TK2019 Tripath, TK2019 Datasheet - Page 17

• Manufacturer Part Number: TK2019
• Description: STEREO 20W (4OHM) CLASS-T DIGITAL AUDIO AMPLIFIER
• Manufacturer: Tripath

P r o t e c t i o n C i r c u i t s
The TK2019 is protected against over-current, over / under-voltage and over-temperature conditions.
Figure 3 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 an overcurrent indicator and
is normally high (approximately 5.4V). When an overcurrent condition is detected this pin will go low
(0V). When the fault pin goes low Q2 will turn on and pull the Mute pin of the TC2001 to 5V (if the
switch is closed). This is due to the fact that the emitter voltage of Q2 is controlled by the HMUTE pin
of the TC2001 through Q1. If HMUTE is low the emitter voltage of Q2 will be connected to the 5V line.
If HMUTE is high Q2 is disabled and the mute pin will be pulled low through the 20kΩ resistor. In this
circuit, whenever the switch is open the Mute pin will be pulled up to 5V and the amplifier will be
muted.
Whenever the MUTE pin on the TC2001 is high (or enabled) the HMUTE pin will also switch high.
The sleep pin of the TPS1035 is controlled by HMUTE of the TC2001 so that during any mute or
overcurrent condition the TPS1035 is placed in sleep mode.
FAULT pin is low and mutes the TC2001. Q1 controls the emitter voltage of Q2 through HMUTE so
that whenever the SLEEP is enabled the TC2001 can become unmuted again.
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 TPS1035 exceeds approximately
165°C. The thermal hysteresis of the part is approximately 30°C, therefore the fault will automatically
clear when the junction temperature drops below 135°C.
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 or mute is enabled.
driving an LED through a series 2kΩ resistor.
17
(Pin 8 of TC2001)
HMUTE Pin
SLEEP
SLEEP
3
3
TPS1035
TPS1035
8
8
FAULT
FAULT
(Pin 8 of TC2001)
FDLL914
FDLL914
HMUTE Pin
Figure 3
1K
1K
5V
Ω
Ω
30K
Ω
3K
Ω
Q1
2N3906
10K
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
Ω
+
The HMUTE pin is capable of directly
22uF
Whenever SLEEP is enabled, the
Q2
2N3906
20K
Ω
TK2019 – MC/2.1/10-03
5V
510K
(Pin 24 of TC2001)
Ω
MUTE Pin