
CHRONTEL
CH5001A
201-0000-032 Rev 3.0, 6/2/99
9
Power up control:
Seven bits within the CH5001 register map can have their default value determined at the time of power-up, or when
the Reset pin is exercised. This is accomplished by using a high valued pull-down resistor on the C[6:0] pins. At
power-up, the output buffers on these pins are tri-stated, and the pin is pulled high by an internal high impedance
pull-up device. This pull-up can be overridden by connecting a 100K ohm resistor externally to ground. After three
frames, the level at the C[6:0] pins is latched, and seven register bits are set or cleared depending upon the corre-
sponding pin's level. The C[6:0] pins functions are then returned to outputs of the chroma data. The power-up con-
trol affects the following register bits:
Table 2. Power Up Default Control
Pin
Register
Bit
Function
C5
(PUD5*)
22h
3
ADDO
The A/D Direct Output mode can be selected at power up. This may be
desirable for applications which want to use raw data. Logically inverted input
No pull-down resistor - Datapath processing
Pull-down resistor - A/D direct output
C4
(PUD4*)
19h
4
PD
The power down bit can be enabled at power up. This may be desirable in USB
cameras which have power limitations at power up. Logically inverted input
No pull-down resistor - Normal power-up
Pull-down resistor - Power-up in low-power mode
C6
(PUD6)
00h
1
M0
The Mode[0] bit can be used to select between NTSC or PAL output at power
up.
No pull-down resistor - PAL operation
Pull-down resistor - NTSC operation
C[3:0]
(PUD[3:0]*)
1Eh
3:0
ASW[3:0]
The auto-shutter window can be selected at power up. See the register
description for corresponding window selection. Logically inverted inputs
No pull-down resistors gives window "0", Center location