Page 1
Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
© 2001 Elantec Semiconductor, Inc.
EL5481C/EL5482C
General Description
The EL5481C and EL5482C comparators are designed for operation
in single supply and dual supply applications with 5V to 12V between
VS+ and VS-. For single supplies, the inputs can operate from 0.1V
below ground for use in ground sensing applications.
The output side of the comparators can be supplied from a single supply of 2.7V to 5V. The rail-to-rail output swing enables direct
connection of the comparator to both CMOS and TTL logic circuits.
The latch input of the EL5482C can be used to hold the comparator
output value by applying a low logic level to the pin.
The EL5481C is available in the 16-pin SO (0.150") package and the
EL5482C in the 24-pin QSOP package. All are specified for operation
over the full -40°C to +85°C temperature range. Also available are a
single (EL5181C), a dual (EL5281C), and a window comparator
(EL5283C).
1
2
3
4
16
15
14
13
5
6
7
12
11
10
8 9
IND-INA-
IND+
VS+
OUTD
OUTC
VSD
INC+
INC-
INA+
GND
OUTA
OUTB
VS-
INB+
INB-
-+ +++-
- -
EL5481CS
16-Pin SO (0.150")
Pin Configurations
1
2
3
4
16
15
14
13
5
6
7
12
11
9
8
10
20
19
18
17
24
23
22
21
EL5482CU
24-Pin QSOP
- +-+
-+
-+
INA-
INA+
NC
LATCHA
LATCHB
NC
INB+
INB-
GND
VS-
OUTA
OUTB
IND-
IND+
NC
LATCHD
LATCHC
NC
INC+
INC-
VSD
VS+
OUTD
OUTC
Features
• 8ns Typ. Propagation Delay
• 5V to 12V Input Supply
• +2.7V to +5V Output Supply
• True-to-ground Input
• Rail-to-rail Outputs
• Active Low Latch
• Single (EL5181C) Available
• Dual (EL5281C) Available
• Window Available (EL5283C)
• Pin-compatible 4ns Family
Available (EL5185C, EL5285C,
EL5287C, EL5485C & EL5486C)
Applications
• Threshold Detection
• High Speed Sampling Circuits
• High Speed Triggers
• Line Receivers
• PWM Circuits
• High Speed V/F Converters
Ordering Information
Part No. Package
Tape &
Reel Outline #
EL5481CS 16-Pin SO (0.150") - MDP0027
EL5481CS-T7 16-Pin SO (0.150") 7” MDP0027
EL5481CS-T13 16-Pin SO (0.150") 13” MDP0027
EL5482CU 24-Pin QSOP - MDP0040
EL5482CU-T13 24-Pin QSOP 13” MDP0040
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
June 14, 2001
Page 2
2
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Absolute Maximum Ratings (T
A
= 25°C)
Absolute maximum ratings are those values beyond which the device
could be permanently damaged. Absolute maximum ratings are stress
ratings only and functional device operation is not implied.
Analog Supply Voltage (VS+ to VS-) +12.6V
Digital Supply Voltage (VSD to GND) +7V
Differential Input Voltage [(VS-) -0.2V] to [(VS+) +0.2V]
Common-mode Input Voltage [(VS-) -0.2V] to [(VS+) +0.2V]
Latch Input Voltage -0.2V to [(VSD) +0.2V]
Storage Temperature Range -65°C to +150°C
Ambient Operating Temperature -40°C to +85°C
Operating Junction Temperature 125°C
Power Dissipation See Curves
Important Note:
All parameters having Min/Max specifications are guaranteed. Typ values are for information purposes only. Unless otherwise noted, all tests are at the
specified temperature and are pulsed tests, therefore: TJ = TC = TA.
Electrical Characteristics
VS = ±5V, VSD = 5V, RL = 2.3kΩ, CL = 15pF, TA = 25°C, unless otherwise specified.
Parameter Description Condition Min Typ Max Unit
Input
V
OS
Input Offset Voltage V
CM
= 0V, VO = 2.5V 1 4 mV
I
B
Input Bias Current -6 -3.5 µA
C
IN
Input Capacitance 5 pF
I
OS
Input Offset Current V
CM
= 0V, VO = 2.5V -2.5 0.5 2.5 µA
V
CM
Input Voltage Range (VS-) - 0.1 (VS+) - 2.25 V
CMRR Common-mode Rejection Ratio -5.1V < V
CM
< +2.75V 65 90 dB
Output
V
OH
Output High Voltage V
IN
> 250mV VSD - 0.6 VSD - 0.4 V
V
OL
Output Low Voltage V
IN
> 250mV GND + 0.25 GND + 0.5 V
Dynamic Performance
tpd+ Positive Going Delay Time VIN = 1V
P-P
, VOD = 50mV 8 12 ns
tpd- Negative Going Delay Time VIN = 1V
P-P
, VOD = 50mV 8 12 ns
Supply
IS+ Positive Analog Supply Current (per comparator) 7 8.2 mA
IS- Negative Analog Supply Current (per comparator) 5 6.5 mA
I
SD
Digital Supply Current (per comparator) All outputs high 4 5 mA
(per comparator) All outputs low 0.75 1 mA
PSRR Power Supply Rejection Ratio 60 80 dB
Latch - EL5482C Only
V
LH
Latch Input Voltage High 2.0 V
V
LL
Latch Input Voltage Low 0.8 V
I
LH
Latch Input Current High V
LH
= 3.0V -30 -18 µA
I
LL
Latch Input Current Low V
LL
= 0.3V -30 -24 µA
td+ Latch Disable to High Delay 6 ns
td- Latch Disable to Low Delay 6 ns
t
s
Minimum Setup Time 2 ns
t
h
Minimum Hold Time 1 ns
tpw(D) Minimum Latch Disable Pulse Width 10 ns
Page 3
3
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Typical Performance Curves
Positive Supply Current vs Temperature
(per comparator)
7.15
7.1
7.05
7
6.95
6.9
6.85
6.8
6.75
6.7
-50 -30 -10 10 30 50 70 90
Temperature (°C)
I
S
+ (mA)
Negative Supply Current vs Temperature
(per comparator)
-4.4
-4.5
-4.6
-4.7
-4.8
-4.9
-5
-5.1
-5.2
-50 -30 -10 10 30 50 70 90
Temperature (°C)
I
S
- (mA)
Input Bias Current vs Temperature
6
5
4
3
2
1
0
-50 -30 -10 10 30 50 70 90
Temperature (°C)
IB (µA)
Offset Voltage vs Temperature
0.7
0.6
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-50 -30 -10 10 30 50 70 90
Temperature (°C)
V
OS
(mV)
0.5
Negative Supply Current vs Negative Supply
Voltage (per comparator)
5.5
3
5
3.5
4.5
4
0 71 2 3 4 5 6
VS- (V)
I
S
- (mA)
7
0
5
1
3
2
I
S
+ (mA)
Positive Supply Current vs Supply Voltage
(per comparator)
0 71 2 3 4 5 6
VS+ (V)
6
4
VS-=-5V
VSD=5V
VIN=50mV
TA=25°C
VS+=5V
VSD=5V
VIN=50mV
TA=25°C
Page 4
4
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Typical Performance Curves
Propagation Delay vs Supply Voltage
10
9.5
8.5
7.5
7
6.5
6
5.5
5
9
8
4 4.5 5 5.5 6
±VS (V)
Delay Time (ns)
Tpd+
Tpd-
VSD=VS+
VIN=1V Step
VOD=50mV
RL=2.2kΩ
Propagation Delay vs Overdrive
10
9.5
8.5
8
7.5
7
6.5
6
9
0 0.2 0.6 1 1.2 1.6 2
VOD (V)
Delay Time (ns)
Tpd+
TpdVS=±5V
VSD=5V
VIN=3V Step
RL=2.2kΩ
0.4 0.8 1.4 1.8
Propagation Delay vs Overdrive
11
10.5
9.5
9
8.5
8
7.5
7
10
0 0.5 1 2 3
VOD (V)
Delay Time (ns)
Tpd+
Tpd-
VS=±5V
VSD=5V
RL=2.2kΩ
VIN=5V Step
1.5 2.5
Propagation Delay vs Source Resistance
20
18
14
12
10
8
6
4
16
0 0.2 0.4 1 1.6
Source Resistance (kΩ)
Delay Time (ns)
Tpd+
Tpd-
0.6 1.41.20.8
VS=±5V
VSD=5V
RL=2.2kΩ
VIN=1V Step
VOD=50mV
Propagation Delay vs Overdrive
10
9.5
8.5
7.5
7
6.5
6
5.5
5
9
8
0 100 200 300 400 500 600
VOD (mV)
Delay Time (ns)
Tpd+
Tpd-
VS=±5V
VSD=5V
VIN=1V Step
RL=2.2kΩ
Propagation Delay vs Load Capacitance
12
10
9
8
7
6
11
0 20 40 60 80 100 120
C
LOAD
(pF)
Delay Time (ns)
Tpd+
Tpd-
VS=±5V
VSD=5V
RL=2.2kΩ
VIN=1V Step
VOD=50mV
Page 5
5
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Typical Performance Curves
0 102 4 6
Load Current (mA)
Output Low Voltage vs Load Current
0.31
0.15
0.27
Output Low Voltage (V)
8
0.23
0.19
VS=±5V
VSD=5V
VIN=-50mV
0 102 4 6
Load Current (mA)
8
Output High Voltage vs Load Current
4.75
4.3
4.7
Output High Voltage (V)
4.65
4.6
4.55
4.5
4.45
4.4
4.35
VS=±5V
VSD=5V
VIN=50mV
1087mW
Q
S
O
P
2
4
1
1
5
°
C
/
W
Power Dissipation vs Ambient Temperature
1.4
0
1
0.6
0.4
0.2
Power Dissipation (W)
1.2
0.8
0 125100755025
Ambient Temperature (°C)
15085
909mW
S
O
1
6
θ
J
A
=
1
1
0
°
C
/
W
2V
VIN=1V
P-P
FIN=30MHz
1V 20ns
VS=±5V
VSD=5V
Output with 30MHz Input
VIN=1V
P-P
2V 2V 20ns
VIN=3V
P-P
FIN=30MHz
VS=±5V
VSD=5V
Output with 30MHz Input
VIN=3V
P-P
V
O
V
IN
V
O
V
IN
TA=-40°C
TA=85°C
TA=25°C
TA=-40°C
TA=85°C
TA=25°C
Digital Supply Current vs Input Switching
Frequency (per comparator)
30
0
25
15
10
5
I
SD
(mA)
20
0 453525155
Frequency (MHz)
5040302010
VSD=5V
VSD=3V
VS=±5V
Page 6
6
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Timing Diagram
Definition of Terms
Term Definition
V
OS
Input Offset Voltage - Voltage applied between the two input terminals to obtain CMOS logic threshold at the output
V
IN
Input Voltage Pulse Amplitude - Usually set to 1V for comparator specifications
V
OD
Input Voltage Overdrive - Usually set to 50mV and in opposite polarity to VIN for comparator specifications
tpd+ Input to Output High Delay - The propagation delay measured from the time the input signal crosses the input offset voltage to the CMOS
logic threshold of an output low to high transition
tpd- Input to Output Low Delay - The propagation delay measured from the time the input signal crosses the input offset voltage to the CMOS
logic threshold of an output high to low transition
td+ Latch Disable to Output High Delay - The propagation delay measured from the latch signal crossing the CMOS threshold in a low to high
transition to the point of the output crossing CMOS threshold in a low to high transition
td- Latch Disable to Output Low Delay - The propagation delay measured from the latch signal crossing the CMOS threshold in a low to high
transition to the point of the output crossing CMOS threshold in a high to low transition
t
s
Minimum Setup Time - The minimum time before the negative transition of the latch signal that an input signal change must be present in
order to be acquired and held at the outputs
t
h
Minimum Hold Time - The minimum time after the negative transition of the latch signal that an input signal must remain unchanged in
order to be acquired and held at the output
tpw (D) Minimum Latch Disable Pulse Width - The minimum time that the latch signal must remain high in order to acquire and hold an input signal
change
V
IN
V
OD
t
h
t
s
tpd-
tpw(D)
td+
Latch
Enable
Input
Latch
Compare
Latch Latch
Compare
Differential
Input
Voltage
Comparator
Output
1.4V
V
OS
2.4V
Page 7
7
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Pin Descriptions
EL5482C
14-Pin
QSOP
EL5481C
16-Pin SO
(0.150") Pin Name Function Equivalent Circuit
1 1 INA- Negative input, channel A
Circuit 1
2 2 INA+ Positive input, channel A (Reference circuit 1)
3,10,15,22 NC Not Connected
4 3 GND Digital ground
5 LATCHA Latch input, channel A
Circuit 2
6 4 OUTA Output, channel A
Circuit 3
7 5 OUTB Output, channel B (Reference circuit 3)
8 LATCHB Latch input, channel B (Reference circuit 2)
9 6 VS- Negative supply voltage
11 7 INB+ Positive input, channel B (Reference circuit 1)
12 8 INB- Negative input, channel B (Reference circuit 1)
13 9 INC- Negative input, channel C (Reference circuit 1)
14 10 INC+ Positive input, channel C (Reference circuit 1)
16 11 VSD Digital supply voltage
17 LATCHC Latch input, channel C (Reference circuit 2)
18 12 OUTC Output, channel C (Reference circuit 3)
19 13 OUTD Output, channel D (Reference circuit 3)
20 LATCHD Latch input, channel D (Reference circuit 2)
21 14 VS+ Positive supply voltage
23 15 IND+ Positive input, channel D (Reference circuit 1)
24 16 IND- Negative input, channel D (Reference circuit 1)
IN+IN-
VS+
VS-
V
SD
VS+
VS-
LATCH
V
SD
VS+
VS-
OUT
Page 8
8
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Applications Information
Power Supplies and Circuit Layout
The EL5481C and EL5482C comparators operate with
single and dual supply with 5V to 12V between VS+ and
VS-. The output side of the comparators is supplied by a
single supply from 2.7V to 5V. The rail to rail output
swing enables direct connection of the comparator to
both CMOS and TTL logic circuits. As with many high
speed devices, the supplies must be well bypassed. Elantec recommends a 4.7µF tantalum in parallel with a
0.1µF ceramic. These should be placed as close as possible to the supply pins. Keep all leads short to reduce
stray capacitance and lead inductance. This will also
minimize unwanted parasitic feedback around the comparator. The device should be soldered directly to the PC
board instead of using a socket. Use a PC board with a
good, unbroken low inductance ground plane. Good
ground plane construction techniques enhance stability
of the comparators.
Input Voltage Considerations
The EL5481C and EL5482C input range is specified
from 0.1V below VS- to 2.25V below VS+. The criterion
for the input limit is that the output still responds correctly to a small differential input signal. The differential
input stage is a pair of PNP transistors, therefore, the
input bias current flows out of the device. When either
input signal falls below the negative input voltage limit,
the parasitic PN junction formed by the substrate and the
base of the PNP will turn on, resulting in a significant
increase of input bias current. If one of the inputs goes
above the positive input voltage limit, the output will
still maintain the correct logic level as long as the other
input stays within the input range. However, the propagation delay will increase. When both inputs are outside
the input voltage range, the output becomes unpredictable. Large differential voltages greater than the supply
voltage should be avoided to prevent damages to the
input stage. Inputs of unused channels should not be left
floating. They should be driven to a known state. For
example, one input can be tied to ground and the other
input can be connected to some voltage reference (like
±100mV) to avoid oscillation in the output due to
unwanted output to input feedback.
Input Slew Rate
Most high speed comparators oscillate when the voltage
of one of the inputs is close to or equal to the voltage on
the other input due to noise or undesirable feedback. For
clean output waveform, the input must meet certain minimum slew rate requirements. In some applications, it
may be helpful to apply some positive feedback (hysteresis) between the output and the positive input. The
hysteresis effectively causes one comparator's input
voltage to move quickly past the other, thus taking the
input out of the region where oscillation occurs. For the
EL5481C and EL5482C, the propagation delay
increases when the input slew rate increases for low
overdrive voltages. With high overdrive voltages, the
propagation delay does not change much with the input
slew rate.
Latch Pin Dynamics
The EL5482C contains a “transparent” latch for each
channel. The latch pin is designed to be driven with
either a TTL or CMOS output. When the latch is connected to a logic high level or left floating, the
comparator is transparent and immediately responds to
the changes at the input terminals. When the latch is
switched to a logic low level, the comparator output
remains latched to its value just before the latch’s highto-low transition. To guarantee data retention, the input
signal must remain the same state at least 1ns (hold time)
after the latch goes low and at least 2ns (setup time)
before the latch goes low. When the latch goes high, the
new data will appear at the output in approximately 6ns
(latch propagation delay). The EL5481C has no latch
pins.
Hysteresis
Hysteresis can be added externally. The following two
methods can be used to add hysteresis.
Page 9
9
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
Inverting comparator with hysteresis:
R3 adds a portion of the output to the threshold set by R
1
and R2. The calculation of the resistor values are as
follows:
Select the threshold voltage VTH and calculate R1 and
R2. The current through R1/R2 bias string must be many
times greater than the input bias current of the
comparator:
Let the hysteresis be VH, and calculate R3:
where:
VO=VSD-0.8V (swing of the output)
Recalculate R2 to maintain the same value of VTH:
Non inverting comparator with hysteresis:
R3 adds a portion of the output to the positive input.
Note that the current through R3 should be much greater
than the input bias current in order to minimize errors.
The calculation of the resistor values as follows:
Pick the value of R1. R1 should be small (less than 1kΩ)
in order to minimize the propagation delay time.
Choose the hysteresis VH and calculate R3:
Check the current through R3 and make sure that it is
much greater than the input bias current as follows:
The above two methods will generate hysteresis of up to
a few hundred millivolts. Beyond that, the impedance of
R3 is low enough to affect the bias string and adjustment
of R1 may be required.
Power Dissipation
When switching at high speeds, the comparator's drive
capability is limited by the rise in junction temperature
caused by the internal power dissipation. For reliable
operation, the junction temperature must be kept below
T
JMAX
(125°C).
An approximate equation for the device power dissipation is as follows. Assume the power dissipation in the
load is very small:
where:
VS is the analog supply voltage from VS+ to VSIS is the analog quiescent supply current per comparator
VSD is the digital supply voltage from VSD to ground
I
SD
is the digital supply current per comparator
N is the number of comparators in the package
ISD strongly depends on the input switching frequency.
Please refer to the performance curve to choose the input
driving frequency. Having obtained the power dissipation, the maximum junction temperature can be
determined as follows:
+
-
R
3
V
IN
V
REF
R
2
R
1
VTHV
REF
R
1
R1R2+
-------------------×=
R
3
V
O
V
H
--------R1( R2)
||
×=
R21V
REF
( VTH)
V
TH
R
1
-----------
÷–
VTH0.5VSD–
R
3
-------------------------------------
+=
+
-
R
3
V
IN
V
REF
R
1
R3V(SD0.8 )
R
1
V
H
--------×–=
I
0.5VSDV
REF
–
R
3
----------------------------------------=
P
DISSVSISVSDISD
) N××+×(=
T
JMAXTMAXΘJAPDISS
×+=
Page 10
10
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
where:
T
MAX
is the maximum ambient temperature
θJA is the thermal resistance of the package
Threshold Detector
The inverting input is connected to a reference voltage
and the non-inverting input is connected to the input. As
the input passes the V
REF
threshold, the comparator's
output changes state. The non-inverting and inverting
inputs may be reversed.
Crystal Oscillator
A simple crystal oscillator using one comparator of an
EL5481C and EL5482C is shown below. The resistors
R1 and R2 set the bias point at the comparator's noninverting input. Resistors R3, R4, and C1 set the inverting input node at an appropriate DC average voltage
based on the output. The crystal's path provides resonant
positive feedback and stable oscillation occurs.
Although the EL5481C and EL5482C will give the correct logic output when an input is outside the common
mode range, additional delays may occur when it is so
operated. Therefore, the DC bias voltages at the inputs
are set about 500mV below the center of the common
mode range and the 200Ω resistor attenuates the feedback to the non-inverting input. The circuit will operate
with most AT-cut crystal from 1MHz to 8MHz over a
2V to 7V supply range. The output duty cycle for this
circuit is roughly 50% at 5V VCC, but it is affected by
the tolerances of the resistors. The duty cycle can be
adjusted by changing VCC value.
+
-
V
IN
V
REF
V
OUT
+
-
200Ω
V
OUT
R
4
R
3
5V
1MHz to
8MHz
2kΩ
C
1
0.01µF
5kΩ
1.5kΩ
2kΩ
R
1
R
2
Page 11
11
EL5481C/EL5482C
Quad 8ns High-Speed Comparators
EL5481C/EL5482C
General Disclaimer
Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes in the circuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any circuits described
herein and makes no representations that they are free from patent infringement.
WARNING - Life Support Policy
Elantec, Inc. products are not authorized for and should not be used
within Life Support Systems without the specific written consent of
Elantec, Inc. Life Support systems are equipment intended to support or sustain life and whose failure to perform when properly used
in accordance with instructions provided can be reasonably
expected to result in significant personal injury or death. Users contemplating application of Elantec, Inc. Products in Life Support
Systems are requested to contact Elantec, Inc. factory headquarters
to establish suitable terms & conditions for these applications. Elantec, Inc.’s warranty is limited to replacement of defective
components and does not cover injury to persons or property or
other consequential damages.
June 14, 2001
Printed in U.S.A.
Elantec Semiconductor, Inc.
675 Trade Zone Blvd.
Milpitas, CA 95035
Telephone: (408) 945-1323
(888) ELANTEC
Fax: (408) 945-9305
European Office: +44-118-977-6020
Japan Technical Center: +81-45-682-5820
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