
PCM78
3
PIN
NAME
I/O
DESCRIPTION
1
Analog In
–V
MSB Adjust
+V
No Connection
Comparator Common
MSB
BTC/BOB Select
Status
Clock Out
I
I
I
I
Analog Signal Input (1.5k
impedance).
Analog power supply (–5V to –15V).
Internal adjustment point to allow adjustment of MSB major carry.
Power connection for comparator (+5V).
No internal connection.
Comparator common connection. Connect to ground.
Parallel output of bit 1 (MSB) inverted.
Two’s complement (open) or straight binary (grounded) data output format selection.
Output signal held high until conversion is complete.
Internal clock output generated from RC network on pins 11 and 12 (also present when external clock is used lagging
external clock by ~24ns and same duty cycle).
RC connection point used to generate internal clock. Sets clock high time. See text for details.
RC connection point used to generate internal clock. Sets clock low time. See text for details.
Internal shift register containing the previous conversion result. (Alternate latched data output mode).
Power connection for +5V logic supply.
Primary real-time data output synchronized to clock out.
External clock input point (internal clock must be disabled).
Selects either internal or external clock mode (low = internal; open = external).
Terminates conversion at less than 16 bits (open for 16-bit mode). See text for details.
Starts conversion process (can optionally be generated internally).
Latches previous conversion result for readout (must be issued with the S
OUT2
clock to initiate latch and an internal convert
command).
Used to read out internally latched data from previous conversion.
Digital grounding pin.
Analog supply connection (+5V to +15V).
Voltage output (~2.5V) for optional adjustment of MSB transition.
Reference decoupling point.
Analog grounding pin.
2V reference out. Should not be used except as shown in connection diagram.
Connection point for a capacitor to speed reference settling. See text for details.
2
3
4
5
6
7
8
9
10
—
I
O
I
O
O
11
12
13
14
15
16
17
18
19
20
R
1
C
1
R
2
C
2
S
OUT2
+V
DD
S
External Clock
Int/Ext Clock Select
Short Cycle
Convert Command
S
OUT2
Latch
I
I
O
I
O
I
I
I
I
I
21
22
23
24
25
26
27
28
S
Clock
Digital Common
+V
CC
V
Reference Decouple
Analog Common
Reference Out
Speed Up
I
I
I
O
I
I
O
I
NOTE: Analog and digital commons are connected internally.
PIN ASSIGNMENTS
ABSOLUTE MAXIMUM RATINGS
+V
CC
to Analog Common .........................................................0 to +16.5V
–V
CC
to Analog Common .........................................................0 to –16.5V
–V
DD
to Analog Common ..............................................................0 to +7V
Analog Common to Digital Common.................................................
±
0.5V
Logic Inputs to Digital Common ................................. –0.3V to V
DD
+ 0.5V
Analog Inputs to Analog Common ..................................................
±
16.5V
Lead Temperature (soldering, 10s)................................................ +300
°
C
Stresses above these ratings may permanently damage the device.
DIGITAL OUTPUT
ANALOG INPUT
CONDITION
BTC
BOB
+2.999908V
–3.000000V
0.000000V
–0.000092V
+ Full Scale
–Full Scale
Bipolar Zero
Zero-1 LSB
7FFF Hex
8000 Hex
0000 Hex
FFFF Hex
FFFF Hex
0000 Hex
8000 Hex
7FFF Hex
INPUT/OUTPUT RELATIONSHIPS
PACKAGE INFORMATION
PACKAGE DRAWING
NUMBER
(1)
MODEL
PACKAGE
PCM78P
28-Pin Plastic DIP
215
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix D of Burr-Brown IC Data Book.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.