LT1680
High Power DC/DC
Step-Up Controller
FEATURES
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DESCRIPTION
The LT
廬
1680 is a high power, current mode switching
power supply controller optimized for boost topologies.
The IC drives N-channel MOSFET switches for DC/DC
converters in applications up to 60V input. A high current
gate drive output handles up to 10,000pF gate capaci-
tance, enabling the construction of high power DC/DC
converters. Current sense common mode range up to 60V
allows current sensing to be referenced to the input
supply, eliminating the need for sense blanking circuits.
The LT1680 incorporates programmable average current
limiting allowing accurate limiting of DC current in the
magnetics, independent of ripple current . User adjustable
slope compensation provides stable operation at duty
cycles up to 90%.
The LT1680 operating frequency is programmable and
can be synchronized up to 200kHz. Minimum off-time
operation provides switch protection. The IC also incorpo-
rates a soft start feature that is gated by both shutdown
and undervoltage lockout conditions.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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High Voltage: Operation Up to 60V Max
High Current: N-Channel Drive Handles Up to
10,000pF Gate Capacitance
Programmable Average Current Limiting
5V Reference Output with 10mA External
Loading Capability
Fixed Frequency Current Mode Operation
Oscillator Synchronizable Up to 200kHz
Undervoltage Lockout with Hysteresis
Programmable Start Inhibit for Power Supply
Sequencing and Protection
User Adjustable Slope Compensation
APPLICATIONS
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High Power Single Board Systems
Distributed Power Converters
Industrial Control Systems
Lead-Acid Battery Back-Up Systems
Automotive and Heavy Equipment
TYPICAL APPLICATION
12V to 48V, 250W Boost
12V
IN
10V TO 15V
24A (DC) R
SENSE
0.005鈩?/div>
C2
1碌F
R
CT
15k
LT1680
1
2
C3 2.2nF
C4 0.22碌F
C
VC
4.7nF
1N914
R
VC
4.7k
3
4
5
6
7
8
C6 0.1碌F
R7
2k
SL/ADJ
C
T
I
AVG
SS
V
C
5V
REF
SYNC
12V
IN
GATE
PGND
SENSE
鈥?/div>
SENSE
+
16
15
14
13
12
11
10
9
R6
75k
+
+
C
CT
1nF
C
IN
680碌F
25V
脳4
C12
1碌F
L1
25碌H
EFFICIENCY (%)
M1
IRFZ44
脳
3
SGND RUN/SHDN
V
FB
V
REF
R9
100k
MBR0520
C11 1nF
D1
MBR20100CT
脳
2
+
L1: Kool M碌
廬
, 18T #14 ON 77314-A7
Kool M碌 IS A REGISTERED TRADEMARK OF MAGNETICS, INC.
C
OUT
680碌F
63V
1680 TA01
脳3
V
OUT
48V
5.2A
U
U
U
Efficiency vs Output Power
100
V
OUT
= 48V
95
90
85
80
75
0
50
150
200
100
OUTPUT POWER (W)
250
1680 TA02
1
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