OUT(FB)

2

3

4

5

6

7

8

1

SET

FB

GND(CP)

CP

EN

IN(CP)

VIN

VOUT

GND

GND

CCP

10 nF

COUT

10 PF

R1

47.5k

R2

15.0k

LP38788

GND

IN

IN

OUT

OUT

9

10

11

12

VEN

DAP

5.00V

5.50V

CIN

1 PF

MLCC

+

(1.20V)

(5.00V)

LP38788, LP38788-ADJ

SNVS802B – APRIL 2012 – REVISED OCTOBER 2012

www.ti.com

MOUNTING THE LLP PACKAGE

The SDA12B (No Pullback) 12-Lead LLP package requires specific mounting techniques that are detailed in AN-

1187 (Literature Number: snoa401q). Referring to the section PCB Design Recommendations in AN-1187

(Page 5), it should be noted that the pad style that should be used with the SDA12B LLP package is the NSMD

(non-solder mask defined) type. Additionally, it is recommended the PCB terminal pads to be 0.2 mm longer than

the package pads to create a solder fillet to improve reliability and inspection.

The thermal dissipation of the LLP package is directly related to the printed circuit board construction and the

amount of additional copper area connected to the DAP.

The DAP (exposed pad) on the bottom of the LLP package is connected to the die substrate with a conductive

die attach adhesive. The DAP has no direct electrical (wire) connection to any of the twelve pins. There is a

parasitic PN junction between the die substrate and the device ground. As such, it is strongly recommend that

the DAP be connected directly to the ground at device leads 6 and 7 (i.e. GND). Alternately, but not

recommended, the DAP may be left floating (i.e. no electrical connection). The DAP must not be connected to

any potential other than ground.

For the LP38788 in the SDA12B 12-Lead LLP package, the junction-to-case thermal resistance rating,

θJC, is

5°C/W, where the case is on the bottom of the package at the center of the DAP.

The junction-to-ambient thermal performance for the LP38788SD in the SDA12B 12-Lead LLP package, using

the JEDEC JESD51 standards, is summarized in the following table:

LP38788SD-ADJ (LLP-12) Thermal Performance

Board

Thermal

θJA

PSIJB

θJC

Type

Vias

JEDEC

2-Layer

None

138°C/W

45.9°C/W

5°C/W

JESD 51-3

1

51°C/W

26.1°C/W

2

45°C/W

24.7°C/W

JEDEC

4-Layer

4

39°C/W

18.0°C/W

5°C/W

JESD 51-7

6

36°C/W

14.9°C/W

8

34°C/W

13.2°C/W

Typical Applications

Figure 2. Typical Application, VOUT= 5.0V

10

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