tk2070 Tripath Technology Inc., tk2070 Datasheet - Page 16

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

Wound iron powder toroidal cores are the recommended inductor choice for the TK2070. Toroidal
cores have less flux leakage compared to shielded bobbin or shielded SMD inductors, resulting in
reduced EMI and improved channel separation.
Micrometals Type-2 iron powder (Carbonyl-E) core. This core material has low permeability metal
powder and a distributed air gap for increased energy storage capability. This allows for a small
footprint with high peak current capability.
M i n i m u m a n d M a x i m u m S u p p l y V o l t a g e O p e r a t i n g R a n g e
The TK2070 can operate over a wide range of power supply voltages from +7.5V to +25V. In order to
optimize operation for either the low or high range, the user must select the proper values for R
and R
Over- and Under-Voltage Protection
The TC2001 senses the power rails through external resistor networks connected to VPPSENSE.
The over- and under-voltage limits are determined by the values of the resistors in the networks, as
described in the table “Test/Application Circuit Component Values”. If the supply voltage falls outside
the upper and lower limits determined by the resistor networks, the TC2001 shuts off the TPS1035
output stage. The removal of the over-voltage or under-voltage condition returns the TK2070 to
normal operation. Please note that trip points specified in the Electrical Characteristics table are at
25qC and may change over temperature.
The TC2001 has built-in over and under voltage protection the VDD supply rail.
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. For the TK2070 only the VDD supply
rail will be sensed and the VNN sensing will not be used so pin 17 of the TC2001 will be shorted to
ground.
VPPSENSE (pin 19) performs the over and undervoltage sensing for the positive supply, VDD. When
the current through R
section (caused by changing the power supply voltage), the TK2070 will be muted. VPPSENSE (pin
19) is internally biased at 2.5V.
Once the supply comes back into the supply voltage operating range (as defined by the supply sense
resistors), the TK2070 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 TK2070 will be muted. Thus, the usable supply range is the difference between the over-
voltage turn-off and under-voltage turn-off for the VDD supply. 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 TK2070 to
be muted.
The equation for calculating R
R
the actual VCC trip voltage without considering the effect of R
16
VPP2
FBC
compensates for the internal bias point. Thus, R
Set
I
VPPSENSE.
.
R
VPPSENSE
VPP1
R
VPP2
I
VPPSENSE
can be any of the currents shown in the Electrical Characteristics table for
VPP
R
VPPSENSE
VPP1
.
VPP1
goes below or above the values shown in the Electrical Characteristics
is as follows:
For typical applications we recommend the
VPP1
can be used for the direct calculation of
VPP2
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
.
TK2070 – MC/2.1/10-03
The nominal
FBB
,