Data Sheet
26185.202
8-BIT SERIAL-INPUT, CONSTANT-
CURRENT LATCHED LED DRIVER
Always order by complete part number, e.g., A6277EA .
The A6277x is specifically designed for LED-display applications.
Each BiCMOS device includes an 8-bit CMOS shift register, accompa-
nying data latches, and eight npn constant-current sink drivers. Two
package styles and two operating temperature ranges are available.
The CMOS shift register and latches allow direct interfacing with
microprocessor-based systems. With a 5 V logic supply, typical serial
data-input rates are up to 20 MHz. The LED drive current is deter-
mined by the user's selection of a single resistor. A CMOS serial data
output permits cascade connections in applications requiring additional
drive lines. For inter-digit blanking, all output drivers can be disabled
with an ENABLE input high. In addition, a HIGH/LOW function
enables full selected current with the application of a logic low, or 50%
selected current with the application of a logic high.
The first character of the part number suffix determines the device
operating temperature range. Suffix `E' is for -40
C to +85C, and
suffix `S' is -20
C to +85C. Two package styles are provided for
through-hole DIP (suffix `A') or surface-mount SOIC (suffix `LW')
applications. The copper lead frame and low logic-power dissipation
allow the dual in-line package to sink 122 mA through all outputs
continuously over the operating temperature range (1.0 V drop,
+85
C).
Note that the A6277EA (DIP) and the A6277ELW
(SOIC) are electrically identical and share a
common terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
DD
...................... 7.0 V
Output Voltage Range,
V
O
............................ -0.5 V to +24 V
Output Current, I
O
....................... 150 mA
Input Voltage Range,
V
I
.................... -0.4 V to V
DD
+ 0.4 V
Package Power Dissipation,
P
D
..................................... See Graph
Operating Temperature Range, T
A
Suffix `S-' ................ -20
C to +85
C
Suffix `E-' ................ -40
C to +85
C
Storage Temperature Range,
T
S
........................... -55
C to +150
C
Caution: These CMOS devices have input
static protection (Class 2) but are still suscep-
tible to damage if exposed to extremely high
static electrical charges.
6277
PRELIMINARY INFORMATION
(Subject to change without notice)
July 20, 2000
FEATURES
I To 150 mA Constant-Current Outputs
I 24 V Outputs
I Under-Voltage Lockout
I Low-Power CMOS Logic and Latches
I High Data Input Rate
I Similar to Toshiba TD62715FN
I High/Low Output Current Function
A6277ELW
REGISTER
LATCHES
5
10
11
12
13
14
15
6
7
8
9
16
POWER
GROUND
POWER
GROUND
HIGH/LOW
(CURRENT)
OUT
1
OUT
2
Dwg. PP-029-17A
OUT
0
OUT
4
OUT
6
OUT
5
OUT
3
OUT
7
LOGIC
GROUND
1
2
3
17
19
4
18
20
SERIAL
DATA OUT
LOGIC
SUPPLY
SERIAL
DATA IN
OUTPUT
ENABLE
LATCH
ENABLE
CLOCK
CK
V
DD
OE
R
EXT
I
REGULATOR
L
O
SUB
SUB
SERIAL
DATA OUT
2
1
FF
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
6277
8-BIT SERIAL-INPUT,
CONSTANT-CURRENT
LATCHED LED DRIVER
2
Copyright 2000, Allegro MicroSystems, Inc.
50
75
100
125
150
2.5
0.5
0
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
AMBIENT TEMPERATURE IN
C
2.0
1.5
1.0
25
SUFFIX 'A', R = 55
C/W
JA
Dwg. GP-018-1
SUFFIX 'LW', R = 70
C/W
JA
FUNCTIONAL BLOCK DIAGRAM
MOS
BIPOLAR
LOGIC
GROUND
LATCH
ENABLE
OUTPUT ENABLE
(ACTIVE LOW)
SERIAL DATA
OUT
CLOCK
SERIAL
DATA IN
SERIAL-PARALLEL SHIFT REGISTER
LATCHES
V
DD
LOGIC
SUPPLY
R
OUT
0
OUT
1
Dwg. FP-013-7
OUT
2
OUT
N
I
REGULATOR
O
UVLO
POWER
GROUND
POWER
GROUND
SUB
HIGH/LOW
(CURRENT)
FF
SERIAL DATA
OUT
EXT
1
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
6277
8-BIT SERIAL-INPUT,
CONSTANT-CURRENT
LATCHED LED DRIVER
4
ELECTRICAL CHARACTERISTICS at T
A
= +25
C, V
H/L
= V
DD
= 5 V (unless otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Supply Voltage Range
V
DD
Operating
4.5
5.0
5.5
V
Under-Voltage Lockout
V
DD(UV)
V
DD
= 0 to 5 V
3.4
4.0
V
Output Current
I
O
V
CE
= 1.0 V, R
EXT
= 160
100
120
140
mA
(any single output)
V
CE
= 0.4 V, R
EXT
= 470
34
42
48
mA
Output Current Matching
I
O
0.4 V
V
CE(A)
= V
CE(B)
1.0 V:
(difference between any
R
EXT
= 160
1.5
6.0
%
two outputs at same V
CE
)
R
EXT
= 470
1.5
6.0
%
Output Leakage Current
I
CEX
V
OH
= 20 V
1.0
5.0
A
Logic Input Voltage
V
IH
0.7V
DD
V
V
IL
0.3V
DD
V
SERIAL DATA OUT Voltage
V
OL
I
OL
= 1.0 mA
0.4
V
(SDO
1
& SDO
2
)
V
OH
I
OH
= -1.0 mA
4.6
V
Input Resistance
R
I
ENABLE input, pull up
150
300
600
k
LATCH & HIGH/LOW inputs, pull down
100
270
400
k
Supply Current
I
DD(OFF)
R
EXT
= open, V
OE
= 5 V
0.8
1.6
mA
R
EXT
= 470
, V
OE
= 5 V
3.5
6.5
9.5
mA
R
EXT
= 160
, V
OE
= 5 V
14
17
22
mA
I
DD(ON)
R
EXT
= 470
, V
OE
= 0 V
5.0
10
15
mA
R
EXT
= 160
, V
OE
= 0 V
20
27
40
mA
Typical Data is at V
DD
= 5 V and is for design information only.
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