lm5085sdx National Semiconductor Corporation, lm5085sdx Datasheet - Page 5

• Manufacturer Part Number: lm5085sdx
• Description: 75v Constant On-time Pfet Buck Switching Controller
• Manufacturer: National Semiconductor Corporation

Off-Time
Regulation and Over-Voltage Comparators (FB Pin)
Soft-Start Function
Thermal Shutdown
Thermal Resistance
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
Note 3: V
Note 4: For detailed information on soldering plastic MSOP and LLP packages refer to the Packaging Data Book available from National Semiconductor
Corporation.
Note 5: Tested on a 4 layer JEDEC board. Four vias provided under the exposed pad. See JEDEC standards JESD51-5 and JESD51-7.
Note 6: Operating current and shutdown current do not include the current in the R
Note 7: The tolerance of the minimum on-time (t
variations. A device which has an on-time at the high end of the range will have an off-time that is at the high end of its range.
Symbol
t
t
t
t
OFF(CL1)
OFF(CL2)
OFF(CL3)
OFF(CL4)
V
T
V
T
θ
θ
I
t
HYS
REF
FB
SS
OV
SD
JA
JC
CC
provides self bias for the internal gate drive.
Parameter
Off-time (current limit) (Note 7)
FB regulation threshold
FB over-voltage threshold
FB bias current
Soft-start time
Junction shutdown temperature
Junction shutdown hysteresis
Junction to ambient, 0 LFPM air flow (Note
5)
Junction to case, 0 LFPM air flow (Note 5) MSOP-8 package
ON
-4) and the current limit off-times (t
Conditions
VIN = 12V, V
VIN = 12V, V
VIN = 48V, V
VIN = 48V, V
Measured with respect to V
Junction temperature rising
MSOP-8 package
MSOP-8EP package
LLP-8 package
MSOP-8EP package
LLP-8 package
5
T
resistor.
OFF(CL1)
FB
FB
FB
FB
= 0V
= 1V
= 0V
= 1V
through (t
OFF(CL4)
REF
) track each other over process and temperature
1.225
5.35
1.42
3.89
Min
1.4
16
1.25
Typ
350
170
126
7.9
1.9
5.7
2.5
5.5
9.1
24
10
20
46
54
29
10.84
1.275
www.national.com
Max
3.03
32.4
8.67
4.3
Units
°C/W
°C/W
mV
ms
nA
µs
µs
µs
µs
°C
°C
V