THS6032 Datasheet, PDF (21/31 Pages) Texas Instruments – LOW-POWER ADSL CENTRAL-OFFICE LINE DRIVER

THS6032
LOW-POWER ADSL CENTRAL-OFFICE LINE DRIVER
SLOS233C – APRIL1999 – REVISED MARCH 2000
APPLICATION INFORMATION
shutdown function (continued)
+VCC(H)
IBIAS–S1
IBIAS–1
Active
Load
QS1
DGND
QS2
QS3
Q1
1 kΩ
+IN
Pin
To Internal
Output
QS4
Node
Q2
Q3
Q5
–IN
Pin
Q6
Q4
To Output
Drive
Circuitry
IBIAS–S2
IBIAS–2
Active
Load
Shut–Down Circuitry
–V _CC(H)
Figure 44. Simplified THS6032 Input Stages
Because the DGND pin voltage is effectively at a noninverting terminal, any signal or voltage fluctuation at this
node is amplified by the THS6032. This could possibly cause a noisy output to appear during shutdown
operation. Figure 45 shows the frequency response of the THS6032 due to an input signal at the DGND
terminal. The maximum DGND voltage signal which the THS6032 will follow linearly during shutdown operation
is less than ± 4 V. With this dynamic range capability, it is recommended that the DGND pin be as noise-free
as possible to ensure proper transmission line termination.
DGND OUTPUT AMPLITUDE
vs
FREQUENCY
3
2
VO(PP) = 0.2 V
1
0
–1
–2
VO(PP) = 2 V
–3
VCC(H) = ± 15 V
–4
VCC(L) = ± 5 V
RL = 25 Ω
–5 VSD = +10 V
VI = DGND Pin
–6
100 k
1M
10 M
f – Frequency – Hz
Figure 45
100 M
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