FB

SW

RT

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

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

1.75V

PWM

C_LIMIT

10 PA

5 PA

TRACK

SAMPLE

and

HOLD

0.5V/A

RAMP GENERATOR

+ 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

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