Tripath Technology, Inc. – Preliminary Technical Information
.
In a bridged system, stated in terms of the components described in the feedback section, the values for Ra
and Rb are determined as follows (Rd = 0.176 x Ra):
⎛
⎞
0.952× R3
R2 || 25K
Ra = Rb×⎜
− 0.048⎟
⎜
⎟
⎝
⎠
where R2||25k is the parallel combination of R2 and 25k Ohms. In a single ended (half bridge) system, the
component value relationships would be, stated in terms of the components in the feedback section:
⎛
⎞
1.90× R3
R1|| R2 || 25K
Ra = Rb×⎜
+ 0.90⎟
⎜
⎟
⎝
⎠
where Rd = 0.176 x Ra, and R1||R2||25k is the parallel combination of R1, R2, and 25k Ohms.
When the entire system is using single ended output stages or the entire system is using bridged output
stages, the unused VCLAMP pin should be grounded.
OVER- AND UNDER-VOLTAGE PROTECTION
The TCD6001 senses the power rails through external resistor networks connected to VNNSENSE and
VPPSENSE. The over- and under-voltage limits are determined by the values of the resistors in the
networks. If the supply voltage falls outside the upper and lower limits determined by the resistor networks,
the TCD6001 shuts off the output stages of the amplifiers. The removal of the over-voltage or under-voltage
condition returns the TCD6001 to normal operation. Please note that trip points specified in the Electrical
Characteristics table are at 25°C and may change over temperature.
The TCD6001 has built-in over and under voltage protection for both the VPP and VNN supply rails. The
nominal operating voltage will typically be chosen as the supply “center point.” This allows the supply
voltage to fluctuate, both above and below, the nominal supply voltage.
VPPSENSE performs the over and undervoltage sensing for the positive supply, VPP. VNNSENSE
performs the same function for the negative rail, VNN. When the current through RVPPSENSE (or RVNNSENSE
goes below or above the values shown in the Electrical Characteristics section (caused by changing the
power supply voltage), the power stage will be muted. VPPSENSE is internally biased at 2.5V and
VNNSENSE is biased at 1.25V.
)
Once the supply comes back into the supply voltage operating range (as defined by the supply sense
resistors), the power stage will automatically be unmuted and will begin to amplify. There is a hysteresis
range on both the VPPSENSE and VNNSENSE pins. If the amplifier is powered up in the hysteresis band
the power stage will be muted. Thus, the usable supply range is the difference between the over-voltage
turn-off and under-voltage turn-off for both the VPP and VNN supplies. It should be noted that there is a
timer of approximately 200mS with respect to the over and under voltage sensing circuit. Thus, the supply
voltage must be outside of the user defined supply range for greater than 200mS for the power stage to be
muted.
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TCD6001 – JL/Rev. 0.9/07.05
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
