ca3277 Intersil Corporation, ca3277 Datasheet - Page 4

• Manufacturer Part Number: ca3277
• Description: Dual 5v Regulator With Serial Data Buffer Interface For Microcontroller Applications
• Manufacturer: Intersil Corporation

Applications
Other functions of the CA3277 include a Data Comparator
and Current Multiplier for use as interface buffers to transfer
serial data at higher level logic to and from a remote host
microcontroller. The OUT1 5V Standby Supply provides
power to the local microcontroller which interfaces to the
CA3277 interface buffers at a 5V logic level. As shown in
Figure 1, the DATA IN input of the Data Comparator receives
serial data referenced to the BATT voltage level. The output
of the Data Comparator is 5V CMOS compatible logic and is
connected to the RDI (remote data input) terminal of the
microcontroller. The TDO (data out) output of the microcon-
troller is connected to the Current Multiplier input of the
CA3277.
Current Multiplier - The Current Multiplier, with internal cir-
cuitry shown in Figure 2, receives data from the
microcontroller in the form of an open drain or gate switched
output driving a 22K
Input at pin 10 (CUR IN). The input stage of the Current Mul-
tiplier is a current mirror amplifier which is internally
connected to the 5V regulated OUT1 voltage source. The
output stage of the Current Multiplier is a current mirror
amplifier referenced to GND and has an open collector
Current Output at pin 9 (CUR OUT), with a minimum drive
capability of 35mA. The Current Multiplier output load is
SUPPLY IN
FIGURE 1. TYPICAL APPLICATION CIRCUIT OF THE CA3277 DUAL 5V REGULATOR WITH MICROCONTROLLER AND SERIAL
UNREG
IGN IN
150 H
C1
0.1 F
L1
DATA BUFFER INTERFACE TO A REMOTE HOST
DISPLAY OR
NOTE: DATA IN and CUR OUT are remote/host Serial Data Communication Buffers. Typical Remote Source
CONTROL
330
OUTPUT
+5V
220
R1
Impedance for DATA IN is 1k . Typical Remote Load for CUR OUT is 250
200 F
CUR OUT
resistor load in series to the Current
DATA IN
C2
IGN IN
BATT
OUT2
TO
CURRENT
(V
CA3277
6V
AMP
BATT
22k
CUR
I
R4
DATA
IN
-2.9V)
TDO
COMP
IGNITION
5V MICROCONTROLLER
COMP
DATA
OUT
RDI SENSE
OUT
IGN
OVR-TEMP
LOW VOLT
SHTDWN
BANDGAP
OVR-VOLT
SHTDWN
SHTDWN
ENABLE
IN
REF
(OUT2)
OUT2
CA3277
CONTROL
EN
OUT
7-42
BUS
normally connected via resistive loading to the BATT voltage
supply level. As such, the microcontroller transmits data out
(TDO output) to the input of the CA3277 Current Multiplier
which amplifies and translates the signal back to the voltage
reference level of the BATT power supply input. When
driving a similar remote CA3277, the voltage drop from the
BATT input line switches the Data Comparator which
provides serial data to the RDI input of the remote microcon-
troller. The nominal current gain of the Current Multiplier is
100X.
The application use of the Current Multiplier is not limited to
digital serial data transfer. The Current Multiplier is an
independent function and is open to use for other purposes,
including linear signal amplification, sensor output amplifica-
tion and current controlled threshold switching. The current
output terminal, CUR OUT may be externally load-
connected to OUT1, OUT2, BATT or any other power supply
level up to the maximum ratings given for the BATT input
terminal. It is important to note that some applied uses of the
Current Multiplier may contribute significant on-chip power
dissipation. A nominal current mirror input drive of 200 A will
provide sufficient drive to switch a 250
input of the data comparator. As such, the quiescent OFF
condition of the Data comparator should be in the High state.
GND
0.47 F
C3
AND OUTPUT
AND OUTPUT
ERROR AMP
ERROR AMP
CONTROL
LOW VOLT
CONTROL
CRST
RESET
RESET VDD
VSS
RESET
FB
FB
C4
0.01 F
47K
R5
OUT1
OUT2
0.1 F
0.1 F
C5
C7
MEMORY
CMOS
+5V
resistor load at the
C6
22 F
C8
100 F
+5V ENABLE
STANDBY
SWITCHED
OUTPUT
OUTPUT
+5V