ML2009 Просмотр технического описания (PDF) - Micro Linear Corporation
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ML2009 Datasheet PDF : 11 Pages
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desired gain setting. The relationship between the register
0 and 1 bits and the corresponding analog gain values is
shown in Tables 1 and 2. Note that C3-C0 select the
coarse gain, F3-F0 select the fine gain, and ATTEN/GAIN
selects either gain or attenuation.
1.3 Output Buffer
The final analog stage is the output buffer. This amplifier
has internal gain of 1 and is designed to drive 600Ω,
100pF loads. Thus, it is suitable for driving a telephone
hybrid circuit directly without any external amplifier.
Table 1. Fine Gain Settings (C3 – C0 = 0)
Ideal Gain (dB)
F3 F2 F1 F0 ATTEN/GAIN = 1 ATTEN/GAIN = 0
0000
0.0
0.0
0001
–0.1
0.1
0010
–0.2
0.2
0011
–0.3
0.3
0100
–0.4
0.4
0101
–0.5
0.5
0110
–0.6
0.6
0111
–0.7
0.7
1000
–0.8
0.8
1001
–0.9
0.9
1010
–1.0
1.0
1011
–1.1
1.1
1100
–1.2
1.2
1101
–1.3
1.3
1110
–1.4
1.4
1111
–1.5
1.5
2.0 DIGITAL INTERFACE
The architecture of the digital section is shown in the
preceding black diagram.
The structure of the data registers or latches is shown in
Figures 10 and 11 for the ML2008 and ML2009,
respectively. The registers control the attenuation/gain
setting bits and with the ML2008 the power down bit.
Tables 1 and 2 describe how the data word programs the
gain.
The difference between the ML2008 and ML2009 is in the
register structure. The ML2008 is an 8-bit data bus
version. This device has one 8-bit register and one 2-bit
register to store the 9 gain setting bits and 1 powerdown
bit. Two write operations are necessary to program the full
10 data bits from eight external data pins. The address pin
A0 controls which register is being written into. The
powerdown bit, PDN, causes the device to be placed in
powerdown. When PDN = 1, the device is powered
ML2008, ML2009
1.4 Power Supplies
The digital section is powered between VCC and GND,
or 5V. The analog section is powered between VCC and
VSS and uses AGND as the reference point, or ±5V.
GND and AGND are totally isolated inside the device to
minimize coupling from the digital section into the analog
section. Typically this is less than 100µV. However, AGND
and GND should be tied together physically near the
device and ideally close to the common power supply
ground connection.
Typically, the power supply rejection of VCC and VSS
to the analog output is greater than –60dB at 1KHz. If
decoupling of the power supplies is still necessary in a
system, VCC and VSS should be decoupled with respect
to AGND.
Table 2. Coarse Gain Settings (F3 – F0 = 0)
Ideal Gain (dB)
C3 C2 C1 C0 ATTEN/GAIN = 1 ATTEN/GAIN = 0
0000
0.0
0.0
0001
–1.5
1.5
0010
–3.0
3.0
0011
–4.5
4.5
0100
–6.0
6.0
0101
–7.5
7.5
0110
–9.0
9.0
0111
–10.5
10.5
1000
–12.0
12.0
1001
–13.5
13.5
1010
–15.0
15.0
1011
–16.5
16.5
1100
–18.0
18.0
1101
–19.5
19.5
1110
–21.0
21.0
1111
–22.5
22.5
down. In this state, the power consumption is reduced by
removing power from the analog section and forcing the
analog output, VOUT, to a high impedance state. While the
device is in powerdown, the digital section is still
functional and the current data word remains stored in the
registers. When PDN = 0, device is in normal operation.
The ML2009 is a 9-bit data bus version. This device has
one 9-bit register to store the 9 gain setting bits. The full 9
data bits can be programmed with one write operation
from nine external data pins.
The internal registers or latches are edge triggered. The
data is transferred from the external pins to the register
output on the rising edge of WR. The address pin, A0,
controls which register the data will be written into as
shown in Figures 1 and 2. The CS control signal selects
the device by allowing the WR signal to latch in the data
only when CS is low. When CS is high, WR is inhibited
from latching in new data into the registers.
7
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