National Semiconductor LMH1983 User Manual - Applying Power to The Board:

LMH1983 Evaluation Kit Users Guide 

Page 3 of 25 

LMH1983 EVALUATION BOARD OVERVIEW 

The following block diagram shows an overview of the LMH1983 evaluation board and 

general location of the main features, which will be discussed in the following sections of 

this manual. 

Applying power to the board: 

The default configuration to apply power is to apply +5V across the top two pins on J8.   

With a jumper on JP17, and on board LDO is used to generate the 3.3V rail that powers 

the circuits on the evaluation board. 

Alternately, JP17 may be removed, and a 3.3V rail may be applied directly to the bottom 

two pins of J8. 

LMH 

1981 

J2 

LMH1983 

Quad 

2:1 

MUX 

VCXO 

X2 

J8

J1 

J3 

J7 

J4 

J6 

J5 

LP 

3878 

Power 

Header 

Analog  

Ref. In BNC 

Status LEDs 

VCXO

X1 

LPF 

CLKout1

SMA 

CLKout4 

SMAs 

CLKout3

SMA 

CLKout2 

SMA 

HVF

inputs

Syncs 

EXT.HVF 

CLK 

(VCXO 

or SMA)

CLK In 

SMA 

Power LEDs 

J9 

USB 

Port