
TMC22091/TMC22191
PRODUCT SPECIFICATION
36
In read mode, the address is accompanied by a HIGH on the 
R/W pin during a falling edge of CS. The data output pins go 
to a low-impedance state t
DOZ
 ns after CS falls. Valid data is 
present on D
7-0
 t
DOM
 after the falling edge of CS. Because 
this port operates asynchronously with the pixel timing, 
there is an uncertainty in this data valid output delay of one 
PXCK period. This uncertainty does not apply to t
DOZ
.
The RESET pin restores the TMC22x91 to field 1 line 1 and 
places the encoder in a power-down state (if HRESET is 
LOW). Bit 4 of the Global Control Register (SRESET) is set 
LOW. All other control words and CLUT contents are left 
unchanged. Returning RESET HIGH synchronizes the inter-
nal clock with PXCK and restores the device outputs to 
active states.
Reading Pixel Data from the D
7-0
 Port
The microprocessor port of the TMC22x91 may be used to 
monitor digital video outputs. The eight MSBs of the up-
sampled and interpolated pixel data that go to the 
COMPOSITE D/A converter can also be accessed via the 
D
7-0
 port. When the Test Control Register is loaded with 28
h
and the Control Register pointer is loaded with 40
h
, the D
7-0
port will output the 8-bit composite pixels synchronous with 
PXCK. To halt the pixel flow from D
7-0
, simply bring CS 
HIGH.
Luminance pixel data may also be read from D
7-0
. In this 
case, the eight MSBs of luminance at the input of the Sync 
and Blank Insert block are monitored. When the Control 
Register pointer is loaded with 60
h
, the D
7-0
 port will output 
8-bit luminance pixels synchronous with respect to PXCK. 
To halt the pixel flow from D
7-0
, bring CS HIGH.
Operational Timing
The TMC22x91 operates in three distinct modes: 
1.
Master mode. The encoder independently produces all 
internal timing and provides digital sync to the host 
controller.
2.
Slave mode. The encoder accepts horizontal and vertical 
sync from the controller and synchronizes the video out-
put accordingly.
3.
Genlock mode. The encoder accepts horizontal and ver-
tical sync from the companion TMC22071 Genlocking 
Video Digitizer, synchronizes itself to the incoming 
video, and provides appropriate H Sync and V Sync to 
the host. It synchronizes Pixel Data input in two ways:
a.
Internal PDC. The encoder internally generates the 
Pixel Data Control (PDC) signal which calls for 
data input from the external pixel source.
External PDC. The encoder receives a PDC signal 
from the host and accepts Pixel Data based on that 
input.
b.
Figure 12. Reset Timing – PCK Synchronization
PXCK
RESET
tSR
tHR
1
2
3
24330A
tSR
Reset Timing
The TMC22x91 operates from a master clock (PXCK) at 
twice the pixel rate. In Master mode, the PCK to PXCK tim-
ing relationship is set on the rising edge of RESET. In Figure 
12, PCK is denoted by odd PXCK counts.
When RESET is taken LOW with sufficient setup time (t
SR
) 
before a rising edge of PXCK, the internal state machines are 
reset and the device is put into a mode as dictated by the Glo-
bal Control Register bits 0 and 4. In Master mode, when the 
RESET pin is taken HIGH, the internal clock timing is estab-
lished. In Slave and Genlock mode, this timing is established 
by VHSYNC and GHSYNC respectively. The first PXCK 
following this RESET rising edge is designated as PXCK 1. 
Where it is significant, reference PXCK timing will be 
shown with numbered rising edges. A designation of 2N 
clocks refers to an even number of PXCK rising edges from 
device reset. If RESET is not shown and clock numbering 
does not refer to 2N, timing is relative to signals shown in 
the diagram only.
Pixel Data Input Timing
PXCK is internally divided by 2 to generate an internal pixel 
clock, PCK which is not accessible from the pins of the 
TMC22x91. To ensure the correct phase relationship 
between PCK and pixel data, PCK is locked to VHSYNC or 
GHSYNC (Slave or Genlock mode, respectively). In Master 
mode, VHSYNC is produced on the rising edge of PCK 
allowing external circuitry to synchronize the generation of 
pixel data and LDV which also operates at the rate of PCK.
The rising edge of LDV clocks the 24-bit pixel data into 
three 8-bit registers while PCK clocks that data through the 
pixel data path within the TMC22x91. It is therefore neces-
sary to meet the set-up and hold timing between pixel data 
and LDV as well as LDV and PCK as shown in Figure 13.