PHILIPS TDA8785

INTEGRATED CIRCUITS
DATA SHEET
TDA8785
8-bit high-speed analog-to-digital
converter with gain and offset
controls
Product specification
Supersedes data of 1996 Jan 17
File under Integrated Circuits, IC02
1997 Dec 18
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
• Gain, slow offset control inputs and DAC output swing
of 1.5 V (p-p) range (2.75 ±0.75 V)
FEATURES
• 8-bit analog-to-digital converter (ADC)
• 2.75 V reference voltage
• 8-bit digital-to-analog converter (DAC)
• Internal references for ADC and DAC.
• Sampling rate up to 30 Msps for both ADC and DAC
• Binary or two’s complement 3-state TTL outputs
APPLICATIONS
• TTL compatible inputs and outputs
• 100 MHz variable gain amplifier (0 to 20 dB) externally
controlled
• CCD type of systems
• All analog inputs and outputs are differential (can also
be used in single-ended format)
• Copier
• Scanner
• Video acquisition.
• Analog input signal from 0.1 to 1.0 V (p-p) differential
• Offset amplifier with:
GENERAL DESCRIPTION
– Slow offset control (±250 mV)
The TDA8785 is an 8-bit analog-to-digital converter with
gain and offset controls for the input signal. An internal
8-bit DAC provides fast offsets control.
– Fast offset control (±500 mV) eventually driven by
internal DAC.
• ADC output code of 8 (typ.) when analog input signal
and offset correction inputs are 0 V
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
VCCA1
analog supply voltage 1
4.75
5.0
5.25
V
VCCA2
analog supply voltage 2
4.75
5.0
5.25
V
VCCD
digital supply voltage
4.75
5.0
5.25
V
VCCO
TTL output supply voltage
4.75
5.0
5.25
V
ICCA
analog supply current
−
80
−
mA
ICCD
digital supply current
−
30
−
mA
ICCO
TTL output supply current
−
9
−
mA
INL
integral non-linearity
0 to 20 dB gain; ramp input
−
±0.7
±1.8
LSB
DNL
differential non-linearity
0 to 20 dB gain; ramp input
−
±0.2
±0.7
LSB
fclk(max)
maximum clock frequency
ADC and DAC
30
−
−
MHz
B
controlled gain amplifier
bandwidth
−
100
−
MHz
Ptot
total power dissipation
−
600
−
mW
ORDERING INFORMATION
TYPE
NUMBER
PACKAGE
NAME
DESCRIPTION
VERSION
TDA8785H QFP44 plastic quad flat package; 44 leads (lead length 1.3 mm); body 10 × 10 × 1.75 mm SOT307-2
1997 Dec 18
2
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
BLOCK DIAGRAM
handbook, full pagewidth
VCCA1
VCCA2
1
AGND1
2
3
VRB Vref
B
AGND2
4
6
7
DEC2
OF
DEC1
36
5
35
34
REGULATORS
Vi(p)
Vi(n)
VSOFF(p)
VSOFF(n)
VFOFF(p)
VFOFF(n)
VFSAD(p)
VFSAD(n)
43
44
37
38
42
41
OFFSET
AMPLIFIER
GAIN
ADC
8
TTL
OUTPUTS
26 to 33
39
40
VCCA
150 Ω
VDACO(p)
VDACO(n)
9
8
VFSDAC(p)
10
VFSDAC(n)
11
25
150 Ω
24
TDA8785
VCCO
OGND
DAC
CLOCK
DRIVER
8 12 to 19
DA7 to DA0
CLOCK
DRIVER
20
22
CLKDAC
CLKADC
Fig.1 Block diagram.
1997 Dec 18
AD0 to AD7
8
3
23
21
VCCD DGND
MBG681
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
PINNING
SYMBOL
PIN
DESCRIPTION
SYMBOL
PIN
DESCRIPTION
VCCA1
1
analog supply voltage 1 (+5 V)
OGND
24
output ground
VCCA2
2
analog supply voltage 2 (+5 V)
VCCO
25
output supply voltage (+5 V)
AGND1
3
analog ground 1
AD0
26
output data; bit 0 (LSB)
AGND2
4
analog ground 2
AD1
27
output data; bit 1
DEC2
5
decoupling input 2
AD2
28
output data; bit 2
B
6
bandwidth adjustment node input
AD3
29
output data; bit 3
VRB
7
ADC reference voltage output
bottom (decoupling)
AD4
30
output data; bit 4
AD5
31
output data; bit 5
VDACO(n)
8
DAC negative voltage output
AD6
32
output data; bit 6
VDACO(p)
9
DAC positive voltage output
AD7
33
output data; bit 7 (MSB)
VFSDAC(p)
10
DAC full-scale positive control
voltage input
OF
34
output format input
DEC1
35
decoupling input 1
Vref
36
reference voltage output (2.75 V)
VSOFF(p)
37
slow offset amplifier positive
voltage input
VSOFF(n)
38
slow offset amplifier negative
voltage input
VFSDAC(n)
11
DAC full-scale negative control
voltage input
DA7
12
DAC TTL input; bit 7 (MSB)
DA6
13
DAC TTL input; bit 6
DA5
14
DAC TTL input; bit 5
DA4
15
DAC TTL input; bit 4
VFSAD(p)
39
gain control positive voltage input
DA3
16
DAC TTL input; bit 3
VFSAD(n)
40
gain control negative voltage input
DA2
17
DAC TTL input; bit 2
VFOFF(n)
41
DA1
18
DAC TTL input; bit 1
fast offset amplifier negative
voltage input
DA0
19
DAC TTL input; bit 0 (LSB)
VFOFF(p)
42
CLKDAC
20
DAC clock input
fast offset amplifier positive voltage
input
DGND
21
digital ground
Vi(p)
43
analog positive voltage input
Vi(n)
44
analog negative voltage input
CLKADC
22
ADC clock input
VCCD
23
digital supply voltage (+5 V)
1997 Dec 18
4
Philips Semiconductors
Product specification
34 OF
VCCA1
1
33 AD7
VCCA2
2
32 AD6
AGND1
3
31 AD5
AGND2
4
30 AD4
DEC2
5
29 AD3
TDA8785
26 AD0
VDACO(p)
9
25 VCCO
VFSDAC(p) 10
24 OGND
VFSDAC(n) 11
23 VCCD
5
CLKADC 22
DGND 21
CLKDAC 20
28 AD2
DA0 19
DA1 18
8
DA2 17
VDACO(n)
DA3 16
27 AD1
DA4 15
7
DA5 14
VRB
DA6 13
6
DA7 12
B
Fig.2 Pin configuration.
1997 Dec 18
35 DEC1
TDA8785
36 Vref
37 VSOFF(p)
38 VSOFF(n)
39 VFSAD(p)
40 VFSAD(n)
41 VFOFF(n)
43 Vi(p)
44 Vi(n)
handbook, full pagewidth
42 VFOFF(p)
8-bit high-speed analog-to-digital converter
with gain and offset controls
MBG680
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
The internal 8-bit DAC operates at the ADC clock rate to
allow dynamic corrections on the input signal chain based
on the signal processing information carried out after the
digital conversion. The output voltage amplitude of the
DAC can be controlled via a different input voltage (which
can also be single) in a range of ±25% with a 150 Ω DAC
output load.
FUNCTIONAL DESCRIPTION
The TDA8785 is composed of an 8-bit ADC (30 Msps),
a wide-band gain amplifier, an input offset amplifier and an
8-bit dynamic adjustment DAC.
Input signal
Two input pins are provided to apply a differential input
signal with a wide range (100 to 1000 mV differential).
It is also possible to apply a single signal by setting a DC
voltage on one of the differential pins and supplying the
signal to the other.
The DAC can also be used for the gain or the slow offset
control with some external DC voltage adaptations and
can be considered as a separate function of the ADC
chain. The DAC can be used independently, for example
as a video DAC.
Controlled gain amplifier
8-bit ADC
The gain amplifier is used to adjust the wide input signal
range to the fixed ADC input range of 1 V (p-p).
The 8-bit ADC converts a signal of 1 V (p-p) from the
controlled gain amplifier into an 8-bit coded digital word at
a maximum rate of 30 Msps. Its reference voltage is
supplied by the general voltage regulator. The output data
format can either be binary, two’s complement or 3-state
by selecting pin OF.
A large gain of 20 dB can be achieved with low-noise
behaviour and a large bandwidth of 100 MHz to correctly
amplify square type signals with step edges. Using pin 6,
it is possible to reduce the internal bandwidth of the gain
amplifier via an external capacitor and thus improve its
noise behaviour. The gain amplifier is controlled via an
external differential voltage (single input can also be
applied).
When all the differential inputs on the offset amplifier
(VSOFF(p), VSOFF(n), VFOFF(n), VFOFF(p), Vi(p) and Vi(n)) are at
0 V (equivalent to both inputs short-circuited), the output
code of the ADC is code 8.
Input offset amplifier and adjustment DAC
Internal voltage regulator
The Input offset amplifier contains two different control
inputs (which can also be single):
An internal voltage regulator provides all the references for
the different blocks. A stable 2.75 V voltage reference
output is provided for use in the application environment.
One application is to connect all the slow control inputs
(VFSDAC(p), VFSDAC(n), VSOFF(p), VSOFF(n), VFSAD(p) and
VFSAD(n)) to this reference, either to their two differential
inputs to get the nominal settings or to one of the
differential inputs to have easy single-input control.
• Slow offset control, for slow variation characteristics
(e.g. temperature, supply voltage, etc.)
• Fast offset control, for correction related to the clock
rate.
Slow offset control is carried out by an external voltage
while fast offset control is digitally carried out via the
internal 8-bit DAC with external connections of the
respective pins VDACO(n), VDACO(p), VFOFF(n) and VFOFF(p).
1997 Dec 18
All these control inputs have the same control range.
6
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
VCCA
analog supply voltage
−0.3
+7.0
V
VCCD
digital supply voltage
−0.3
+7.0
V
VCCO
output supply voltage
−0.3
+7.0
V
∆VCC
supply voltage difference between
VCCA and VCCD
−1.0
+1.0
V
VCCD and VCCO
−1.0
+1.0
V
−1.0
+1.0
V
referenced to AGND −0.3
+7.0
V
VCCD
V
VCCA and VCCO
Vi
input voltage
Vclk(p-p)
clock input voltage for switching (peak-to-peak value) referenced to DGND −
Io
output current
−
6
mA
Tstg
storage temperature
−55
+150
°C
Tamb
operating ambient temperature
0
70
°C
Tj
junction temperature
−
150
°C
THERMAL CHARACTERISTICS
SYMBOL
Rth j-a
1997 Dec 18
PARAMETER
CONDITIONS
thermal resistance from junction to ambient
in free air
7
VALUE
UNIT
75
K/W
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
CHARACTERISTICS
VCCA1 = VCCA2 = VCCD = VCCO = 4.75 to 5.25 V; AGND, DGND and OGND short-circuited together;
VCCA to VCCD = VCCD to VCCO = VCCA to VCCO = −0.25 to +0.25 V; Tamb = 0 to 70 °C;
typical values measured at VCCA = VCCD = VCCO = 5 V and Tamb = 25 °C; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX. UNIT
Supplies
VCCA1
analog supply voltage 1
4.75
5.0
5.25
V
VCCA2
analog supply voltage 2
4.75
5.0
5.25
V
VCCD
digital supply voltage
4.75
5.0
5.25
V
VCCO
TTL output supply voltage
4.75
5.0
5.25
V
ICCA
analog supply current
−
80
−
mA
ICCD
digital supply current
−
37
−
mA
ICCO
TTL output supply current
−
9
−
mA
Reference voltages (pins Vref and VRB)
Vo(ref)
output reference voltage
Vline
line regulation voltage
Io(L)
2.60
2.75
2.90
V
−
4
−
mV
output load current
−0.5
−
+0.5
mA
VRB
reference voltage output bottom
(decoupling)
−
VCCA − 2.5
−
V
Voffset(B)
offset voltage bottom
code 0 − VRB
−
250
−
mV
∆VADC
ADC reference voltage difference
between
code 0 and 255
−
1
−
V
VCCA = 4.75 to 5.25 V
Analog inputs (pins Vi(p) and Vi(n)); see Table 1
Vi(diff)(p-p)
differential input voltage Vi(p) − Vi(n)
(peak-to-peak value)
0 dB gain
−
1000
−
mV
20 dB gain
−
100
−
mV
VI
DC input voltage
2.5
3.0
3.5
V
Ii
input current
−
7
−
µA
Zi
input impedance
−
20
−
kΩ
Ci
input capacitance
−
1
−
pF
Fast offset amplifier inputs (pins VFOFF(p) and VFOFF(n)); DC parameters
VFOFF(p)
positive input voltage
0 dB gain
−
500
−
mV
20 dB gain
−
50
−
mV
0 dB gain
−
500
−
mV
20 dB gain
−
50
−
mV
VFOFF(n)
negative input voltage
VI
DC input voltage
VCCA − 0.75 VCCA − 0.25 VCCA
V
Ii
input current
−
4
−
µA
Zi
input impedance
−
20
−
kΩ
Ci
input capacitance
−
1
−
pF
1997 Dec 18
8
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
SYMBOL
PARAMETER
TDA8785
CONDITIONS
MIN.
TYP.
MAX. UNIT
Slow offset amplifier inputs (pins VSOFF(p) and VSOFF(n)) gain amplifier at 0 dB; note 1
Voffset(ADC) offset voltage at ADC input
Ii
VSOFF(p) = 2 V;
VSOFF(n) = 2.75 V
−
−0.25
−
V
VSOFF(p) = 2.75 V;
VSOFF(n) = 2.75 V
−
0
−
V
VSOFF(p) = 3.5 V;
VSOFF(n) = 2.75 V
−
0.25
−
V
−
10
−
µA
−
8
−
code
−15
0
+15
code
input current
Offset reference code; Tamb = 25 °C
OFSRE
offset reference (ADC output code)
OFSER
offset reference error on code 8
Vi(p) = Vi(n);
VFOFF(p) = VFOFF(n);
VSOFF(p) = VSOFF(n);
amplifier gain set at
0 dB
Gain control inputs (pins VFSAD(p) and VFSAD(n)); see Fig.7
Gv(min)
minimum voltage gain
VFSAD(p) = 2 V;
VFSAD(n) = 2.75 V
−
−
0
dB
Gv(max)
maximum voltage gain
VFSAD(p) = 3.5 V;
VFSAD(n) = 2.75 V
20
−
−
dB
Ii
input current
−
10
−
µA
DAC full-scale control inputs (pins VFSDAC(p) and VFSDAC(n)) 150 Ω output load on pins VDACO(p) and VDACO(n);
see Table 3
VDACO(n)
Ii
DAC negative output voltage (pin 8)
VCCA
−
V
code 255 at DAC inputs; −
VFSDAC(p) = 2 V;
VFSDAC(n) = 2.75 V
VCCA − 0.4
−
V
code 255 at DAC inputs; −
VFSDAC(p) = 2.75 V;
VFSDAC(n) = 2.75 V
VCCA − 0.5
−
V
code 255 at DAC inputs; −
VFSDAC(p) = 3.5 V;
VFSDAC(n) = 2.75 V
VCCA − 0.6
−
V
−
1
−
µA
−
500
−
Ω
−
150
−
Ω
code 0 at DAC inputs
input current
−
Bandwidth adjustment node input (pin B); see Fig.6
Zi
input impedance
8-bit DAC; fclk = 30 MHz, ramp input; Tamb = 25 °C
Zo
output impedance
INL
integral non-linearity
−
±0.4
±0.8
LSB
DNL
differential non-linearity
−
±0.4
±1.0
LSB
1997 Dec 18
9
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
SYMBOL
PARAMETER
TDA8785
CONDITIONS
MIN.
TYP.
MAX. UNIT
Digital inputs (pins CLKDAC, CLKADC and DA7 to DA0)
VIL
LOW-level input voltage
0
−
0.8
VIH
HIGH-level input voltage
2.0
−
VCCD V
IIL
LOW-level input current
VIL = 0.4 V
−400
−
−
µA
V
IIH
HIGH-level input current
VIH = 2.7 V
−
−
100
µA
Zi
input impedance
fclk = 10 MHz
−
4
−
kΩ
Ci
input capacitance
fclk = 10 MHz
−
4.5
−
pF
V
ADC output format (pin OF); see Table 2
VIL
LOW-level input voltage
0
−
0.2
VIH
HIGH-level input voltage
2.6
−
VCCD V
Vi(Z)
input voltage in high impedance
state
−
1.20
−
V
IIL
LOW-level input current
VIL = 0.4 V
−370
−130
−
µA
IIH
HIGH-level input current
Vclk = 2.7 V
−
300
450
µA
V
ADC digital outputs
VOL
LOW-level output voltage
IOL = 2 mA
0
−
0.6
VOH
HIGH-level output voltage
IOH = −0.4 mA
2.4
−
VCCO V
note 2
30
−
−
MHz
ADC and DAC switching; see Fig.4
fclk(max)
maximum clock frequency
tCPH
clock pulse width HIGH
12
−
−
ns
tCPL
clock pulse width LOW
12
−
−
ns
−
±0.7
±1.8
LSB
±0.2
±0.7
LSB
47
−
dB
Analog processing; note 3
INL
integral non-linearity
ramp input (full-scale);
0 to 20 dB gain
DNL
differential non-linearity
ramp input (full-scale);
0 to 20 dB gain
S/N
signal-to-noise ratio
(without harmonics)
fi = 2 MHz
B
1997 Dec 18
bandwidth
0 dB gain
−
10 dB gain
−
45
−
dB
20 dB gain
−
43
−
dB
−
100
−
MHz
−3 dB
10
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
SYMBOL
PARAMETER
TDA8785
CONDITIONS
MIN.
TYP.
MAX. UNIT
Timing
ADC DIGITAL OUTPUTS (CL = 15 pF)
tds
sampling delay time
−
1.5
−
ns
th
output hold time
7
−
−
ns
td
output delay time
−
−
16
ns
DAC OUTPUTS (PINS VDACO(p) AND VDACO(n))
tSU; DAT
data set-up time
note 4
−0.3
−
−
ns
tHD; DAT
data hold time
note 4
−
−
2
ns
tS
DAC setting time (10 to 90%)
RL = 150 Ω; CL = 15 pF
−
8
−
ns
RSA
residual setting accuracy
note 5; see Fig.8
0.1
2.5
%
3-STATE OUTPUT DELAY TIMES (see Fig.5)
tdZH
enable HIGH
−
15
20
ns
tdZL
enable LOW
−
15
20
ns
tdHZ
disable HIGH
−
13
20
ns
tdLZ
disable LOW
−
10
20
ns
Notes
1. Vos is proportional to the amplifier gain. For instance, Vos at 20 dB is the one indicated at 0 dB multiplied by 10.
2. It is recommended that the rise and fall times of the clock are >1 ns. In addition a good layout for the digital and
analog grounds is recommended.
3. Analog processing from signal inputs or fast offset amplifier inputs to ADC digital output; fclk = 30 MHz; no external
filtering on pin 6 (B).
4. The data set-up time (tSU; DAT) is the minimum period preceding the rising edge of the clock, that the input data must
be stable in order to be correctly registered. A negative set-up time indicates that the data may be initiated after the
rising edge and still be recognized. The data set hold time (tHD; DAT) is the minimum period following the rising edge
of the clock, that the input data must be stable in order to be correctly registered. A negative hold time indicates that
the data may be released prior to the rising edge and still be recognized.
5. The residual settling accuracy is defined as follows. When a full-scale step is applied to the DAC, the initial settling
shows a fast settling behaviour. For the final part, the DAC analog output shows a slow settling behaviour.
The Residual Settling Accuracy (RSA) is defined as the full-scale error at the cross-over point at time tX.
1997 Dec 18
11
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
Table 1
TDA8785
Output coding and input voltage (typical values; referenced to AGND, Vi(p) − Vi(n) = 1 V (p-p), 0 dB gain, no
offset correction
Vi(p) − Vi(n)
STEP
BINARY OUTPUT BITS
TWO’S COMPLEMENT OUTPUT BITS
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
Underflo
w
→0.032
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
−0.032
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
−
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
.
−
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
8
0
0
0
0
0
1
0
0
0
1
0
0
0
1
0
0
0
.
−
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
254
−
1
1
1
1
1
1
1
0
0
1
1
1
1
1
1
0
255
0.968
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
Overflow
>0.968
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
Table 2
OF input coding
OF
AD0 to AD7
0
active, two’s complement
1
high impedance
open circuit; note 1
active, binary
Note
1. Use C ≥ 10 pF to DGND.
Table 3
Input coding and DAC output voltages (typical values; referenced to VCCA regardless of the offset voltage);
VFSDAC(p) = VFSDAC(n)
BINARY INPUT DATA
DAC OUTPUT VOLTAGES (V)
CODE
DA7
DA6
DA5
DA4
DA3
DA2
DA1
DA0
ZL = 10 kΩ
ZL = 150 Ω
VDACO(p)
VDACO(n)
VDACO(p)
VDACO(n)
0
0
0
0
0
0
0
0
0
−1.0
0
−0.5
0
1
0
0
0
0
0
0
0
1
−
−
−
−
.
.
.
.
.
.
.
.
.
.
.
.
.
128
1
0
0
0
0
0
0
0
−0.5
−0.5
−0.25
−0.25
.
.
.
.
.
.
.
.
.
.
.
.
.
254
1
1
1
1
1
1
1
0
−
−
−
−
255
1
1
1
1
1
1
1
1
0
−1.0
0
−0.5
1997 Dec 18
12
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
t SU; DAT
handbook, full pagewidth
TDA8785
t HD; DAT
3.0 V
input data
stable
1.4 V
0V
3.0 V
1.4 V
CLKDAC
0V
MBG682
The shaded areas indicate when the input data may change and be correctly registered. Data input update must be completed within 0.3 ns, after the
first rising edge of the clock (tSU; DAT is negative; −0.3 ns). Data must be held at least 2 ns after the rising edge (tHD; DAT = +2 ns).
Fig.3 Data set-up and hold times (DAC).
t CPL
handbook, full pagewidth
t CPH
1.4 V
CLKADC
sample N
sample N + 1
sample N + 2
Vi(p) − Vi(n)
t ds
th
2.4 V
DATA
AD0 to AD7
DATA
N-2
DATA
N-1
DATA
N
DATA
N+1
1.4 V
0.4 V
td
Fig.4 Timing diagram.
1997 Dec 18
13
MBG683
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
V CCD
handbook, full pagewidth
50 %
OF
1.15 V
t dHZ
t dZH
HIGH
90 %
output
data
50 %
HIGH Z
t dLZ
t dZL
HIGH Z
output
data
50 %
LOW
10 %
V CCD
3.3 kΩ
S1
TDA8785
15 pF
TEST
S1
t dLZ
t dZL
VCCD
VCCD
t dHZ
GND
t dZH
GND
OF
MBG684
fOF = 100 kHz.
Fig.5 Timing diagram and test conditions of 3-state output delay time.
MBG691
102
handbook, halfpage
(1)
f−3 dB
handbook, halfpage
Gv
(dB)
S/N
(dB)
(MHz)
MBG692
25
48
20
46
10
15
(2)
10
1
44
5
10−1
10−1
1
10
102
CB (pF)
42
103
0
−0.75
−0.50
−0.25
0
0.50
0.75
0.25
VFSAD(p) − VFSAD(n) (V)
(1) f−3 dB.
(2) Signal-to-noise ratio.
The controlled gain amplifier is set at 20 dB gain.
Fig.6
Gain amplifier bandwidth and acquisition
chain S/N ratio as a function of the external
capacitance on pin 6.
1997 Dec 18
Fig.7
14
Typical amplifier gain (Gv) as a function of
the differential input voltage;
VFSAD(p) − VFSAD(n).
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
MBK516
handbook, full pagewidth
VDACO
RSA
(%)
100
90
10
0
ts
t
tx
Fig.8 DAC time response when a full-scale step is applied.
INTERNAL PIN CONFIGURATIONS
handbook, halfpage
ook, halfpage
VCCO
VCCA
VFSDAC(p), VSOFF(p),
VFSAD(p), VFOFF(p), Vi(p)
or
VFSDAC(n), VSOFF(n),
VFSAD(n), VFOFF(n), Vi(n)
AD0 to AD7
AGND
DGND
MBG686
MBG685
Fig.10 Analog inputs.
Fig.9 TTL data outputs.
1997 Dec 18
15
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
andbook, halfpage
dbook, halfpage
VCCA
VCCA
500 Ω
RLAD
B
VRB
AGND
AGND
MBG688
MBG687
Fig.11 Bandwidth input (B).
Fig.12 VRB.
ndbook, halfpage
VCCD
handbook, halfpage
40 kΩ
DA7 to DA0
or
CLKDAC
or
CLKADC
200 Ω
150
Ω
150
Ω
VDACO(p)
VDACO(n)
MBG690
DGND
MBG689
Fig.13 DAC inputs.
1997 Dec 18
Fig.14 DAC outputs.
16
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
APPLICATION INFORMATION
handbook, full pagewidth
B
AGND1
VCCA1
AGND2
VCCA2
1
VCCA1
2 pF
2
3
4
6
Vref
DEC2 DEC1 OF
3.3
nF
VRB
100
nF
7
36
10
pF
100
nF
5
35
1
nF
34
REGULATORS
Vi(p)
Vi(n)
VSOFF(p)
VSOFF(n)
VFOFF(p)
VFOFF(n)
VFSAD(p)
VFSAD(n)
VCCA
150
Ω
150
Ω
VDACO(p)
43
44
37
38
OFFSET
AMPLIFIER
GAIN
ADC
AD0
to
AD7
42
41
39
40
VCCA
150 Ω
25
150 Ω
24
9
8
VDACO(n)
VFSDAC(p)
10
VFSDAC(n)
11
TDA8785
VCCO
OGND
DAC
CLOCK
DRIVER
8 12 to 19
DA7 to DA0
CLOCK
DRIVER
20
22
CLKDAC
CLKADC
Fig.15 Application diagram.
1997 Dec 18
26 to 33
TTL
OUTPUTS 8
8
17
23
21
VCCD DGND
MBG693
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
PACKAGE OUTLINE
QFP44: plastic quad flat package; 44 leads (lead length 1.3 mm); body 10 x 10 x 1.75 mm
SOT307-2
c
y
X
A
33
23
34
22
ZE
e
E HE
A A2
wM
(A 3)
A1
θ
bp
Lp
pin 1 index
L
12
44
1
detail X
11
wM
bp
e
ZD
v M A
D
B
HD
v M B
0
2.5
5 mm
scale
DIMENSIONS (mm are the original dimensions)
UNIT
A
max.
A1
A2
A3
bp
c
D (1)
E (1)
e
HD
HE
L
Lp
v
w
y
mm
2.10
0.25
0.05
1.85
1.65
0.25
0.40
0.20
0.25
0.14
10.1
9.9
10.1
9.9
0.8
12.9
12.3
12.9
12.3
1.3
0.95
0.55
0.15
0.15
0.1
Z D (1) Z E (1)
1.2
0.8
1.2
0.8
θ
o
10
0o
Note
1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
OUTLINE
VERSION
REFERENCES
IEC
JEDEC
EIAJ
ISSUE DATE
95-02-04
97-08-01
SOT307-2
1997 Dec 18
EUROPEAN
PROJECTION
18
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
If wave soldering cannot be avoided, for QFP
packages with a pitch (e) larger than 0.5 mm, the
following conditions must be observed:
SOLDERING
Introduction
•A double-wave (a turbulent wave with high upward
pressure followed by a smooth laminar wave)
soldering technique should be used.
There is no soldering method that is ideal for all IC
packages. Wave soldering is often preferred when
through-hole and surface mounted components are mixed
on one printed-circuit board. However, wave soldering is
not always suitable for surface mounted ICs, or for
printed-circuits with high population densities. In these
situations reflow soldering is often used.
•The footprint must be at an angle of 45° to the board
direction and must incorporate solder thieves
downstream and at the side corners.
During placement and before soldering, the package must
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the
adhesive is cured.
This text gives a very brief insight to a complex technology.
A more in-depth account of soldering ICs can be found in
our “IC Package Databook” (order code 9398 652 90011).
Reflow soldering
Maximum permissible solder temperature is 260 °C, and
maximum duration of package immersion in solder is
10 seconds, if cooled to less than 150 °C within
6 seconds. Typical dwell time is 4 seconds at 250 °C.
Reflow soldering techniques are suitable for all QFP
packages.
The choice of heating method may be influenced by larger
plastic QFP packages (44 leads, or more). If infrared or
vapour phase heating is used and the large packages are
not absolutely dry (less than 0.1% moisture content by
weight), vaporization of the small amount of moisture in
them can cause cracking of the plastic body. For more
information, refer to the Drypack chapter in our “Quality
Reference Handbook” (order code 9397 750 00192).
A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.
Repairing soldered joints
Fix the component by first soldering two diagonallyopposite end leads. Use only a low voltage soldering iron
(less than 24 V) applied to the flat part of the lead. Contact
time must be limited to 10 seconds at up to 300 °C. When
using a dedicated tool, all other leads can be soldered in
one operation within 2 to 5 seconds between
270 and 320 °C.
Reflow soldering requires solder paste (a suspension of
fine solder particles, flux and binding agent) to be applied
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.
Several methods exist for reflowing; for example,
infrared/convection heating in a conveyor type oven.
Throughput times (preheating, soldering and cooling) vary
between 50 and 300 seconds depending on heating
method. Typical reflow peak temperatures range from
215 to 250 °C.
Wave soldering
Wave soldering is not recommended for QFP packages.
This is because of the likelihood of solder bridging due to
closely-spaced leads and the possibility of incomplete
solder penetration in multi-lead devices.
CAUTION
Wave soldering is NOT applicable for all QFP
packages with a pitch (e) equal or less than 0.5 mm.
1997 Dec 18
TDA8785
19
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
TDA8785
DEFINITIONS
Data sheet status
Objective specification
This data sheet contains target or goal specifications for product development.
Preliminary specification
This data sheet contains preliminary data; supplementary data may be published later.
Product specification
This data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
1997 Dec 18
20
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
NOTES
1997 Dec 18
21
TDA8785
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
NOTES
1997 Dec 18
22
TDA8785
Philips Semiconductors
Product specification
8-bit high-speed analog-to-digital converter
with gain and offset controls
NOTES
1997 Dec 18
23
TDA8785
Philips Semiconductors – a worldwide company
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Tel. +9-5 800 234 7381
Middle East: see Italy
Netherlands: Postbus 90050, 5600 PB EINDHOVEN, Bldg. VB,
Tel. +31 40 27 82785, Fax. +31 40 27 88399
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Tel. +64 9 849 4160, Fax. +64 9 849 7811
Norway: Box 1, Manglerud 0612, OSLO,
Tel. +47 22 74 8000, Fax. +47 22 74 8341
Philippines: Philips Semiconductors Philippines Inc.,
106 Valero St. Salcedo Village, P.O. Box 2108 MCC, MAKATI,
Metro MANILA, Tel. +63 2 816 6380, Fax. +63 2 817 3474
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Slovenia: see Italy
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2092 JOHANNESBURG, P.O. Box 7430 Johannesburg 2000,
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Tel. +46 8 632 2000, Fax. +46 8 632 2745
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Tel. +41 1 488 2686, Fax. +41 1 481 7730
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TAIPEI, Taiwan Tel. +886 2 2134 2865, Fax. +886 2 2134 2874
Thailand: PHILIPS ELECTRONICS (THAILAND) Ltd.,
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Ukraine: PHILIPS UKRAINE, 4 Patrice Lumumba str., Building B, Floor 7,
252042 KIEV, Tel. +380 44 264 2776, Fax. +380 44 268 0461
United Kingdom: Philips Semiconductors Ltd., 276 Bath Road, Hayes,
MIDDLESEX UB3 5BX, Tel. +44 181 730 5000, Fax. +44 181 754 8421
United States: 811 East Arques Avenue, SUNNYVALE, CA 94088-3409,
Tel. +1 800 234 7381
Uruguay: see South America
Vietnam: see Singapore
Yugoslavia: PHILIPS, Trg N. Pasica 5/v, 11000 BEOGRAD,
Tel. +381 11 625 344, Fax.+381 11 635 777
For all other countries apply to: Philips Semiconductors,
International Marketing & Sales Communications, Building BE-p,
P.O. Box 218, 5600 MD EINDHOVEN, The Netherlands, Fax. +31 40 27 24825
Internet: http://www.semiconductors.philips.com
© Philips Electronics N.V. 1997
SCA56
All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner.
The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed
without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license
under patent- or other industrial or intellectual property rights.
Printed in The Netherlands
547047/1200/02/pp24
Date of release: 1997 Dec 18
Document order number:
9397 750 03005