SGM89000 Datasheet, PDF (10/14 Pages) SG Micro Corp – Capless 2Vrms Line Driver

SGM89000
APPLICATION INFORMATION (continued)
Supply
Capless 2Vrms Line Driver
with Adjustable Gain
Supply Ramp
SD
Time for AC coupling
capacitors to charge
Figure 5. Power-Up Sequence
External Under-Voltage Detection
External under-voltage detection can be used to mute/shut down the SGM89000 before an input device can
generate a pop.
The threshold seen at the UVP pin is 1.13V. A hysteresis is introduced with a resistive divider, where thresholds for
startup and shutdown are determined respectively as follows:
Startup Threshold: V_UDPR = 1.13V × (R11 + R12) / R12
Shutdown Threshold: V_UDPF = 1.13V × (R11+R12) / R12 - 4.8μA × (R13 + R11 || R12) × (R11 + R12) / R12
Hysteresis: 4.8μA × (R13 + R11 || R12) × (R11 + R12) / R12
The R13 is optional. If the R13 is not used, the UVP pin connects to the divider center tap directly.
VSUP_MO
R11
R13
UVP pin 11
R12
Capacitive Load
The SGM89000 has the ability to drive large capacitive load up to 220pF directly, and larger capacitive loads can be
accepted by adding a series resistor of 47Ω or larger.
Gain-Setting Resistors
The gain setting resistors, R_IN and R_FB, must be placed close to the input pins to minimize the capacitive loading on
these pins and to ensure maximum stability of the SGM89000.
SG Micro Corp
www.sg-micro.com
FEBRUARY 2017
10