switched capacitor/charge pump controller. The device
includes four N-channel MOSFET gate drivers to drive
external power MOSFETs in voltage divider, doubler or
inverter configurations. The device achieves a 2:1 step-
down ratio from an input voltage as high as 72V, a 1:2
step-up ratio from an input voltage as high as 36V, or a
1:1 inverting ratio from an input voltage up to 36V. Each
power MOSFET is switched with 50% duty cycle at a
constant pre-programmed switching frequency. System
efficiency can be optimized to over 99%. The LTC7820
provides a small and cost effective solution for high
power, non-isolated intermediate bus applications with
fault protection.
The LTC7820 switching frequency can be linearly
programmed from 100kHz to 1MHz. The device is available
in a thermally enhanced 28-lead QFN package with some
no-connect pins for high voltage compatible pin spacing.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 9484799.
n
Low Profile, High Power Density, Capable of 500W+
Soft Switching: 99% Peak Efficiency and Low EMI
V
IN
Max for Voltage Divider (2:1): 72V
V
IN
Max for Voltage Doubler (1:2)/Inverter (1:1): 36V
Wide Bias V
CC
Range: 6V to 72V
Soft Startup into Steady State Operation
6.5V to 40V EXTV
CC
Input for Improved Efficiency
Input Current Sensing and Overcurrent Protection
Wide Operating Frequency Range: 100kHz to 1MHz
Output Short-Circuit/OV/UV Protections with
Programmable Timer and Retry
Thermally Enhanced 28-Pin 4mm × 5mm QFN Package
APPLICATIONS
n
n
n
n
Bus Converters
High Power Distributed Power Systems
Communications Systems
Industrial Applications
TYPICAL APPLICATION
Very High Efficiency 5A Voltage Divider
10
0.1µF
100
0.1µF
I
SENSE+
TIMER
0.1µF
RUN
12V
EXTV
CC
LTC7820
V
HIGH_SENSE
I
SENSE–
V
CC
G1
BOOST1
0.1µF
R
SENSE
0.005
V
IN
48V/24V
Efficiency and Power Loss
vs Load Current
100
EFFICIENCY
99
EFFICIENCY (%)
V
IN
= 48V
V
OUT
= 24V
2.0
1.6
POWER LOSS (W)
SW1
G2
BOOST2
V
LOW
10
0.1µF
1µF
10µF
×6
V
OUT
24V/12V
5A*
98
f
s
= 100kHz
97
V
IN
= 24V
V
OUT
= 12V
POWER LOSS
0
1
2
3
LOAD CURRENT (A)
4
5
7820 TA01b
1.2
0.8
INTV
CC
V
LOW_SENSE
10k
G3
UV
HYS_PRGM
PGOOD
FREQ
BOOST3
SW3
G4
INTV
CC
GND
INTV
CC
4.7µF
FAULT
1µF
10µF
96
0.4
10k
10k
95
* LOAD CURRENT APPLIED
AFTER STARTUP
0
10k
40k
7820 TA01a
7820fc
For more information
www.linear.com/LTC7820
1
LTC7820
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 3)
PIN CONFIGURATION
TOP VIEW
BOOST1
22 BOOST2
21 G2
29
GND
20 V
LOW
19 V
LOW_SENSE
18 BOOST3
17 G3
16 SW3
15 G4
9 10 11 12 13 14
FAULT
NC
EXTV
CC
INTV
CC
NC
V
CC
I
SENSE–
I
SENSE+
SW1
NC
G1
V
CC
, V
HIGH_SENSE
....................................... –0.3V to 80V
BOOST1 ..................................................... –0.3V to 86V
BOOST2, BOOST3 .......................................–0.3V to 51V
SW1 .............................................................. –5V to 80V
SW3 .............................................................. –5V to 45V
V
LOW
, V
LOW_SENSE
..................................... –0.3V to 45V
I
SENSE+
, I
SENSE–
.......................................... –0.3V to 80V
(BOOST1 - SW1), (BOOST2 - V
LOW
) ............ –0.3V to 6V
(BOOST3 - SW3) .......................................... –0.3V to 6V
INTV
CC
, RUN ................................................ –0.3V to 6V
EXTV
CC
, PGOOD ........................................ –0.3V to 45V
HYS_PRGM, FREQ, TIMER, UV ............ –0.3V to INTV
CC
FAULT
......................................................... –0.3V to 80V
INTV
CC
Peak Current (Note 10) ............................150mA
Operating Junction Temperature
Range (Notes 2, 11) ............................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
28 27 26 25 24 23
V
HIGH_SENSE
1
NC 2
HYS_PRGM 3
TIMER 4
FREQ 5
RUN 6
PGOOD 7
UV 8
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W ,
θ
JC(bottom)
= 3.4°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC7820EUFD#PBF
LTC7820IUFD#PBF
TAPE AND REEL
LTC7820EUFD#TRPBF
LTC7820IUFD#TRPBF
http://www.linear.com/product/LTC7820#orderinfo
PART MARKING*
7820
7820
PACKAGE DESCRIPTION
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
7820fc
2
For more information
www.linear.com/LTC7820
LTC7820
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= 12V, V
RUN
= 5V, unless otherwise specified.
SYMBOL
V
CC
V
VHIGH_SENSE
V
VLOW_SENSE
V
VLOW
I
Q
V
UVLO
PARAMETER
IC Bias Voltage Range
V
HIGH_SENSE
Voltage Range
V
LOW_SENSE
Voltage Range
V
LOW
Voltage Range
Input DC Supply Current
Shutdown
Normal Operation
Undervoltage Lockout Threshold
(Note 5)
V
RUN
= 0V
V
RUN
= 5V, No Switching
V
INTVCC
Falling
V
INTVCC
Rising
I
SENSE+
= I
SENSE–
= 24V
Pre-Balance Phase, V
HIGH_SENSE
= 24V,
I
SENSE+
= I
SENSE–
= 24V, V
VLOW
= 12V,
V
VLOW_SENSE
= 11V
I
ISENSE–
V
ISENSE
Gate Drivers
R
G2,4
R
G1,3
G1/G2 t
D
G3/G4 t
D
G1/G3 t
D
G2/G4 t
D
RUN Pin
V
RUN
V
RUN,HYS
INTV
CC
Regulator
V
INTVCC_VCC
V
INTVCC_EXT
INTV
CC
Voltage No Load
INTV
CC
Load Regulation
INTV
CC
Voltage No Load with EXTV
CC
INTV
CC
Load Regulation with EXTV
CC
EXTV
CC
Switchover Voltage
EXTV
CC
HYSTERESIS
V
HIGH_SENSE
and V
LOW_SENSE
R
VHIGH_SENSE
I
VLOW_SENSE
V
HIGH_SENSE
to GND Resistance
V
LOW_SENSE
Pin Current
V
CC
= 51V, V
LOW_SENSE
= 45V
1
±1
±10
MΩ
µA
6V < V
CC
< 72V, V
EXTVCC
= 0V
I
CC
= 0 to 60mA, V
EXTVCC
= 0V
12V < V
EXTVCC
< 45V (Note 7)
I
CC
= 0 to 50mA, V
EXTVCC
= 12V
V
EXTVCC
Ramping Positive (Note 9)
6.35
5.4
5.4
5.6
0.8
5.6
0.5
6.5
400
5.9
±2
5.9
±2
6.65
V
%
V
%
V
mV
Run Pin On Threshold
Run Pin On Hysteresis
V
RUN
Rising
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
6
TYP
MAX
72
72
36
36
UNITS
V
V
V
V
µA
mA
V
V
Input/Output Voltage
(Note 6)
0
0
0
60
1.5
4.85
5.05
220
93
350
Overcurrent Protection
I
ISENSE+
I
SENSE+
Pin Current
µA
mA
I
SENSE–
Pin Current
Current Limit Threshold (V
ISNESE+
– V
ISENSE–
)
Pull-Up On-Resistance
Pull-Down On-Resistance
Pull-Up On-Resistance
Pull-Down On-Resistance
G1 Off to G2 On Delay Time
G2 Off to G1 On Delay Time
G3 Off to G4 On Delay Time
G4 Off to G3 On Delay Time
G1 On to G3 On Delay Time
G3 Off to G1 Off Delay Time
G2 On to G4 On Delay Time
G4 Off to G2 Off Delay Time
(Note 4)
(Note 4)
(Note 4)
(Note 4)
l
l
–5
45
1
50
2.5
1.5
2.4
1.1
50
50
60
60
5
10
5
10
5
55
µA
mV
Ω
Ω
Ω
Ω
ns
ns
ns
ns
ns
ns
ns
ns
1.1
1.22
80
1.35
V
mV
7820fc
For more information
www.linear.com/LTC7820
3
LTC7820
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= 12V, V
RUN
= 5V, unless otherwise specified.
SYMBOL
V
LOW
I
SOURCEVLOW
I
SINKVLOW
Oscillator
f
s
f
NOM
I
FREQ
R
FAULT
I
FAULT_LEAK
I
HYS_PRGM
Oscillator Frequency Range
Nominal Frequency
FREQ Setting Current
FAULT
Pull-Down Resistance
FAULT
Leakage Current
HYS_PRGM Setting Current
V
FREQ
= 1.02V
V
FREQ
= 1.02V (Note 3)
V
FAULT
= 0.5V
V
FAULT
= 80V
V
HYS_PRGM
= 1V (Note 3)
V
VHIGH_SENSE
= 24V, V
HYS_PRGM
= 0V
V
VLOW_SENSE
Ramp Up
V
VLOW_SENSE
Ramp Down
V
VHIGH_SENSE
= 24V, V
HYS_PRGM
= 5V
V
VLOW_SENSE
Ramp Up
V
VLOW_SENSE
Ramp Down
V
VHIGH_SENSE
= 24V, V
HYS_PRGM
= 2.4V
V
VLOW_SENSE
Ramp Up
V
VLOW_SENSE
Ramp Down
UV Comparator and PGOOD
V
UVTH
V
UVHYS
R
PGOOD
I
PGOOD_LEAK
Timer
I
TIMER
Timer Pin Current
V
TIMER
< 0.5V or V
TIMER
> 1.2V (Note 3)
0.5V < V
TIMER
< 1.2V (Note 3)
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 LTC7820 is tested under pulsed load conditions such that T
J
≈ T
A
. The LTC7820E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC7820I is guaranteed
over the –40°C to 125°C operating junction temperature range. Note that
the maximum ambient temperature consistent with these specifications
is determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors. T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
• 43°C/W).
Note 3:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
–3.5
–7
µA
µA
UV Pin Comparator Threshold
Undervoltage Hysteresis
PGOOD Pull-Down Resistance
PGOOD Leakage Current
V
PGOOD
= 0.5V
V
PGOOD
= 45V
UV Pin Voltage Rising
0.985
1.01
120
150
300
±1
1.035
V
mV
Ω
µA
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
PARAMETER
Source Current to V
LOW
Pin from I
SENSE+
Sink Current from V
LOW
Pin to GND
CONDITIONS
I
SENSE+
= V
HIGH_SENSE
= 24V,
V
LOW_SENSE
= 11V, V
LOW
= 12V, Timer = 1V
I
SENSE+
= V
HIGH_SENSE
= 24V,
V
LOW_SENSE
= 13V, V
LOW
= 12V, Timer = 1V
MIN
TYP
93
50
MAX
UNITS
mA
mA
100
500
–9.5
–10
200
–9.3
12.2
11.6
12.7
11.1
14.15
9.5
–10
12.3
11.7
12.8
11.2
14.3
9.65
1000
–10.5
400
±2
–10.7
12.4
11.8
12.9
11.3
14.45
9.8
kHz
kHz
µA
Ω
µA
µA
V
V
V
V
V
V
FAULTB and HYS_PRGM
V
VLOW_SENSE_FAULT
V
LOW_SENSE
Voltage Trigger Fault
Note 4:
Delay times are measured using 50% levels with SW3 = V
LOW
=
6V, SW1 = 12V.
Note 5:
The maximum output operating voltage for divider applications is
36V, the maximum input operating voltage for doubler applications is 36V.
Note 6:
The maximum input operating voltage for divider applications is
72V, the maximum output operating voltage for doubler applications is 72V.
Note 7:
When V
CC
> 15V, EXTV
CC
lower than V
CC
is recommended to
improve efficiency and reduce IC Temperature.
Note 8:
All the voltage is referred to the GND pin unless otherwise
specified.
Note 9:
EXTV
CC
is enabled only if V
CC
is higher than 7V.
Note 10:
Guaranteed by design.
Note 11:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum junction temperature
may impair device reliability or permanently damage the device.
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