tk2070 Tripath Technology Inc., tk2070 Datasheet - Page 17

• Manufacturer Part Number: tk2070
• Description: Stereo 70w 4ohm Class-t Digital Audio Amplifier Driver Using Digital Power Processing Dpp Technology
• Manufacturer: Tripath Technology Inc.

Using the resistor values from above, the actual minimum over voltage turn off points will be:
The other three trip points can be calculated using the same formula but inserting the appropriate
I
minimum overvoltage turn off and maximum under voltage turn-off for the VPP supply.
P r o t e c t i o n C i r c u i t s
The TK2070 is protected against over-current, over / under-voltage and over-temperature conditions.
Output overcurrent conditions are detected on the TPS1035.
Figure 2 shows an overcurrent detection circuit that will mute the amplifier whenever the TPS1035
detects an overcurrent condition. The fault pin (pin 8 of the TPS1035) is a overcurrent indicator that
is high (approximately 5.4V) during normal operation and low (0V) if an overcurrent condition is
detected. The fault pin will go low and turn on the PNP transistor and pull the Mute pin to 5V if the
switch is closed. In this circuit, whenever the switch is open the Mute pin will be at 5V and the
amplifier will be muted.
O v e r - t e m p e r a t u r e P r o t e c t i o n
An over-temperature fault occurs if the junction temperature of the part exceeds approximately
165qC. The thermal hysteresis of the part is approximately 30qC, therefore the fault will automatically
clear when the junction temperature drops below 135qC.
H M U T E
The HMUTE pin on the TC2001 is a 5V logic output that indicates various fault conditions within the
device. These conditions include: over-current, overvoltage and undervoltage. The HMUTE output is
high whenever a fault condition occurs and is capable of directly driving an LED through a series 2k:
resistor.
17
VPPSENSE
TPS1035
TPS1035
VPP
VPP
current value. As stated earlier, the usable supply range is the difference between the
MIN_OV_TUR
RANGE
8
8
VPP
FAULT
FAULT
N_OFF
MIN_OV_TUR
FD LL914
FD LL914
R
VPP1
1K
1K
N_OFF
u
:
:
I
VPPSENSE
-
Figure 2
VPP
(MIN_OV_TU
10K
MAX_UV_TUR
:
5V
RN_OFF)
2N 3906
20K
T r i p a t h T e c h n o l o g y , I n c . - T e c h n i c a l I n f o r m a t i o n
N_OFF
:
5V
TK2070 – MC/2.1/10-03
510K
(Pin 24 of TC2001)
:
MUTE Pin