LTC4253/LTC4253A
32
425353aff
For more information www.linear.com/4253
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
APPLICATIONS INFORMATION
The peak power at the fault current limit occurs at the supply
overvoltage threshold. The fault current limited power is:
V
SUPPLY
( )
R
S
• V
ACL
−(V
SUPPLY
− V
Z
) •
R4
R3
(18)
Circuit Breaker with Foldback Current Limit
Figure 17 shows the LTC4253A in a foldback current limit
application. When V
OUT
is shorted to the –48V RTN supply,
current flows through resistors R3 and R4. This results in
a voltage drop across R4 and a corresponding reduction
in voltage drop across the sense resistor, R
S
, as the ACL
amplifier servos the sense voltage between the SENSE and
V
EE
pins to about 60mV. The short-circuit current through
RS reduces as the V
OUT
voltage increases during an output
short-circuit condition. Without foldback current limiting
resistor R4, the current is limited to 3A during analog
current limit. With R4, the short-circuit current is limited
to 0.5A when V
OUT
is shorted to 71V.
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
GN16 (SSOP) 0204
1 2
3
4
5
6
7
8
.229 – .244
(5.817 – 6.198)
.150 – .157**
(3.810 – 3.988)
16
15
14
13
.189 – .196*
(4.801 – 4.978)
12 11 10
9
.016 – .050
(0.406 – 1.270)
.015 ±.004
(0.38 ±0.10)
× 45°
0° – 8° TYP
.007 – .0098
(0.178 – 0.249)
.0532 – .0688
(1.35 – 1.75)
.008 – .012
(0.203 – 0.305)
TYP
.004 – .0098
(0.102 – 0.249)
.0250
(0.635)
BSC
.009
(0.229)
REF
.254 MIN
RECOMMENDED SOLDER PAD LAYOUT
.150 – .165
.0250 BSC.0165 ±.0015
.045 ±.005
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
INCHES
(MILLIMETERS)
NOTE:
1. CONTROLLING DIMENSION: INCHES
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
