MAXIM MAX4090EXT-T

19-2813; Rev 2; 8/04
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
The MAX4090 3V/5V, 6dB video buffer with sync-tip
clamp, and low-power shutdown mode is available in
tiny SOT23 and SC70 packages. The MAX4090 is
designed to drive DC-coupled, 150Ω back-terminated
video loads in portable video applications such as digital still cams, portable DVD players, digital camcorders,
PDAs, video-enabled cell phones, portable game systems, and notebook computers. The input clamp positions the video waveform at the output and allows the
MAX4090 to be used as a DC-coupled output driver.
The MAX4090 operates from a single 2.7V to 5.5V supply and consumes only 6.5mA of supply current. The
low-power shutdown mode reduces the supply current
to 150nA, making the MAX4090 ideal for low-voltage,
battery-powered video applications.
Features
♦ Single-Supply Operation from 2.7V to 5.5V
♦ Input Sync-Tip Clamp
♦ DC-Coupled Output
♦ Low-Power Shutdown Mode Reduces Supply
Current to 150nA
♦ Available in Space-Saving SOT23 and SC70
Packages
The MAX4090 is available in tiny 6-pin SOT23 and
SC70 packages and is specified over the extended
-40°C to +85°C temperature range.
Applications
Ordering Information
Portable Video/Game Systems/DVD Players
Digital Camcorders/Televisions/Still Cameras
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
PDAs
MAX4090EXT-T
-40°C to +85°C
6 SC70-6
ABM
Video-Enabled Cell Phones
MAX4090EUT-T
-40°C to +85°C
6 SOT23-6
ABOX
Notebook Computers
Portable/Flat-Panel Displays
Block Diagram
Pin Configuration
TOP VIEW
VCC
TOP VIEW
MAX4090
OUT 1
6
FB
IN
OUT
GND 2
MAX4090
5
SHDN
4
VCC
2.3kΩ
CLAMP
FB
IN 3
580Ω
780Ω
1.2kΩ
SC70/SOT23
SHDN
GND
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX4090
General Description
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
ABSOLUTE MAXIMUM RATINGS
VCC to GND ............................................................. -0.3V to +6V
OUT, FB, SHDN to GND............................ -0.3V to (VCC + 0.3V)
IN to GND (Note 1) ................................... VCLP to (VCC + 0.3V)
IN Short-Circuit Duration from -0.3V to VCLP ........................1min
Output Short-Circuit Duration to VCC or GND .......... Continuous
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C) ...........695mW
6-Pin SC70 (derate 3.1mW/°C above +70°C) .............245mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
Note 1: VCLP is the input clamp voltage as defined in the DC Electrical Characteristics table.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = 3.0V, GND = 0V, CIN = 0.1µF from IN to GND, RL = infinity to GND, FB shorted to OUT, SHDN = 3.0V, TA = -40°C to +85°C.
Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER
Supply Voltage Range
SYMBOL
VCC
CONDITIONS
Guaranteed by PSRR
MIN
2.7
6.5
10
ISHDN
SHDN = 0V
Input Clamp Voltage
VCLP
Input referred
0.27
Inferred from voltage gain (Note 3)
VCLP
Input Resistance
Voltage Gain
Power-Supply Rejection Ratio
VIN = 1.45V
AV
2
80
VCC = 3V
2.55
2.7
VCC = 5V
4.3
4.6
VOL
RL = 150Ω to GND
ISC
SHDN Logic-Low Threshold
VIL
SHDN Logic-High Threshold
VIH
SHDN Input Current
IIH
Shutdown Output Impedance
2
ROUT
(Disabled)
1.45
V
35
µA
3
60
Output Voltage Low Swing
Output Short-Circuit Current
V
1.9
RL = 150Ω to GND
IOUT
µA
0.47
RL = 150Ω, 0.5V < VIN < 1.45V (Note 4)
VOH
Output Current
1
0.38
2.7V < VCC < 5.5V
Output Voltage High Swing
VCLP
Sourcing, RL = 20Ω to GND
45
85
Sinking, RL = 20Ω to VCC
40
85
OUT shorted to VCC or GND
MΩ
2.1
V/V
dB
V
0.47
V
mA
110
mA
VCC x 0.3
VCC x 0.7
V
V
0.003
SHDN = 0V
mA
0.15
22.5
VCLP + 0.5V < VIN < VCLP + 1V
PSRR
V
VCC = 5V
Shutdown Supply Current
VIN
5.5
10
VIN = VCLP
IBIAS
UNITS
6.5
ICC
Input Bias Current
MAX
VCC = 3V
Quiescent Supply Current
Input Voltage Range
TYP
At DC
4
At 3.58MHz or
4.43MHz
2
_______________________________________________________________________________________
1
µA
kΩ
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
(VCC = 3.0V, GND = 0V, FB shorted to OUT, CIN = 0.1µF, RIN = 75Ω to GND, RL = 150Ω to GND, SHDN = VCC, TA = +25°C, unless
otherwise noted.)
PARAMETER
Small-Signal -3dB Bandwidth
Large-Signal -3dB Bandwidth
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
BWSS
VOUT = 100mVP-P
55
MHz
BWLS
VOUT = 2VP-P
45
MHz
Small-Signal 0.1dB Gain Flatness
BW0.1dBSS VOUT = 100mVP-P
25
MHz
Large-Signal 0.1dB Gain Flatness
BW0.1dBLS VOUT = 2VP-P
SR
VOUT = 2V step
17
MHz
275
V/µs
Slew Rate
Settling Time to 0.1%
tS
VOUT = 2V step
25
ns
50
dB
2.5
Ω
Power-Supply Rejection Ratio
PSRR
f = 100kHz
Output Impedance
ZOUT
f = 5MHz
Differential Gain
DG
NTSC
Differential Phase
DP
NTSC
VCC = 3V
1
VCC = 5V
0.5
VCC = 3V
0.8
VCC = 5V
0.5
Group Delay
D/dT
f = 3.58MHz or 4.43MHz
20
Peak Signal to RMS Noise
SNR
VIN = 1VP-P, 10MHz BW
65
CIN = 0.1µF (Note 4)
2
Droop
%
Degrees
ns
dB
3
%
SHDN Enable Time
tON
VIN = VCLP + 1V, SHDN = 3V, VOUT settled
to within 1% of the final voltage
250
ns
SHDN Disable Time
tOFF
VIN = VCLP + 1V, SHDN = 0V, VOUT settled
to below 1% of the output voltage
50
ns
Note 2: All devices are 100% production tested at TA = +25°C. Specifications over temperature limits are guaranteed by design.
Note 3: Voltage gain (AV) is referenced to the clamp voltage, i.e., an input voltage of VIN = VCLP + VI would produce an output voltage of VOUT = VCLP + AV x VI.
Note 4: Droop is guaranteed by the Input Bias Current specification.
_______________________________________________________________________________________
3
MAX4090
AC ELECTRICAL CHARACTERISTICS
Typical Operating Characteristics
(VCC = 3.0V, GND = 0V, FB shorted to OUT, CIN = 0.1µF, RIN = 75Ω to GND, RL = 150Ω to GND, SHDN = VCC, TA = +25°C, unless
otherwise noted.)
SMALL-SIGNAL GAIN
vs. FREQUENCY
SMALL-SIGNAL GAIN FLATNESS
vs. FREQUENCY
1
0.2
0.1
-2
-0.3
-0.4
100k
1M
-0.5
-0.6
10M
100M
100k
100M
100k
1
0.2
0.1
-0.4
-4
100k
1M
-5
-6
10M
GAIN (dB)
-2
-3
AV = 2
VCC = 5V
VOUT = 100mVP-P
0
-1
-0.3
100M
100M
10M
MAX4090 toc06
2
0
-0.1
-0.2
-0.3
-0.4
AV = 2
VCC = 3V
VOUT = 2VP-P
100k
-0.5
-0.6
1M
10M
100M
AV = 2
VCC = 3V
VOUT = 2VP-P
100k
1M
100M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
LARGE-SIGNAL GAIN
vs. FREQUENCY
LARGE-SIGNAL GAIN FLATNESS
vs. FREQUENCY
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
1
0.2
0.1
VCC = 3V
-10
-20
-1
-2
-3
PSRR (dB)
0
GAIN (dB)
0
0
-0.1
-0.2
-0.4
-0.5
-0.6
1M
10M
FREQUENCY (Hz)
100M
-30
-40
-50
-0.3
AV = 2
VCC = 5V
VOUT = 2VP-P
MAX4090 toc09
2
MAX4090 toc08
0.3
MAX4090 toc07
3
100k
1M
0.3
MAX4090 toc05
MAX4090 toc04
3
GAIN (dB)
GAIN (dB)
-6
10M
AV = 2
VCC = 5V
VOUT = 100mVP-P
LARGE-SIGNAL GAIN FLATNESS
vs. FREQUENCY
-0.2
-6
1M
-5
LARGE-SIGNAL GAIN
vs. FREQUENCY
0
-5
-4
AV = 2
VCC = 3V
VOUT = 100mVP-P
SMALL-SIGNAL GAIN FLATNESS
vs. FREQUENCY
-0.1
-4
-3
FREQUENCY (Hz)
0.1
-0.6
-2
FREQUENCY (Hz)
0.2
-0.5
-1
FREQUENCY (Hz)
0.3
4
-0.2
-4
AV = 2
VCC = 3V
VOUT = 100mVP-P
0
-0.1
-3
-6
1
GAIN (dB)
-1
-5
2
0
GAIN (dB)
GAIN (dB)
0
3
MAX4090 toc03
2
SMALL-SIGNAL GAIN
vs. FREQUENCY
MAX4090 toc02
0.3
MAX4090 toc01
3
GAIN (dB)
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
-60
AV = 2
VCC = 5V
VOUT = 2VP-P
100k
-70
-80
1M
10M
FREQUENCY (Hz)
100M
10k
100k
1M
FREQUENCY (Hz)
_______________________________________________________________________________________
10M
100M
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
(VCC = 3.0V, GND = 0V, FB shorted to OUT, CIN = 0.1µF, RIN = 75Ω to GND, RL = 150Ω to GND, SHDN = VCC, TA = +25°C, unless
otherwise noted.)
6.75
6.70
-40
-50
-60
0.50
6.65
VCC = 5V
6.60
6.55
6.50
0.30
6.40
-70
0.25
6.35
-80
6.30
100k
1M
100M
10M
0.20
-50
-25
FREQUENCY (Hz)
25
50
75
100
-50
-25
TEMPERATURE (°C)
CLAMP VOLTAGE
vs. TEMPERATURE
2.10
MAX4090 toc13
VCC = 5V
0.55
VCC = 3V
0.40
50
75
100
VOLTAGE GAIN vs. TEMPERATURE
VCC = 5V
2.05
GAIN (V/V)
GAIN (V/V)
0.45
25
2.10
2.05
0.50
0
TEMPERATURE (°C)
VOLTAGE GAIN vs. TEMPERATURE
0.60
VCLAMP (V)
0
MAX4090 toc14
10k
0.40
0.35
VCC = 3V
6.45
0.45
MAX4090 toc15
-30
VCC = 3V
0.55
VCLAMP (V)
SUPPLY CURRENT (mA)
PSRR (dB)
-20
0.60
MAX4090 toc11
VCC = 5V
-10
6.80
MAX4090 toc10
0
CLAMP VOLTAGE
vs. TEMPERATURE
QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
MAX4090 toc12
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
2.00
2.00
0.35
1.95
0.30
1.95
0.25
1.90
0.20
-25
0
25
50
75
0
25
50
75
100
-50
-25
0
25
50
75
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT VOLTAGE HIGH SWING
vs. TEMPERATURE
OUTPUT VOLTAGE HIGH SWING
vs. TEMPERATURE
LARGE-SIGNAL PULSE RESPONSE
VCC = 3V
2.8
2.7
2.6
2.5
2.4
2.3
100
MAX4090 toc18
5.0
MAX4090 toc17
MAX4090 toc16
OUTPUT VOLTAGE HIGH (V)
-25
TEMPERATURE (°C)
3.0
2.9
1.90
-50
100
VCC = 5V
4.9
OUTPUT VOLTAGE HIGH (V)
-50
4.8
VIN
500mV/div
4.7
4.6
4.5
4.4
4.3
2.2
4.2
2.1
4.1
VOUT
1V/div
4.0
2.0
-50
-25
0
25
50
TEMPERATURE (°C)
75
100
-50
-25
0
25
50
75
100
10ns/div
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX4090
Typical Operating Characteristics (continued)
Typical Operating Characteristics (continued)
(VCC = 3.0V, GND = 0V, FB shorted to OUT, CIN = 0.1µF, RIN = 75Ω to GND, RL = 150Ω to GND, SHDN = VCC, TA = +25°C, unless
otherwise noted.)
SMALL-SIGNAL PULSE RESPONSE
DIFFERENTIAL GAIN AND PHASE
MAX4090 toc19
VIN
25mV/div
MAX4090 toc20
DIFFERENTIAL
GAIN (%)
2.0
1.0
0
-1.0
-2.0
0
1
2
3
4
5
6
0
1
2
3
4
5
6
1.0
DIFFERENTIAL
PHASE (°)
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
VOUT
50mV/div
0.5
0
-0.5
-1.0
10ns/div
Typical Application Circuit
Pin Description
PIN
NAME
FUNCTION
1
OUT
Video Output
2
GND
Ground
3
IN
4
VCC
5
SHDN
6
FB
VCC
Video Input
Power-Supply Voltage. Bypass with a 0.1µF
capacitor to ground as close to pin as
possible.
Shutdown. Pull SHDN low to place the
MAX4090 in low-power shutdown mode.
MAX4090
IN
OUT
RIN
RL
CLAMP
Feedback. Connect to OUT.
FB
SHDN
GND
6
_______________________________________________________________________________________
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
The MAX4090 3V/5V, 6dB video buffer with sync-tip
clamp and low-power shutdown mode is available in tiny
SOT23 and SC70 packages. The MAX4090 is designed
to drive DC-coupled, 150Ω back-terminated video loads
in portable video applications such as digital still cams,
portable DVD players, digital camcorders, PDAs, videoenabled cell phones, portable game systems, and notebook computers. The input clamp positions the video
waveform at the output and allows the MAX4090 to be
used as a DC-coupled output driver.
The MAX4090 operates from a single 2.7V to 5.5V supply and consumes only 6.5mA of supply current. The
low-power shutdown mode reduces the supply current
to 150nA, making the MAX4090 ideal for low-voltage,
battery-powered video applications.
The input signal to the MAX4090 is AC-coupled
through a capacitor into an active sync-tip clamp circuit, which places the minimum of the video signal at
approximately 0.38V. The output buffer amplifies the
video signal while still maintaining the 0.38V clamp voltage at the output. For example, if VIN = 0.38V, then
VOUT = 0.38V. If VIN = (0.38V + 1V) = 1.38V, then VOUT
= (0.38V + 2 X (1V)) = 2.38V. The net result is that a 2V
video output signal swings within the usable output
voltage range of the output buffer when VCC = 3V.
Shutdown Mode
The MAX4090 features a low-power shutdown mode
(ISHDN = 150nA) for battery-powered/portable applications. Pulling the SHDN pin high enables the output.
Connecting the SHDN pin to ground (GND) disables
the output and places the MAX4090 into a low-power
shutdown mode.
Applications Information
Input Coupling the MAX4090
The MAX4090 input must be AC-coupled because the
input capacitor stores the clamp voltage. The MAX4090
requires a typical value of 0.1µF for the input clamp to
meet the Line Droop specification. A minimum of a
ceramic capacitor with an X7R temperature coefficient
is recommended to avoid temperature-related problems with Line Droop. For extended temperature operation, such as outdoor applications, or where the
impressed voltage is close to the rated voltage of the
capacitor, a film dielectric is recommended. Increasing
the capacitor value slows the clamp capture time.
Values above 0.5µF should be avoided since they do
not improve the clamp’s performance.
The active sync-tip clamp also requires that the input
impedance seen by the input capacitor be less than
100Ω typically to function properly. This is easily met
by the 75Ω input resistor prior to the input-coupling
capacitor and the back termination from a prior stage.
Insufficient input resistance to ground causes the
MAX4090 to appear to oscillate. Never operate the
MAX4090 in this mode.
Using the MAX4090 with the
Reconstruction Filter
In most video applications, the video signal generated
from the DAC requires a reconstruction filter to smooth
out the signal and attenuate the sampling aliases. The
MAX4090 is a direct DC-coupled output driver, which
can be used after the reconstruction filter to drive the
video signal. The driving load from the video DAC can
be varied from 75Ω to 300Ω. A low input impedance
(<100Ω) is required by the MAX4090 in normal operation, special care must be taken when a reconstruction
filter is used in front of the MAX4090.
For standard video signal, the video passband is about
6MHz and the system oversampling frequency is at
27MHz. Normally, a 9MHz BW lowpass filter can be
used for the reconstruction filter. This section demonstrates the methods to build simple 2nd- and 3rd-order
passive butterworth lowpass filters at the 9MHz cutoff
frequency and the techniques to use them with the
MAX4090 (Figures 1 and 4).
2nd-Order Butterworth Lowpass Filter Realization
Table 1 shows the normalized 2nd-order butterworth
LPF component values at 1rad/s with a source/load
impedance of 1Ω.
With the following equations, the L and C can be calculated for the cutoff frequency at 9MHz. Table 2 shows
the appropriated L and C values for different source/
load impedance, the bench measurement values for
the -3dB BW and attenuation at 27MHz. There is
approximately 20dB attenuation at 27MHz, which effectively attenuates the sampling aliases. The MAX4090
requires low input impedance for stable operation and
it does not like the reactive input impedance. For R1/R2
greater than 100Ω, a series resistor R IS (Figure 1)
Table 1. 2nd Order Butterworth Lowpass
Filter Normalized Values
Rn1 = Rn2 (Ω)
Cn1 (F)
Ln1 (H)
1
1.414
1.414
_______________________________________________________________________________________
7
MAX4090
Detailed Description
3rd-Order Butterworth Lowpass Filter Realization
If more flat passband and more stopband attenuation
are needed, a 3rd-order LPF can be used. The design
procedures are similar to the 2nd-order butterworth
LPF.
Table 3 shows the normalized 3rd-order butterworth
lowpass filter with the cutoff frequency at 1 rad/s and
the stopband frequency at 3 rad/s. Table 4 shows the
appropriated L and C values for different source/load
impedance and the bench measurement values for
-3dB BW and attenuation at 27MHz. The attenuation is
over 40dB at 27MHz. At 6MHz, the attenuation is
approximately 0.6dB for R1 = R2 = 150Ω (Figure 5).
between 20Ω to 100Ω is needed to isolate the input
capacitor (C4) to the filter to prevent the oscillation
problem.
C=
Cn
L R
L= n L
2πfCRL
2πfC
Figure 2 shows the frequency response for R1 = R2 =
150Ω. At 6MHz, the attenuation is about 1.4dB. The
attenuation at 27MHz is about 20dB. Figure 3 shows
the multiburst response for R1 = R2 = 150Ω.
VCC
C7
1µF
2-POLE RECONSTRUCTION LPF
4
RIS
49.9Ω
L1
3.9µH
VIDEO
CURRENT
DAC
C1
150pF
R1
150Ω
C4
0.1µF
VCC
3
IN
OUT
1
R3
75Ω
MAX4090
R2
150Ω
5
FB
SHDN
6
GND
VCC
2
Figure 1. 2nd-Order Butterworth LPF with MAX4090
FREQUENCY RESPONSE
0
-10
VIN
500mV/div
-20
GAIN (dB)
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
-30
VOUT
500mV/div
-40
-50
-60
0.1
1
10
100
10µs/div
FREQUENCY (MHz)
Figure 2. Frequency Response
8
Figure 3. Multiburst Response
_______________________________________________________________________________________
VOUT
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
MAX4090
VCC
3-POLE RECONSTRUCTION LPF
C3
6.8pF
C7
1µF
4
RIS
49.9Ω
L1
4.7µH
VIDEO
CURRENT
DAC
R1
150Ω
C1
120pF
C4
0.1µF
VCC
3
C2
120pF
R2
150Ω
IN
OUT
1
R3
75Ω
VOUT
MAX4090
5
FB
SHDN
6
GND
2
VCC
Figure 4. 3rd-Order Butterworth LPF with MAX4090
Table 2. Bench Measurement Values
R1 = R2
(Ω)
C1
(p f)
L1
(µH)
RIS
(Ω)
3dB
BW
(MHz)
75
330
1.8
0
8.7
20
150
150
3.9
50
9.0
20
200
120
4.7
50
9.3
22
300
82
8.2
100
8.7
20
Table 3. 3rd-Order Butterworth Lowpass
Filter Normalized Values
ATTENUATION
AT 27MHz
(dB)
Rn1 = Rn2
(Ω)
Cn1 (F)
Cn2 (F)
Cn3 (F)
Ln1 (H)
1
0.923
0.923
0.06
1.846
Table 4. Bench Measurement Values
R1 = R2 (Ω)
C1 (pF)
C2 (pF)
C3 (pF)
L (µH)
RIS (Ω)
3dB BW (MHz)
ATTENUATION AT
27MHz (dB)
75
220
220
15.0
2.2
0
9.3
43
150
120
120
6.8
4.7
50
8.9
50
300
56
56
3.3
10.0
100
9.0
45
Sag Correction
In a 5V application, the MAX4090 can use the sag configuration if an AC-coupled output video signal is
required. Sag correction refers to the low-frequency
compensation for the highpass filter formed by the
150Ω load and the output capacitor. In video applications, the cutoff frequency must be low enough to pass
the vertical sync interval to avoid field tilt. This cutoff
frequency should be less than 5Hz, and the coupling
capacitor must be very large in normal configuration,
typically > 220µF. In sag configuration, the MAX4090
eliminates the need for large coupling capacitors, and
instead requires two 22µF capacitors (Figure 6) to
reach the same performance as the large capacitor.
Bench experiments show that increasing the output
coupling capacitor C5 beyond 47µF does not improve
the performance. If the supply voltage is less than 4.5V,
the sag correction is not recommended for the
MAX4090.
_______________________________________________________________________________________
9
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
Layout and Power-Supply Bypassing
FREQUENCY RESPONSE
The MAX4090 operates from single 2.7V to 5.5V supply. Bypass the supply with a 0.1µF capacitor as close
to the pin as possible. Maxim recommends using
microstrip and stripline techniques to obtain full bandwidth. To ensure that the PC board does not degrade
the device’s performance, design it for a frequency
greater than 1GHz. Pay careful attention to inputs and
outputs to avoid large parasitic capacitance. Whether
or not you use a constant-impedance board, observe
the following design guidelines:
• Do not use wire-wrap boards; they are too inductive.
• Do not use IC sockets; they increase parasitic
capacitance and inductance.
0
-10
GAIN (dB)
-20
-30
-40
-50
-60
0.1
1
10
100
FREQUENCY (MHz)
• Use surface-mount instead of through-hole components for better, high-frequency performance.
• Use a PC board with at least two layers; it should be
as free from voids as possible.
Figure 5. Frequency Response for R1 = R2 = 150Ω
• Keep signal lines as short and as straight as possible.
Do not make 90° turns; round all corners.
VCC
3-POLE RECONSTRUCTION LPF
C3
6.8pF
C7
1µF
4
L1
4.7µH
VIDEO
CURRENT
DAC
R1
150Ω
C1
120pF
C2
120pF
RIS
49.9Ω
C4
0.1µF
VCC
3
IN
R2
150Ω
OUT
1
C6
22µF
MAX4090
5
FB
SHDN
C5
22µF
6
GND
2
VCC
Figure 6. Sag Correction Configuration
10
______________________________________________________________________________________
R3
75Ω
VOUT
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
MAX4090
VCC = 2.7V TO 5.5V
VCC
CBYP
0.1µF
ESIGNAL
SHDN
MAX4090
CIN
0.1µF
RSOURCE
75Ω
IN
OUT
RIN
75Ω
ROUT
75Ω
EOUT
RL
75Ω
CLAMP
FB
GND
Figure 7. Typical Operating Circuit
Chip Information
TRANSISTOR COUNT: 755
PROCESS: BiCMOS
______________________________________________________________________________________
11
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX4090
3V/5V, 6dB Video Buffer with Sync-Tip Clamp
and 150nA Shutdown Current
PACKAGE OUTLINE, SOT-23, 6L
21-0058
F
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2004 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.