Document
LTC3813
100V Current Mode Synchronous Step-Up Controller
FEATURES
n High Output Voltages: Up to 100V n Large 1Ω Gate Drivers n No Current Sense Resistor Required n Dual N-Channel MOSFET Synchronous Drive n ±0.5% 0.8V Voltage Reference n Fast Transient Response n Programmable Soft-Start n Generates 10V Driver Supply from Input Supply n Synchronizable to External Clock n Power Good Output Voltage Monitor n Adjustable Off-Time/Frequency: tOFF(MIN) < 100ns n Adjustable Cycle-by-Cycle Current Limit n Programmable Undervoltage Lockout n Output Overvoltage Protection n 28-Pin SSOP Package
APPLICATIONS
n 24V Fan Supplies n 48V Telecom and Base Station Power Supplies n Networking Equipment, Servers n Automotive and Industrial Control Systems
DESCRIPTION
The LTC3813 is a synchronous step-up switching regulator controller that can generate output voltages up to 100V. The LTC3813 uses a constant off-time peak current control architecture with accurate cycle-by-cycle current limit, without requiring a sense resistor.
A precise internal reference provides ±0.5% DC accuracy. A high bandwidth (25MHz) error amplifier provides very fast line and load transient response. Large 1Ω gate drivers allow the LTC3813 to drive multiple MOSFETs for higher current applications. The operating frequency is selected by an external resistor and is compensated for variations in VIN and can also be synchronized to an external clock for switching-noise sensitive applications. A shutdown pin allows the LTC3813 to be turned off, reducing the supply current to 240μA.
PARAMETER
Maximum VOUT MOSFET Gate Drive INTVCC UV+ INTVCC UV –
LTC3813 100V
6.35V to 14V 6.2V 6V
LTC3814-5 60V
4.5V to 14V 4.2V 4V
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6304066, 6476589, 6580258, 6677210, 6774611.
TYPICAL APPLICATION
High Efficiency High Voltage Step-Up Converter
50k
500k VOUT
1000pF
0.01μF 100k
100pF
IOFF
NDRV
PGOOD
BOOST
LTC3813
VRNG
TG
SYNC SS SHDN ITH VFB
SGND
SW EXTVCC DRVCC INTVCC SENSE+
BG SENSE– BGRTN
0.1μF
10μH
VIN
+
10V TO 40V
22μF
M1 Si7850DP
VOUT 50V/5A
D1 MBR1100
M2 Si7850DP 2x
1μF
30.9k
+
270μF 2x
499Ω
3813 TA01
EFFICIENCY (%)
Efficiency vs Load Current
100 VIN = 36V
95
VIN = 24V
VIN = 12V
90
85
80
0
1
2
3
4
5
LOAD (A)
3813 TA01b
3813fb
1
LTC3813
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltages INTVCC, DRVCC....................................... –0.3V to 14V (DRVCC - BGRTN), (BOOST - SW).......... –0.3V to 14V BOOST ................................................. –0.3V to 114V BGRTN........................................................ –5V to 0V EXTVCC .................................................. –0.3V to 15V
(NDRV - INTVCC) Voltage ........................... –0.3V to 10V SW, SENSE+ Voltage ................................... –1V to 100V IOFF Voltage .............................................. –0.3V to 100V SS Voltage ................................................... –0.3V to 5V PGOOD Voltage............................................ –0.3V to 7V VRNG, VOFF, SYNC, SHDN,
UVIN Voltages........................................ –0.3V to 14V PLL/LPF, FB Voltages................................. –0.3V to 2.7V TG, BG, INTVCC, EXTVCC RMS Currents .................50mA Operating Temperature Range (Note 2)
LTC3813E............................................. –40°C to 85°C LTC3813I............................................ –40°C to 125°C Junction Temperature (Notes 3, 7)........................ 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
IOFF 1 NC 2 NC 3 VOFF 4 VRNG 5 PGOOD 6 SYNC 7 ITH 8 VFB 9 PLL/LPF 10 SS 11 SGND 12 SHDN 13 UVIN 14
TOP VIEW
28 BOOST 27 TG 26 SW 25 SENSE+ 24 NC 23 NC 22 NC 21 SENSE– 20 BGRTN 19 BG 18 DRVCC 17 INTVCC 16 EXTVCC 15 NDRV
G PACKAGE 28-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 100°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3813EG#PBF
LTC3813EG#TRPBF
LTC3813EG
28-Lead Plastic SSOP
LTC3813IG#PBF
LTC3813IG#TRPBF
LTC3813IG
28-Lead Plastic SSOP
Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
TEMPERATURE RANGE –40°C to 85°C –40°C to 125°C
ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, INTVCC = DRVCC = VBOOST = VOFF = VRNG = SHDN = UVIN = VEXTVCC = VNDRV = 10V, VSYNC = VSENSE.