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LM5008EP High Voltage (100V) Step Down Switching Regulator
OBSOLETE
LM5008EP
August 30, 2011
High Voltage (100V) Step Down Switching Regulator
General Description
The LM5008EP Step Down Switching Regulator features all
of the functions needed to implement a low cost, efficient,
Buck bias regulator. This high voltage regulator contains an
100 V N-Channel Buck Switch. The device is easy to imple-
ment and is provided in the MSOP-8 and the thermally en-
hanced LLP-8 packages. The regulator is based on a
hysteretic control scheme using an ON time inversely pro-
portional to V
IN
. This feature allows the operating frequency
to remain relatively constant. The hysteretic control requires
no loop compensation. An intelligent current limit is imple-
mented with forced OFF time, which is inversely proportional
to Vout. This scheme ensures short circuit protection while
providing minimum foldback. Other protection features in-
clude: Thermal Shutdown, V
CC
under-voltage lockout, Gate
drive under-voltage lockout, and Max Duty Cycle limiter
ENHANCED PLASTIC
• Extended Temperature Performance of −40°C to +125°C
• Baseline Control - Single Fab & Assembly Site
• Process Change Notification (PCN)
• Qualification & Reliability Data
• Solder (PbSn) Lead Finish is standard
• Enhanced Diminishing Manufacturing Sources (DMS)
Support
Features
■
■
■
■
■
■
■
■
■
■
■
■
Integrated 100V, N-Channel buck switch
Internal V
CC
regulator
No loop compensation required
Ultra-Fast transient response
On time varies inversely with line voltage
Operating frequency remains constant with varying line
voltage and load current
Adjustable output voltage
Highly efficient operation
Precision internal reference
Low bias current
Intelligent current limit protection
Thermal shutdown
Typical Applications
■
■
■
■
Selected Military Applications
Selected Avionics Applications
Non-Isolated Telecommunication Buck Regulator
Secondary High Voltage Post Regulator
Package
■
MSOP - 8
■
LLP - 8 (4mm x 4mm)
Ordering Information
Part Number
LM5008MMEP
(Note
1, Note 2)
VID Part Number NS Package Number
(Note
3)
V62/06618–01
TBD
MUA08A
TBD
Note 1:
For the following (Enhanced Plastic) version, check for availability: - LM5008MMXEP, LM5008SDEP, LM5008SDXEP.
Note 2:
FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/
mil
Note 3:
Refer to package details under Physical Dimensions
Connection Diagram
20187602
8-Lead MSOP, LLP
© 2011 National Semiconductor Corporation
201876
Print Date/Time: 2011/08/30 23:05:33
www.national.com
201876 Version 2 Revision 4
LM5008EP
Typical Application Circuit and Block Diagram
20187601
www.national.com
201876 Version 2 Revision 4
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Print Date/Time: 2011/08/30 23:05:33
FIGURE 1.
LM5008EP
Pin Descriptions
Pin
1
2
Name
SW
BST
Switching Node
Boost Pin (Boot–strap capacitor input)
Description
Application Information
Power switching node. Connect to the output inductor,
re-circulating diode, and bootstrap capacitor.
An external capacitor is required between the BST
and the SW pins. A 0.01µF ceramic capacitor is
recommended. An internal diode charges the
capacitor from V
CC
.
A resistor between this pin and RTN sets the off-time
when current limit is detected. The off-time is preset
to 35µs if FB = 0V.
Ground for the entire circuit.
This pin is connected to the inverting input of the
internal regulation comparator. The regulation
threshold is 2.5V.
A resistor between this pin and V
IN
sets the switch on
time as a function of V
IN
. The minimum recommended
on time is 400ns at the maximum input voltage. This
pin can be used for remote shutdown.
If an auxiliary voltage is available to raise the voltage
on this pin, above the regulation setpoint (7V), the
internal series pass regulator will shutdown, reducing
the IC power dissipation. Do not exceed 14V. This
voltage provides gate drive power for the internal Buck
switch. An internal diode is provided between this pin
and the BST pin. A local 0.1µF decoupling capacitor
is recommended. Series pass regulator is current
limited to 10mA.
Recommended operating range: 9.5V to 95V.
3
R
CL
Current Limit OFF time set pin
Toff = 10
-5
/ (0.285 + (FB / 6.35 x 10
− 6
x R
CL
))
Ground pin
Feedback input from Regulated Output
4
5
RTN
FB
6
R
ON
/SD
On time set pin
Ton = 1.25 x 10
-10
R
ON
/ V
IN
7
V
CC
Output from the internal high voltage series pass
regulator. Regulated at 7.0V.
8
V
IN
Input voltage
3
201876 Version 2 Revision 4
Print Date/Time: 2011/08/30 23:05:33
www.national.com
LM5008EP
Absolute Maximum Ratings
(Note
4)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V
IN
to GND
BST to GND
SW to GND (Steady State)
ESD Rating (Note
8)
Human Body Model
BST to V
CC
-0.3V to 100V
-0.3V to 114V
-1V
1.5kV
100V
BST to SW
V
CC
to GND
All Other Inputs to GND
Lead Temperature (Soldering 4 sec)
Storage Temperature Range
14V
14V
-0.3 to 7V
200°C
-55°C to +150°C
Operating Ratings
V
IN
Operating Junction Temperature
(Note
4)
9.5V to 95V
−40°C to + 125°C
Electrical Characteristics
Symbol
V
CC
Supply
V
CC
Reg
V
CC
Regulator Output
V
CC
Current Limit
V
CC
undervoltage Lockout
Voltage (V
CC
increasing)
V
CC
Undervoltage Hysteresis
V
CC
UVLO Delay (filter)
I
IN
Operating Current
I
IN
Shutdown Current
Switch Characteristics
Buck Switch Rds(on)
Gate Drive UVLO
Gate Drive UVLO Hysteresis
Current Limit
Current Limit Threshold
Current Limit Response Time
OFF time generator (test 1)
OFF time generator (test 2)
On Time Generator
T
ON
- 1
T
ON
- 2
Remote Shutdown Threshold
Remote Shutdown Hysteresis
Parameter
(Note
10)
Specifications with standard typeface are for T
J
= 25°C, and those with
boldface
type apply over full
Operating Junction Tem-
perature range.
V
IN
= 48V, unless otherwise stated (Note
6).
Conditions
Min
6.6
(Note
7)
Typ
7
9.5
6.3
200
100mV overdrive
Non-Switching, FB = 3V
R
ON
/SD = 0V
I
TEST
= 200mA, (Note
9)
V
BST
− V
SW
Rising
3.4
10
485
76
1.15
4.5
430
0.41
I
switch
Overdrive = 0.1A Time
to Switch Off
FB=0V, R
CL
= 100K
FB=2.3V, R
CL
= 100K
Vin = 10V
Ron = 200K
Vin = 95V
Ron = 200K
Rising
2.15
200
0.40
0.51
400
35
2.56
2.77
300
0.70
35
3.5
420
1.05
0.61
675
150
2.47
5.5
Max
7.4
Units
V
mA
V
mV
µs
µA
µA
Ω
V
mV
A
ns
µs
µs
µs
ns
V
mV
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201876 Version 2 Revision 4
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Print Date/Time: 2011/08/30 23:05:33
