MC1408-8 データシートの表示（PDF） - Philips Electronics
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MC1408-8 Datasheet PDF : 10 Pages
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Philips Semiconductors
8-bit multiplying D/A converter
Product data
MC1408-8
BLOCK DIAGRAM
MSB
LSB
A1
A2
A3
A4
A5
A6
A7
A8
5
6
7
8
9
10
11
12
IO
CURRENT SWITCHES
4
VREF
(+)
14
15
(–)
VREF
R-2R LADDER
BIAS
CURRENT
2
GND
REFERENCE
CURRENT
AMPLIFIER
VEE 3
NPN CURRENT SOURCE PAIR
Figure 2. Block Diagram
13
VCC
16
COMPEN
SL00049
CIRCUIT DESCRIPTION
The MC1408-8 consists of a reference current amplifier, an R-2R
ladder, and 8 high-speed current switches. For many applications,
only a reference resistor and reference voltage need be added.
The switches are non-inverting in operation; therefore, a high state
on the input turns on the specified output current component.
The switch uses current steering for high speed, and a termination
amplifier consisting of an active load gain stage with unity gain
feedback. The termination amplifier holds the parasitic capacitance
of the ladder at a constant voltage during switching, and provides a
low impedance termination of equal voltage for all legs of the ladder.
The R-2R ladder divides the reference amplifier current into
binary-related components, which are fed to the remainder current
which is equal to the least significant bit. This current is shunted to
ground, and the maximum output current is 255/256 of the reference
amplifier current, or 1.992 mA for a 2.0 mA reference amplifier
current if the NPN current source pair is perfectly matched.
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
VCC
VEE
V5 – V12
VO
I14
V14, V15
PD
Positive power supply voltage
Negative power supply voltage
Digital input voltage
Applied output voltage
Reference current
Reference amplifier inputs
Maximum power dissipation, Tamb = 25 °C (still-air)1
N package
D package
Tamb
Operating temperature range
Tstg
Storage temperature range
Tsld
Lead soldering temperature (10 sec)
NOTES:
1. Derate above 25°C, at the following rates:
N package at 11.6 mW/°C;
D package at 8.6 mW/°C
RATING
+5.5
–16.5
0 to VCC
–5.2 to +18
5.0
VEE to VCC
1450
1080
0 to +75
–65 to +150
+230
UNIT
V
V
V
V
mA
mW
mW
°C
°C
°C
2001 Aug 03
3
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