POWER LOSS (W)
LTC7820
Fixed Ratio High Power
Inductorless (Charge Pump)
DC/DC Controller
FEATURES DESCRIPTION
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Low Profile, High Power Density, Capable of 500W+ The LTC 7820 is a fixed ratio high voltage high power
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switched capacitor/charge pump controller. The device
Soft Switching: 99% Peak Efficiency and Low EMI
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includes four N-channel MOSFET gate drivers to drive
V Max for Voltage Divider (2:1): 72V
IN
n external power MOSFETs in voltage divider, doubler or
V Max for Voltage Doubler (1:2)/Inverter (1:1): 36V
IN
n inverter configurations. The device achieves a 2:1 step-
Wide Bias V Range: 6V to 72V
CC
down ratio from an input voltage as high as 72V, a 1:2
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Soft Startup into Steady State Operation
step-up ratio from an input voltage as high as 36V, or a
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6.5V to 40V EXTV Input for Improved Efficiency
CC
1:1 inverting ratio from an input voltage up to 36V. Each
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Input Current Sensing and Overcurrent Protection
power MOSFET is switched with 50% duty cycle at a
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Wide Operating Frequency Range: 100kHz to 1MHz
constant pre-programmed switching frequency. System
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Output Short-Circuit/OV/UV Protections with
efficiency can be optimized to over 99%. The LTC7820
Programmable Timer and Retry
provides a small and cost effective solution for high
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Thermally Enhanced 28-Pin 4mm 5mm QFN Package
power, non-isolated intermediate bus applications with
fault protection.
APPLICATIONS
The LTC7820 switching frequency can be linearly
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Bus Converters
programmed from 100kHz to 1MHz. The device is available
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High Power Distributed Power Systems
in a thermally enhanced 28-lead QFN package with some
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Communications Systems no-connect pins for high voltage compatible pin spacing.
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Industrial Applications
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 9484799.
TYPICAL APPLICATION
Very High Efficiency 5A Voltage Divider
Efficiency and Power Loss
10
V vs Load Current
IN
48V/24V
R
SENSE
0.1F 100 2.0
V V 0.005
HIGH_SENSE CC
V = 48V
IN
100
EFFICIENCY
G1
V = 24V
OUT
I
SENSE
0.1F
1.6
99
0.1F
BOOST1
+
I
SENSE
LTC7820
98 1.2
SW1
TIMER
10F
G2
f = 100kHz
s
1F
0.1F 6
97 0.8
RUN BOOST2
V
OUT
V = 24V
IN
24V/12V
12V EXTV V = 12V
CC
OUT
V 10 5A*
LOW
INTV
CC 10F
96 0.4
V
LOW_SENSE
G3 0.1F
10k
1F
POWER LOSS
UV
95 0
10k
BOOST3
0 1 2 3 4 5
HYS_PRGM
LOAD CURRENT (A)
10k
SW3
7820 TA01b
* LOAD CURRENT APPLIED
PGOOD
AFTER STARTUP
G4
FREQ
INTV INTV
CC CC
10k 40k
4.7F
GND
FAULT
7820 TA01a
7820fc
1
For more information www.linear.com/LTC7820
EFFICIENCY (%)LTC7820
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Notes 1, 3)
TOP VIEW
V , V ....................................... 0.3V to 80V
CC HIGH_SENSE
BOOST1 ..................................................... 0.3V to 86V
BOOST2, BOOST3 .......................................0.3V to 51V
28 27 26 25 24 23
SW1 .............................................................. 5V to 80V
V 1 22 BOOST2
HIGH_SENSE
SW3 .............................................................. 5V to 45V NC 2 21 G2
HYS_PRGM
3 20 V
V , V ..................................... 0.3V to 45V LOW
LOW LOW_SENSE
+
TIMER 4 19 V
29 LOW_SENSE
I , I .......................................... 0.3V to 80V
SENSE SENSE
GND
FREQ 5 18 BOOST3
(BOOST1 - SW1), (BOOST2 - V ) ............ 0.3V to 6V
LOW
RUN 6 17 G3
(BOOST3 - SW3) .......................................... 0.3V to 6V
PGOOD 7 16 SW3
INTV , RUN ................................................ 0.3V to 6V
CC
UV 8 15
G4
EXTV , PGOOD ........................................ 0.3V to 45V
9 10 11 12 13 14
CC
HYS_PRGM, FREQ, TIMER, UV ............0.3V to INTV
CC
FAULT ......................................................... 0.3V to 80V
INTV Peak Current (Note 10) ............................150mA
UFD PACKAGE
CC
28-LEAD (4mm 5mm) PLASTIC QFN
Operating Junction Temperature
T = 125C, = 43C/W , = 3.4C/W
JMAX JA JC(bottom)
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
Range (Notes 2, 11) ............................... 40C to 125C
Storage Temperature Range .................. 65C to 150C