SN28837
1/2-INCH PAL TIMER
SOCS031B – JULY 1991
Terminal Functions
TERMINAL
NAME
ABIN
I/O
DESCRIPTION
NO.
38
O
Antiblooming in
The levels on these three terminals determine which of the five antiblooming modes is selected:
Mode
ABS2
NC
NC
NC
H
ABS1
ABS0
L
L
H
H
H
Operation
No ABG pulses
2-MHz burst of ABG pulses
1-MHz burst of ABG pulses
1-MHz continuous ABG pulses
2-MHz continuous ABG pulses
ABS0
ABS1
ABS2
21
22
23
I
I
I
0
1
2
3
4
L
H
L
H
H
L
Mode 1 is used for normal operation.
Optical black clamp
BCP1
BCP2
BF
1
2
O
O
O
O
O
O
O
O
O
Optical black clamp
7
Burst flag
CBLK
CLK
6
Composite blank
50
47
3
3.34-MHz clock (factory-test point)
CLK13M
CP1
13-MHz clock (connect to SN28838 color-subcarrier generator for color operation)
Clamp 1 (signal processing)
Clamp 2 (signal processing)
Composite sync
CP2
4
CSYNC
5
Delay select for S1, S2, S3. When E/L is high, the three serial-transfer pulses occur early relative to the
sample-and-holdpulses SH1, SH2, and SH3. When E/L is low, the three serial-transfer pulses occur late
relative to the sample-and-hold pulses.
E/L
19
I
FI
13
41, 60
27
O
Field index
GND
GP
Ground
I
I
Exposure control: GP gates the PS and PI outputs (see the description of GPS)
When GPS is high, the timer operates in the normal-integration-time mode (t = 20 ms) and VD is
int
connected internally to GP. To operate the imager in the variable-integration-time mode, GPS must be
heldlow and a user-defined logic circuit must be inserted between VD and GP to vary the integration time
(see Figure 1).
GPS
26
GT
37
56
57
53
O
O
O
O
TMS3473B parallel-driver MIDSEL input switch
GT1/SH3 is a logic signal for both Y gate 1 of the TL1051 video preprocessor and sample-and-hold
channel 3 of the TL1593 3-channel sample-and-hold circuit.
GT1/SH3
GT2
Y gate 2 for the TL1051 video preprocessor
GT3/SH2 is a logic signal for both Y gate 3 of the TL1051 video preprocessor and sample-and-hold
channel 2 of the TL1593 3-channel sample-and-hold circuit.
GT3/SH2
HCR
HGATE
HIGH
IDP
59
11
25
10
48
I
Horizontal-counter reset
O
I
Decoded H count signal. HGATE is a test point and is not used in normal operation.
Not used (tie high)
O
O
ID pulse (for SECAM operation)
LSW
Line switch (connect to SN28838 for color operation)
15, 30,
35, 46,
NC
No connect
52, 54, 55
PD
PI
49
39
36
O
O
O
Power down. A low-logic level on PD causes the device to enter a low power-consumption mode.
Parallel-image-area gate clock
PS
Parallel-storage-area gate clock
Standby-mode select. When SB is high, normal operation is selected; when SB is low, the power-down
mode is selected.
SB
29
9
I
SCBLK
O
Subcarrier blank (for SECAM applications)
3
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