the comparator is re-enabled. Figure 1. Drain and Gate Waveforms

8309 F02

to prevent switching until the INTVCC voltage is above 4V. needed to provide the current needed for the gate driver. down and may cause thermal issues with the MOSFET. voltage to keep the drain-to-source current from reversing. to eliminate the cross-conduction. Figure 2. Short-Circuit Application Circuit

Rev. B For more information www.analog.com TYPICAL APPLICATIONS 60W, 12V Output, Isolated Telecom Supply INTVCC VCC VOUT+ 12V , 5A VOUT– 13V CENTRAL SEMI: CMZ5928B VIN 36V TO 72V GATE

8309 TA02

6.04k 158k LT8309 0.1µF 57.6k 47nF 9m/uni03A9 470pF GATE SENSE RREF INTVCCVC SS TC EN/UVLO RFB GND L T3748 2.67:1 PULSE: PA1736NL 10/uni03A9 2.37k 4.7µF INFINEON: BSC320N20NS3 INFINEON: BSC047N08NS3 4.7µF 300µF412k 15.4k 10µF 1µF VIN

Rev. BFor more information www.analog.com 40W, 5V Isolated Telecom Supply TYPICAL APPLICATIONS INTVCC VCC VOUT+ 5V , 8A VOUT– 6.2V CENTRAL SEMI: CMZ5920B VIN 36V TO 72V GATE

8309 TA03

6.04k 147k LT8309 0.1µF 30.9k 12.1k 15nF 12m/uni03A9 GATE SENSE RREF INTVCCVC SS TC EN/UVLO RFB GND L T3748 5.33:1 PULSE: PA1735NL 10/uni03A9 2.15k 4.7µF INFINEON: BSC320N20NS3 INFINEON: BSC028N06LS 4.7µF 400µF412k 15.4k 10µF 1µF VIN

Rev. B For more information www.analog.com PACKAGE DESCRIPTION 1.50 – 1.75 (NOTE 4)2.80 BSC 0.30 – 0.45 TYP

5 PLCS (NOTE 3)

DATUM ‘A’ 0.09 – 0.20 (NOTE 3) S5 TSOT-23 0302 REV B PIN ONE

2.90 BSC

(NOTE 4)

0.95 BSC

1.90 BSC

0.80 – 0.90

1.00 MAX

0.01 – 0.100.20 BSC 0.30 – 0.50 REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193

3.85 MAX

0.62 MAX 0.95 REF RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 1.4 MIN2.62 REF

1.22 REF

(Reference LTC DWG # 05-08-1635 Rev B)

Rev. BFor more information www.analog.com 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

REVISION HISTORY

REV DATE DESCRIPTION PAGE NUMBER A 11/14 Added H-Grade Version 2, 3 B 08/20 Updated Comparator Turn-On Threshold Min and INTV CC Quiescent Current in EC table Updated Order Info table

Rev. B For more information www.analog.com  ANALOG DEVICES, INC. 2020 www.analog.com RELATED PARTS TYPICAL APPLICATION PART NUMBER DESCRIPTION COMMENTS LT3748 100V Isolated Flyback Controller 5V ≤ VIN ≤ 100V, No-Opto Flyback, MSOP-16 Package LT3798 Offline Isolated No-Opto-Coupler Flyback Controller with Active PFC VIN and VOUT Limited Only by External Components, MSOP-16 Package LT3799/LT3799-1 Offline Isolated Flyback LED Controller with Active PFC V IN and VOUT Limited Only by External Components, MSOP-16 Package LT3957A/LT3958 40V/80V Flyback/Boost/Inverting/SEPIC Converter Monolithic with Integrated 5A/3.3A Switch LT3573/LT3574/ LT3575 40V Isolated Flyback Converters Monolithic No-Opto Flybacks with Integrated 1.25A/0.65A/2.5A Switch LT3757A/LT3759/ LT3758 40V/100V Boost, Flyback, SEPIC and Inverting Controllers Universal Controllers with Small Package and Powerful Gate Drive LT8302 Micropower No-Opto Isolated Flyback Converter 2.8V ≤ V IN ≤ 42V, with Integrated 3.6A, 65V DMOS Power Switch, 106µA Quiescent Current, SO-8 Package 33W, 3.3V Isolated Telecom Supply INTVCC VCC VOUT+ 3.3V , 10A VOUT– 3.9V CENTRAL SEMI: CMZ5915B VIN 36V TO 72V GATE

8309 TA04

6.04k 150k LT8309 0.1µF 19.1k 2.5k 22nF 15m/uni03A9 GATE SENSE RREF INTVCCVC SS TC EN/UVLO RFB GND L T3748 8:1.4 PULSE: PA1477NL 20/uni03A9 4.7µF INFINEON: BSC320N20NS3 INFINEON: BSC016N04LS 4.7µF 1000µF412k 15.4k 10µF 1µF VIN 40/uni03A9