FB
SW
RT
V
IN
BST
SD
5V
S
R
Q
Q
AGND
IS
CLK
+
SS
PRE
3, 4
2
11
7
6
5 8
9
12
10
13, 14
1
SD
Ir
LM5005
SHUTDOWN
STANDBY
7V
REGULATOR
SYNC
SYNC
OSCILLATOR
RAMP OUT
PGND
CLK
CLK
COMP
ERROR
AMP
R3
21k
C3
330p
C11
330p
R7
10
C9
22
C10
150
R6
1.65k
R5
5.11k
L1
33 PH
C7
0.022
C8
0.47
D1
CSHD6-100C
15, 16
19
17, 18
20
THERMAL
SHUTDOWN
UVLO
UVLO
CLK
DIS
V
CC
LEVEL
SHIFT
DRIVER
1.225V
1.225V
0.7V
0.7V
R4
49.9k
C5
0.01
C6
open
R2
OPEN
C12
OPEN
C4
0.01
C2
2.2
C1
2.2
R1
OPEN
7 ± 75V
V
IN
V
IN
1.75V
PWM
C_LIMIT
10 PA
5 PA
V
IN
TRACK
SAMPLE
and
HOLD
0.5V/A
RAMP GENERATOR
Ir = (5 PA x (V
IN
± V
OUT
))
+ 25 PA
LM5005
SNVS397D –SEPTEMBER 2005–REVISED MARCH 2013
www.ti.com
Typical Application Circuit and Block Diagram
Figure 9. Circuit Diagram
Detailed Operating Description
The LM5005 high voltage switching regulator features all of the functions necessary to implement an efficient
high voltage buck regulator using a minimum of external components. This easy to use regulator integrates a
75V N-Channel buck switch with an output current capability of 2.5 Amps. The regulator control method is based
on current mode control utilizing an emulated current ramp. Peak current mode control provides inherent line
feed-forward, cycle-by-cycle current limiting and ease of loop compensation. The use of an emulated control
ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable processing of very small
duty cycles necessary in high input voltage applications. The operating frequency is user programmable from
50kHz to 500kHz. An oscillator synchronization pin allows multiple LM5005 regulators to self synchronize or be
synchronized to an external clock. The output voltage can be set from 1.225V. Fault protection features include,
current limiting, thermal shutdown and remote shutdown capability. The device is available in the HTSSOP
package featuring an exposed pad to aid thermal dissipation.
The functional block diagram and typical application of the LM5005 is shown in Figure 9. The LM5005 can be
applied in numerous applications to efficiently step-down a high unregulated input voltage. The device is well
suited for telecom, industrial and automotive power bus voltage ranges.
8 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated
Product Folder Links: LM5005
