Datasheet
3x2
Video Clock
Crosspoint
External Loop Filter and VCXO
VC_LPF
XOin-
CLKout2-
NO_LOCK
Fin
Hin
Vin
SDA
SCL
CLKout2+
CLKout1+
CLKout3-
CLKout3+
CLKout4-
CLKout4+
CLKout1-
Device
Control and
Registers
ADDR
XOin+
= Device pins
NO_REF
27.0
(13.5)
MHz
V
DD
/2
PLL3
3G(HD)/1.001
Video Clock
PLL2
3G(HD)
Video Clock
I
2
C Interface
PLL1
Genlock PLL
27 MHz
VCXO
148.5
(74.25)
MHz
PLL4
Audio Clock
148.35,
(74.176)
MHz
98.304 MHz,
others*
In1
In2
In3
Out2
Out3
Vc(Genlock)
Vc(Freerun)
10-Bit SAR
ADC
Input Format
and Polarity
Detection
DAC
Ref
Fbk
* Audio Clock PLL supports 98.304/2
X
MHz, where X=0-15
I
2
C Address Options: 0x65h-67h
NO_ALIGN
TOF1
Fout1
Fout2
Fout3
Fout4
(Osc In)
MUX
27 MHz_Osc
AFS/Word
LMH1983
SNLS309G –APRIL 2010–REVISED JANUARY 2011
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
The dual-stage PLL architecture integrates four PLLs with three on-chip VCOs. The first stage (PLL1) uses an
external low-noise 27 MHz VCXO with narrow loop bandwidth to provide a clean reference clock for the next
stage. The second stage (PLL2, 3, 4) consists of three parallel VCO PLLs for simultaneous generation of the
major digital A/V clock fundamental rates, including 148.5 MHz, 148.5/1.001 MHz, and 98.304 MHz (4x 24.576
MHz). Each PLL can generate a clock and a timing pulse to indicate Top Of Frame (TOF).
When locked to reference, an internal 10-bit ADC will track the loop filter control voltage. When a loss of
reference (LOR) occurs, the LMH1983 can be programmed to hold the control voltage to maintain output
accuracy within ±0.5 ppm (typ.) of the previous reference. The LMH1983 can be configured to re-synchronize to
a previous reference with glitch-less operation.
The LMH1983 is offered in a space-saving 6 mm x 6 mm 40-pin WQFN package.
FUNCTIONAL BLOCK DIAGRAM
2 Submit Documentation Feedback Copyright © 2010–2011, Texas Instruments Incorporated
Product Folder Links: LMH1983