Datasheet CVA6629S Datasheet (Calogic LLC)

CORPORATION

Triple 180MHz

CRT Driver

CVA6629S

FEATURES

•• Rise/Fall Ti me. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5ns

•• Swing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70V

P-P

•• Symmetrical Rise and Fall Time

•• Excellent Gray Scale Linearity

APPLICATION

•• CRT Driver for up to 110kHz Monito rs with Resol utio n

upto 1600 x 1280 (Non-Interlaced).

CONNECTION DIAGRAM AND SIM PLIFI ED SCHEM ATIC

DESCRIPTION

The CVA6629S contains three wideband amplifiers designed
specifically to drive high resolution CRTs . It features excellent
gray scale linearity and high load capacitance driving
capability. This device can drive monitors with resolution of
1600 x 1280 (non-interlac ed) with pixel freque ncy of 350 MHz.

The part is housed in 12L Ceramic package with heat sink
grounded.

ORDERING INFORMATION
Part Package Temperature

o

CVA6629S CY12B -20

Q1

C to +100oC

Q2

5.7K

1

3

1

2

4

5

6

7

8

9

IN R

V+ R

GND R

IN G

V+ G

OUT R

OUT G

GND G

V+ B

12

11

10

IN B

OUT B

GND B

250

Q3

Q4

1j-40

CAL OGIC CORPORA TION, 237 Whitney Place, Fremont, California 94539, Telephone: [phone], FAX: [phone]

CVA6629S

ABSOLUTE MAXIMUM RATINGS

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85V

Storage Tempera tu re. . . . . . . . . . . . . . . . . . -25

o

C to +125oC

CORPORATION

Operating Temperature . . . . . . . . . . . . . . . . -20

o

C to +100oC

Lead Temperat ure . . . . . . . . . . . . . . . . . . . . . . . . . . . +300

o

C

DC ELECTRICAL CHARACTERISTICS VS = 80V, CL = 10pF, T

SYMBOL CHARACTERISTICS MIN TYP MAX UNITS

I

CC

V

IN DC

V

OUT DC

A

V

Supply Current 37 42 mA
Input DC Level 1.3 1.5 1.7 V
Output DC Level 36 40 44 V
Voltage Ga in 10 12 14 V
Gain Matching 0.2 dB

AC ELECTRICAL CHARACTERISTICS VS = 80V, CL = 10pF , V

SYMBOL CHARACTERISTICS MIN TYP MAX UNITS

t

r

t

f

BW Bandwidth 180 MHz
Le Linearity 5 %
OS Overshoot 4 %

Rise Time 2.8 3.5 ns
Fall Time 2.7 3.5 ns

= +25oC. See Figure 1.

CASE

OUT

= 50V

P-P

, T

CASE

= +25oC. See Figure 1.

FIGURE 1. TEST CIRCUIT

V

CC

C4 C6

L1

OUTPUT

C

L

INPUT

C1

C2

R1

R2

C3

2,6,10

V

R4

1/3
CVA6629S

IN

1,5,9
V

CC

4,8,12

V

OUT

D1

R5 R6

D2

3,7,11

GND

R1 = 15
R2 = 430

Ω

Ω

R4 = 200k

Ω

R5 = 22
R6 = 22

Ω

C1 = VARIABLE 20 TO 150pF
TYPICAL 68pF
C2 = VARIABLE 4 to 20pF
TYPICAL 17pF
C3 = 75pF

C4 = 10µf/160V

µ

C6 = 0.01
C = 10pF

L

f/160V

D1 = DS464
D2 = DS464
L1 = 150nH

1Q-03

CA LOGIC CORPORA TION, 237 Whit ney Place , Fremo nt , California 9453 9, Telephone: [phone], FAX: [phone]

CORPORATION

APPLICATION INFORMATION

CVA6629S

The CVA6629S is a transimpedance amplifier with two stage
feedback configurations. Any change in input current will be
reflected as change in output voltage swing. A resistor in
series with the input will change the CVA6629S into a voltage
amplifier. The output is emitter follower with load(capacitive)
driven capability.

With a true Class AB output stage, the rise and fall time is
symmetric.

CVA6627S has an internal feedback resistor of 5.7KΩ. In the
absence of any input signal, the V

R

V

OUT

(DC) = (1 +

F

) VIN (DC); RB = 250Ω.

R

B

DC is set by

OUT

An input resist or RG will set the gain as

R

F

= (

V

OUT

) VIN ; RG = gain resistor.

R

G

Input and Transfer Cha racteristics

An input current swing of ±5. 2mA causes the output to c hang e
by ±25V. A resistor of 390Ω will set the gain to -11. Input pins
are internal DC feedback nodes and thus have low
impedance. These pins must be fed fro m a series RC net wor k
for high frequenc y empha sis.

The following section will explain how to overcome some of
the problems that are typical.

1) Input drive: CVA6629S gives best results when the
amplifier is driven by a fast pulse with proper voltage level.
Since all pre-amplifiers have output from 0 to 8V, a level
shifter is required. Using CVA4402, buffer plus level shifter,
this can be easily real ized.

2) Smear: For a box pattern with white background, a shadow
after the black is cal led smear. It is due to the tilt of the white
level. It can easily be adjusted by adding an RC feedback
network (R4, C3). The value of R4 will affect the gain, for
CV A6629 S, the typical value is 200K.

3) Streaks and overshoot: For a cross-hatch pattern with
white background, a whitish line will appear just after the
black line, this is called s treak. Looking at the waveform it is
due to undershoot of the waveform. For a Box pattern with
white background, a dark black area just after white is a sign
of overshoot. It is due to overshoot of the wavef or m. Adju stin g
the value of C2, R1, C1 will get the optimum result. The value
of C2 should be kept at minimum for less overshoot, typical is
<20pF. Value of R1 should be less than 47 ohms otherwise
rise and fall time will suffer. First adjust the overshoot to
minimum, keeping value of C1 and R2 to minimum, then
adjust the undershoot (Streak) by adjusting C3 again. Since
both need to be adjusted together, this may need a few
iteration to get to the opt im um r esult .

It should be n oted here that the output peaking with L1 and
R3 is only to overcome the affect of stray capacitance. Keep
the value of L1 to minimum, typ 150nH and R, to be 820Ω.
The value of L1 depends on the associated capacitance with
the board and the cable(if any). CVA6629S is specifically
designed to handle extra capacitance associated with the
cable(typ. 10pF) assuming the driver is not part of the neck
board. The value of R3 should be less than 1K to damped the
resonant ring in g.

The output of CVA6629S is not short circuit proof. Precaution
is required.

Thermal Characteristics

Under normal operating conditions the CVA6629S will
dissipate up to 8W. The maximum allowed case temperature
is +100

o

C. To calculate maximum heatsink thermal resistance

use the following equation:

(100 − 50°)

Rth =

18W

= 2.8°C/W

The Thermalloy #11699 is one example of a heatsink that
meets this requir emen t.

CAL OGIC CORPORA TION, 237 Whit ney Plac e, Fre m ont, California 945 39, Telephone: [phone], FAX: [phone]

CVA6629S

1Q-07

P-P

BOX PATTERN — 50V

10ns/DIV

10V/DIV

1Q-08

CROSS HATCH PATTERN

— WHITE BACKGROUND

5ns/DIV

10V/DIV

D2

R1

C2

C1

R3

L1

CRT

R4

C3

2,6,10

1,5,9

4,8,12

PRE
AMP

CVA6629S

D3

3,7,11

1Q-04

R1 = 15

Ω

R2 = 390

Ω

R3 = 820

Ω

R4 = 200K
R5 = 39

Ω

C1 = VARIABLE 20 TO 150pF
TYPICAL 68pF
C2 = VARIABLE 4 to 20pF
TYPICAL 17pF

D1 = DS464
D2 = DS464
L1 = 150nH

C3 = 75pF
C4 = 1

µ

F

R2

C4

R5

CVA

4402

+12V

-5V

CVA
4502

DAC

R1

FIGURE 2. APLICATION CIRCUI T

CORPORATION

ELECTRICAL CHARACTERISTICS

BOX PATTERN — 50V

10V/DIV

10ns/DIV

P-P

1Q-05

CROSS HATCH PATTERN
— BLACK BACKGROUND

10V/DIV

5ns/DIV

1Q-06

CAL OGIC CORPORA TION, 237 Whit ney Plac e, Fre m ont, California 945 39, Telephone: [phone], FAX: [phone]

CORPORATION

ELECTRICAL CHARACT ERISTICS (continued)

CVA6629S

V - DEVICE INPUT (VOLTS)

V (VOLTS)

IN

OUT

2.5

1.5

0.5

V (DEVICE INPUT) vs. V

OUTIN

2

1

0

5.2

5.6

104

15.3

20.3

25.2

30.4

35.6

40.8

46.1

51.4

56.5

62.3

67.4

V (VOLTS)

OUT

V vs. V

90

OUT IN

72.47678.1

78.6

78.8

1Q-09

79

80
70
60
50
40
30
20
10

0

-5

-4

-3

-2

-1

-0

-4.5

-3.5

-2.5

-1.5

V (VOLTS)

0.511.522.533.544.555.5

-0.5

IN

1Q-10

I vs. V

15

OUTIN

10

5

0

IN (ma)

-5

-10

-15

5.2

5.6

104

15.3

20.3

25.2

30.4

35.6

40.8

46.1

51.4

56.5

V (VOLTS)

OUT

Inform at ion furni shed by Calogic is believed to be accurate and reliable. Howe ver, no responsibility is assum ed for its use: nor for any in fring eme nt of pate nts or other
rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent rights of Calogic.

62.3

76

67.4

72.4

78.1

79

78.6

78.8

1Q-11

CA LOGIC CORPORA TION, 237 Whit ney Place , Fremo nt , California 9453 9, Telephone: [phone], FAX: [phone]

CORPORATION

PACKAGE DIM ENSIO NS

CVA6627S

CVA6627S

CORPORATION

CORPORATION

APPLICATION INFORMATION

The CVA6627S is an transimpedance amplifier with two stage
feedback configurations. Any change in input current will be
reflected as change in output voltage swing. A resistor in
series with the input will change the CV A6627 S in to a volta g e
amplifier. The output is emitter follwer with load(capacitive)
driven capability. (see schematic).

Both intput and output stage has separate by pass capacitor.
Emitter capacitor is included to improve the dynamic
performance for large voltage swing. With true Class AB
output stage, the rise and fa ll time is sym m et ric.

CVA6627S has an internal feedback resistor of 5.7KΩ. In the
absencs of any input signal, the vout DC is set by

R

(DC) = (1 +

V

out

F

) Vin (DC); RB = 250Ω

R

b

An input resist or RG will set the gain as

R

F

= (

V

out

) Vin ; Rg = gain resistor

R

g

CVA6627S

value of L to minimum, typ 150 150nH and R to be 820Ω. The
value of L depends on the associated capacitance with the
board and the cable(if any). CVA6627S is specifically
designed to handle extra capacitance associated with the
cable(typ. 10pF) assuming the driver is not part of the neck
board. The value of R should be less than 1K to damped the
resonant ring in g.

The output of CVA6627S is not short circuit proof. Precaution
is requried.

Input and Transfer ch ara ct eri st ic s

An input current swing of ±4, 4ma causes the output to
change by ±25V. A resistor of 430 will set the gain to -13.
Input pins are internal dc feedback nodes and thus have low
impedance. These pins must be fed fro m a series RC net wor k
for high frequenc y empha sis.

Following section will explain how to overcome some of the
problems that are typical.

1) Input drive: CVA6627 gives best results when the amplifer
is driven by a fast pulse with proper voltage level. Since all
pre-amplieriers have output from 0 to 8V, a level shifter is
requried, also most pre-amplifiers cannot drive large
capacitive load to drive a buffer is requried. A simple t ransist or
like 25C4693 and a zener with -5V supply can do the job with
little affect on the r esp onse .

2) Smear: On the monitor for a box pattern with white
background a shado after the black is called smear. It is due
to tilt of the white level. It can easily be adjusted by adding R C
feedback network (R1, C1). The value of R1 will affect the
gain, for CVA6627S the typical value is 200K. The value of C1
will be adjusted t o get opt im um ringin g.

3) Streks and overshoot: For a cross-hatch pattern with white
backgorund, a whitish line will appear just after the black line,
this is called streak. Looking at the wave form it is due to
undershoot of the waveform. For a Box pattern with white
background a dark black area just after white is a sign of
overshoot. It is due to overshoot of the waveform. Adusting
the value of C2, R2, C3 will get the optimum result. The value
of C2 should be kept at minimum for less overshoot, typical is
<20pF. V alue of R2 shold be less than 47 ohms other wise rise
and fall time will suffer. First adjust the overhoot to minimum,
keeping value of C2 and R2 minimum, then adjust the
undershoot(Streak) by adusuting C3 again. Since both need
to be adjusted together, this may need few iteration to get to
the optimum result .

It should be noted here that the output peaking with L and R3
is only to overcome the affect of stray capacitance. Keep the

CVA6629S

CORPORATION

CORPORATION

Inform at ion furni shed by Calogic is believed to be accurate and reliable. Howe ver, no responsibility is assum ed for its use: nor for any in fring eme nt of pate nts or other
rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent rights of Calogic.

CAL OGIC CORPORA TION, 237 W hitn ey Place, Fremont, Californ ia 94539, Telephone: [phone], FAX: [phone]