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Tripath Technology, Inc. - Technical Information
TPS4100A FOUR CHANNEL BRIDGED OUTPUT POWER STAGE
Technical Information Revision 1.1 - November 2005
GENERAL DESCRIPTION
The TPS4100A is a 4 channel bridged (16 power transistors) output power stage. The TPS4100A accepts 5V CMOS logic signals from a Class-T processor, such as TCD6001, to create a high fidelity 4-channel audio amplifier. The TPS4100A has been designed specifically for automotive head unit applications operating on a single 10-26V supply.
APPLICATIONS
FEATURES
Automotive Head Units and Trunk Amplifiers DVD Receivers Multimedia Speaker Systems
BENEFITS
4-channel output stage - with integrated driver and FETs - in a single 32-pin SSIP package Low external component count Single-supply operation
Four H-Bridge outputs High Efficiency High Power @25.0V 100Wsat. sq. wave @ 4 High Efficiency 88% @ 100W 4 AM "Low EMI" mode with connection to appropriate Class-T controller Mates seamlessly with TCD6001 Digital Input Class-T controller Mute and Stand-By function Protection Modes: Output Short to VPP and Ground Output Short across Load Load Dump Protection Over-/Under-Voltage Protection Over-current Protection Over-temperature Protection Fortuitous Open Ground
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Tripath Technology, Inc. - Technical Information
Absolute Maximum Ratings (Note 1)
SYMBOL VPP VPPMAX VPPAM VINRANGE TSTORE IR Tj PD ESD ESD Supply Voltage (VPP) Peak Supply Voltage (t<50ms) Supply Voltage in AM Mode (Note 2) Voltage Range for Input Section Pins (Note 3) Inputs (Pins 1-11) Storage Temperature Range Repetitive Peak Output Current Maximum Junction Temperature Total Power Dissipation (Tcase = 70C) ESD Susceptibility - Human Body Model (Note 4) ESD Susceptibility - Machine Model (Note 5) PARAMETER Value 33 60 18 -0.5 to 5.5 -55 to +150 14 150 80 2k 200 UNITS V V V V C A C W V V
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. See the table below for Operating Conditions. Note 2: Supply voltage is limited in AM Mode due to additional power dissipation of output stage when operating in Class B mode. Please note that the TPS4100A is still fully protected from load dump transients in AM Mode. Note 3: The input section pins (pins 1-9, 11,12) should not be connected to voltages over 5.5V with respect to pin 10 (AGND). Please note that pins 5, 11, and 12 are outputs and can be damaged if a voltage is forced externally. Note 4: Human body model, 100pF discharged through a 1.5K resistor. Note 5: Machine model, 220pF - 240pF discharged through all pins.
Operating Conditions (Note 6)
SYMBOL VPP VPPAM TA Supply Voltage (Note 6) Supply Voltage for AM Mode (Note 7) Operating Free Air Temperature Range PARAMETER MIN. 10 10 -40 TYP. 14.4 14.4 25 MAX. 26 16 85 UNITS V V C
Note 6: Recommended Operating Conditions indicate conditions for which the device is functional. See Electrical Characteristics for guaranteed specific performance limits. Note 7: Supply voltage is limited in AM Mode due to additional power dissipation of output stage when operating in Class B mode, as opposed to Switching Mode.
Thermal Characteristics
SYMBOL JC JA PARAMETER Junction-to-case Thermal Resistance Junction-to-ambient Thermal Resistance (still air) Value 1.0 20 UNITS
C/W C/W
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Tripath Technology, Inc. - Technical Information
Electrical Characteristics (Note 8)
TA = 25 C. Unless otherwise noted, the supply voltage is VPP=14.4V. See Application/Test Circuit.
SYMBOL ISTBY VIL VIH VIL VIH VIL VIH VOH VOL VIH VIL IAM PARAMETER Stand-By Current Stand-By On Threshold Voltage Stand-By Off Threshold Voltage Mute-On Threshold Voltage Mute-Off Threshold Voltage Yn/YnB Low Threshold Voltage Yn/YnB High Threshold Voltage Fault Reporting Logic Output High Voltage Open Drain Output Fault Reporting Logic Output Low Voltage AM Mode On Threshold Voltage AM Mode Off Threshold Voltage AM Mode Pin Input Current RFAULT = 51K AM pin High AM pin Low 2.7 1 1 2.7 3.5 1 Conditions VSLEEPB < 0.15V SLEEPB Low (amp off) SLEEPB High (amp on) MUTEB Low MUTEB High 2.7 0.6 2.3 1 MIN. TYP. 100 MAX. 200 0.5 UNITS A V V V V V V V V V V A
Note 8: Minimum and maximum limits are guaranteed but may not be 100% tested.
Performance Characteristics (Note 8)
TA = 25 C. Unless otherwise noted, RL = 4. Measurement Bandwidth = 20kHz. All specifications shown are applicable only when the TPS4100A is used in conjunction with the TCD6001 Class-T Controller. See Application/Test Circuit of TCD6001 data sheet for additional information.
SYMBOL POUT
PARAMETER Output Power (Continuous power/ channel)
CONDITIONS VPP=25V saturated sq. wave VPP=25V THD+N=10% VPP=25V THD+N=1% VPP=20V saturated sq. wave VPP=20V THD+N=10% VPP=20V THD+N=1% VPP=14.4V sat. sq. wave, RL = 2 VPP=14.4V THD+N=10%, RL = 2 VPP=14.4V THD+N=1%, RL = 2 VPP=14.4V saturated sq. wave VPP=14.4V THD+N=10% VPP=14.4V THD+N=1% VPP=25V, 4 x 100W sat sq wave
MIN. 95
TYP. 112 80 65 74 51 40 63 42 33 39 26 21 88
MAX.
UNITS W W W W W W W W W W W W %
Power Efficiency
AM Mode (Notes 8, 9)
TA = 25 C. Unless otherwise noted, the supply voltage is VPP=14.4V, RL = 4. Measurement Bandwidth = 20kHz. See Application/Test Circuit.
.
SYMBOL IOCD Pout PARAMETER Over-current detect Output Power (Note 7) VPP=16V, THD+N=10% VPP=14.4V, THD+N=10% CONDITIONS MIN. 5.5 20 16 TYP. MAX. UNITS A W W
Note 9: The TPS4100A heat sinking in AM Mode must be increased (as compared to Class-T mode) to sustain the typical output numbers. This is due to the lower efficiency of Class B output stage operation.
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Protection Circuits (Note 8)
TA = 25 C. Unless otherwise noted, the supply voltage is VPP=14.4V.
SYMBOL OVON OVOFF UVOFF UVON OTON OTOFF IOC VPMAX PARAMETER Over-voltage Threshold Over-voltage Reset Under-voltage Reset Under-voltage Threshold Over-Temperature Threshold Over-Temperature Reset Over-Current Detect Load Dump Voltage Withstand CONDITIONS Over-voltage turn on (amp muted) Over-voltage turn off (mute off) Under-voltage turn off (mute off) Under-voltage turn on (amp muted) Over-temperature turn on (amp muted) Over-temperature turn off (mute off) 1kHz single-shot ramp, VPP = 25V Test conditions, tr > 2.5ms, tpulse<50mS 7.8 150 120 10.5 60 MIN. 27.0 26.0 TYP. 30 28.0 9.5 8.1 160 130 12.5 10.0 8.6 170 140 MAX. 32.5 UNITS V V V V C C A V
TPS4100A Pinout
32-pin SSIP Package (Top view)
10 11 12 13 14 15
16 17
18 19
20 21 22 23 24
SLEEPB
Y1 Y1B Y2 Y2B Y3 Y3B Y4 Y4B MUTEB AM V5GEN AGND AGND CPUMP OUT4P
VPP4 PGND OUT4N OUT3N VPP3 OUT3P FAULT OUT2P VPP2 OUT2N OUT1N PGND VPP1 OUT1P DCAP
Note: The heat slug of the TPS4100A is connected to PGND.
4
PGND
25 26 27 28 29 30 31 32
1 2 3 4
5 6 7 8
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Tripath Technology, Inc. - Technical Information
TPS4100A Pinout
PIN
1 2, 4, 6, 8 3, 5, 7, 9 10
NAME/FUNCTION TYPE
SLEEPB Y1, Y2, Y3, Y4 Y1B, Y2B, Y3B, Y4B MUTEB
DESCRIPTION
INPUT (L) Logic input, ACTIVE LOW. Setting SLEEP to low puts the TPS4100A in sleep mode. Input range is 0 to 5V with 3.3V compliant inputs. INPUT (L) Non-inverted switching modulator inputs. INPUT (L) Inverted switching modulator inputs. INPUT (L) Logic Input, ACTIVE LOW. Setting MUTE to low puts the device in mute mode. Typically driven by external power supply or microcontroller. Input range is 0 to 5V with 3.3V compliant inputs. INPUT (L) Logic input, ACTIVE HIGH. Enables Analog Mode operation. Typically driven by Tripath controller. Input range is 0 to 5V with 3.3V compliant inputs. OUTPUT On chip 5V regulator bypass capacitor connection
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AM
12 12 13, 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
5VGEN HMUTEB AGND CPUMP OUT4P VPP4 PGND OUT4N OUT3N VPP3 OUT3P FAULT OUT2P VPP2 OUT2N OUT1N PGND VPP1 OUT1P DCAP PGND
OUTPUT (L) Logic output, ACTIVE LOW. HMUTEB low indicates TPS4100A is in mute mode GND Analog ground
OUTPUT Charge pump output capacitor OUTPUT Positive Output Channel 4 POWER GND OUTPUT OUTPUT POWER OUTPUT Positive Supply Voltage Channel 4 Power Ground for Outputs 3 and 4 Negative Output Channel 4 Negative Output Channel 3 Positive Supply Voltage Channel 3 Positive Output Channel 3
OUTPUT (L) Open Drain Logic Output, ACTIVE HIGH. FAULT high indicates fault condition. OUTPUT POWER OUTPUT OUTPUT GND POWER OUTPUT GND Positive Output Channel 2 Positive Supply Voltage Channel 2 Negative Output Channel 2 Negative Output Channel 1 Power Ground for Outputs 1 and 2 Positive Supply Voltage Channel 1 Positive Output Channel 1 Power Ground
OUTPUT Oscillator output for driving external charge pump circuit
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Tripath Technology, Inc. - Technical Information
TPS4100A Connection Diagram
TPS4100A
SLEEPB
CPUMP
MUTEB
OUT4N
OUT3N
OUT2N
OUT1N
V5GEN
OUT4P
OUT3P
OUT2P
OUT1P
DCAP2 31
FAULT
PGND
PGND
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
VPP Cbr 0.1uF VPP Cs 0.1uF Ccp 0.1uF close to PIN18 Ccp 3.3uF VPP VPP VPP Cbr 0.1uF close to PIN18 VPP VPP Do Do Do Do Cbr 0.1uF Cbr 390uF close to PIN28 VPP VPP
VPP VPP Ccp 0.1uF CPUMP Cbr 0.1uF Dcp close to PIN28 Ccp 0.1uF VPP Dcp
SLEEPB Y1 Y1B Y2 Y2B Y3 Y3B Y4 Y4B HMUTEB AM_MODE FAULT FB1N FB1P Cs 3.3uF
Do Do
Do Do
Do Do
Do Do
Do Do
Do Do
Lo 10uH Co 0.47uF Co 0.47uF Rz 10;2W Cz 0.22uF
32
1
2
3
4
5
6
7
8
9
PGND
GNDA
GNDA
VPP4
VPP3
VPP2
VPP1
Y1B
Y2B
Y3B
Y4B
AM
Y1
Y2
Y3
Y4
RL
Lo 10uH FB2N FB2P Co 0.47uF Co 0.47uF Rz 10;2W Cz 0.22uF
RL
Lo 10uH FB3N FB3P Co 0.47uF Co 0.47uF Rz 10;2W Cz 0.22uF
RL
Lo 10uH FB4N FB4P Co 0.47uF Co 0.47uF Rz 10;2W Cz 0.22uF
RL
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Tripath Technology, Inc. - Technical Information
External Components Description (Refer to the Connection Diagram)
Components CS CBR Description Supply decoupling for the power supply pins. For optimum performance, these components should be located close to the TPS4100A and returned to their respective "ground" as shown in the Application/Test Circuit. Supply decoupling for the high current full-bridge supply pins. These components must be located as close to the power supply pins as possible to minimize output ringing which causes power supply overshoot. By reducing overshoot, these capacitors maximize the TPS4100A reliability. These capacitors should have good high frequency performance including low ESR and low ESL. Supply decoupling for the charge pump (high side gate drive supply) circuitry. These components must be located as close to the TPS4100A as possible. Output diode, which is used to minimize output overshoots/undershoots on the output nodes These devices clamp the output to the low impedance node formed by the close connection of CBR. Note the connection shown in the Application/Test Circuit. The "high side" diode protects the bottom side device from excessive BVDSS due to overshoots on the output node. The "bottom side" diode protects the top side device from excessive BVDSS due to undershoots on the output node. This device must be an ultra fast rectifier capable of sustaining the entire supply range and high peak currents. Zobel capacitor, which in conjunction with RZ, terminates the output filter at high frequencies. Use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. Zobel resistor, which in conjunction with CZ, terminates the output filter at high frequencies. The combination of RZ and CZ minimizes peaking of the output filter under both no load conditions or with real world loads, including loudspeakers, which usually exhibit a rising impedance with increasing frequency. Depending on the program material, the power rating of RZ may need to be adjusted. If the system requires full power operation at 20kHz then the power rating for RZ will likely need to be increased. Output inductor, which in conjunction with CO and CDO, demodulates (filters) the switching waveform into an audio signal. Forms a second order filter with a cutoff frequency of f C = 1 ( 2 L O C TOT ) and a quality factor of
CCP DO
CZ RZ
LO
Q = R L C TOT
CO RFAULT DCP
2 L O C TOT where CTOT = CO.
Output capacitor, which, in conjunction with LO, demodulates (filters) the switching waveform into an audio signal. Use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. Pull-up resistor for the open drain FAULT pin output. Recommended resistor value is 51k. Charge pump diodes. Used to generate floating supply for driving high side circuitry. Small signal diodes such as 1N4148 are recommended for these components.
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Tripath Technology, Inc. - Technical Information
Typical Performance
THD+N versus O utput Power
100 50 20 10 5 RL = 4 2 % 1 0.5 RL = 2 V PP = 14.4V f = 1Khz BW = 22Hz - 20kHz(AES17)
THD+N versus Output Power
100 RL = 4 50 f = 1Khz 20 BW = 22Hz - 20kHz(AES17) 10 5 2 1 0.5 % 0.2 0.1 0.05 0.02 VPP = 25V VPP = 20V
0.2 0.1 0.05 0.02 0.01 1 2 5 10 W 20 50 100
0.01 1
2
5
10 W
20
50
100
200
THD+N versus O utput Power
100 50 20 10 5 2 % 1 0.5 0.2 0.1 0.05 0.02 0.01 1 2 5 10 W 20 50 100 V PP = 25V V PP = 14.4V V PP = 20V RL = 8 f = 1Khz BW = 22Hz - 20kHz(AES17)
Output Power versus Supply Voltage
120 110 100 90
RL = 4 f= 1 kH z BW= 22H z - 20kH z(AES17)
TH D +N = SSW
Output P ower (W )
TH D +N = 10%
80 70 60 50 40 30 20 10 0 10 12 14 16 18 20 22 24 26
TH D +N = 1%
Supply V oltage (V PP)
E fficiency and Power D issipation versus Total output Power
90 80 70 E fficienc y 45 40 35 30
E fficiency and Power D issipation versus Total output Power
90 80 70 E fficienc y 90 80 70 60 50 40 30 Power Dissipation
VPP = 25V RL = 4 f= 1kH z BW = 22H z - 20kH z(AES17)
E ff (%)
60 50 40 30 20 10 0 0 50 100 150 P ower Dissipation
VPP = 20V RL = 4 f= 1kH z BW = 22H z - 20kH z(AES17)
P diss (W)
E ff (%)
60 50 40 30 20 10 0 0 50 100 150 200 250 300 350 400 450
25 20 15 10 5 0 300
20 10 0 500
200
250
Total Output P ower (W )
Total Output Power (W )
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P diss (W )
Tripath Technology, Inc. - Technical Information
Typical Performance AM Mode
THD+N versus Output Power
100 50 20 10 5 AM MO DE RL = 4 f = 1Khz BW = 22Hz - 20kHz(AES17)
E fficiency and P ower D issipation versus Total output P ower
80 70 60 P ower Diss ipation 45 60
E ff (%)
2 % 1 0.5 0.2 0.1 0.05 0.02 0.01 1 2 5 10 W 20 50 100 V S = 16V
50 E ffic ienc y 40 30 30
V S = 14.4V
20 10 0 0 10 20 30 40 50 60
AM MOD E VPP = 1 4.4V RL = 4 f= 1 kH z BW = 22 H z - 20 kH z(AES1 7)
15
0 100
70
80
90
Total Output P ower (W )
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TPS4100A - KL/Rev. 1.1/11.05
P diss (W )
Tripath Technology, Inc. - Technical Information
Application Information
GENERAL DESCRIPTION The TPS4100A is a 4-channel BTL (Bridge Tied Load) audio amplifier power stage that operates on a single supply voltage ranging from 10-26V. The device is targeted specifically to meet the demands of OEM and aftermarket automobile in-dash head units. With a single supply voltage of 25V, the device delivers four 100 Watt (saturated square wave) channels into 4 ohm. Since the TPS4100A is a switching amplifier, the average dissipation at low to medium output power is far superior to best in class AB amplifiers specifically designed for in-dash head units.
POWER SUPPLY REQUIREMENTS The device is configured to operate from a single supply voltage of 10-26V. This allows the device to operate from an automobile battery under various conditions including: battery voltage with the engine off, alternator voltage with engine running and boosted voltage operation up to 26V using a DC-DC converter or voltage booster. The sleep pin must be driven from a microcontroller or external 3.3V or 5.0V power supply.
AM MODE The TPS4100A is typically configured as a high power, high efficiency, four channel switching amplifier. The TPS4100A also has an additional amplifier mode named "AM Mode." By pulling the AM pin to a logic high level, the TPS4100A is configured as a Class B amplifier as opposed to the normal, Class-T amplifier. AM mode significantly reduces EMI generation since the output amplifiers are now operated in linear mode. Operating in Class B mode also reduces the TPS4100A efficiency especially at low to medium output powers. Due to this increased power dissipation, it is recommended that the AM mode is used for applications such as AM radio playback where the average output level is minimal and a switching amplifier would most effect radio reception. The operating supply range is also limited to 10V-16V due to the increased power dissipation. A DC to DC converter that is used to step up the battery voltage for Class T operation (for instance 14.4V 20V or above) should be disabled before entering AM Mode. This will ensure that the supply voltage in AM Mode is limited to the battery voltage thereby minimizing the device power dissipation. To avoid possible damage to the output stage, appropriate sequencing must be adhered to when activating or disabling AM Mode. The TPS4100A MUST be muted (MUTEB = high) during logic changes of the AM pin. To change from Class-T mode to AM Mode, the following procedure must be followed. With AM = Low and MUTEB = High MUTEB = Low AM = High MUTEB = High
To change from AM Mode to Class-T mode, the following procedure must be followed. With AM = High, MUTEB = High MUTEB = Low AM = Low MUTEB = High
Thus, MUTEB is low during any transition of the AM pin.
CIRCUIT BOARD LAYOUT When used in conjunction with a Class T controller the TPS4100A is a power (high current) amplifier that operates at relatively high switching frequencies. Therefore, amplifier outputs switch between the supply
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Tripath Technology, Inc. - Technical Information
voltage and ground at high speeds while driving high currents. This high-frequency digital signal is passed through an LC low-pass filter to recover the amplified audio signal. Since the amplifier must drive the inductive LC output filter and speaker loads, the amplifier outputs can be pulled above the supply voltage and below ground by the energy in the output inductance. To avoid subjecting the TPS4100A to potentially damaging voltage stress, it is critical to have a good printed circuit board layout. It is recommended that Tripath's layout and application circuit be used for all applications and only be deviated from after careful analysis of the effects of any changes. The following components are important to place near either their associated TPS4100A pins. The recommendations are ranked in order of layout importance, either for proper device operation or performance considerations. The capacitors, CBR, provide high frequency bypassing of the amplifier power supplies and will serve to reduce spikes and modulation of the power supply rails. Please note that bypassing requires a combination of capacitors for adequate stabilization. The output diodes, DO, are used to minimize overshoots/undershoots on the output node. Improper routing of these diodes will render them useless due to PCB trace inductance. Thus, these components must be located very close to the output pins with the "other side of the diode" routed directly to the appropriate VPP or PGND pin.
-
The capacitors, CS, provide high frequency bypassing of the amplifier power supplies. Please note that bypassing requires a combination of capacitors for adequate stabilization.
PROTECTION CIRCUITS The TPS4100A is guarded against over-current, over/under voltage, and over-temperature conditions. If the device goes into one of the various protection states, the FAULT pin goes to a logic HIGH state indicating a fault condition. When this occurs, all amplifier outputs are TRI-STATED and will float to VDD.
OVER-CURRENT PROTECTION An over-current fault occurs if more than approximately 12.5 amps (typical) of current flows from any of the amplifier output pins. This can occur if the speaker wires are shorted together, if one side of the speaker is shorted to ground, or if an output is connected to VPP. OVER AND UNDER VOLTAGE PROTECTION An over-voltage fault occurs if the supply voltage is increased above 30.0 volts (typical), 27.0 volts (minimum). This fault puts the amplifier into mute and resets automatically once the supply voltage is reduced below the hysteresis band. The TPS4100A also has built-in load dump protection. This circuit puts the amplifier into sleep mode if the supply voltage is increased above 30V. The TPS4100A is able to survive power supply spikes to 60V if the duration is less than 50mS. The TPS4100A is also equipped with under voltage protection. This circuit is activated if the supply voltage goes below 8.1 volts (typical) and causes the output to mute. Increasing the supply voltage above the hysteresis band (typically 9.5V) will bring the amplifier out of mute mode.
OVER-TEMPERATURE PROTECTION An over-temperature FAULT occurs if the junction temperature of the part exceeds 160C (typical). The thermal hysteresis is approximately 30C, therefore the fault will automatically clear when the junction temperature drops below 130C.
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SLEEP PIN (ACTIVE LOW) The SLEEPB (SLEEP) pin is a logic input that when pulled low puts the TPS4100A into a low quiescent current mode. This pin must be pulled up to an external 3.3V or 5V supply to activate (disable sleep mode) the TPS4100A. The sleep pin cannot be pulled up to VPP due to internal circuitry limitations. The amplifier takes approximately 500mS to come out of sleep. This period of time allows the input capacitor to charge fully assuming a value of 0.47uF. If the input capacitor size is increased, then additional time will be required to allow for the input capacitor to fully charge. To ensure that turn on is pop-free, the input capacitor must be fully charged before MUTEB is pulled high.
MUTEB PIN The MUTEB pin is a logic input that mutes the TPS4100A. Pulling this pin low activates the mute circuitry. Pulling the pin high enables output switching and amplification. Please note that the input stage is still biased at approximately 2.5V, even when MUTEB pin is low. This keeps the BIASCAP, CB and input coupling capacitors, CI, completely charged. This allows for a clean transition from mute to on, and vice-versa, which eliminates turn-on/off pops. Please note that DC calibration is done every time MUTEB transitions from low to high. The DC calibration takes approximately 6mS.
FAULT PIN The FAULT pin is a logic output that indicates various fault conditions within the device. These conditions include: over-voltage, under-voltage, over-current at any output, low charge pump voltage, low 5V regulator voltage, and over-temperature (junction temperature greater than approximately 160C). The FAULT pin is an open drain output. The recommended pull-up to an external 3.3V or 5V supply is 51k. Alternatively, this pin can be pulled up to VPP through a 51k resistor. A logic high on this pin indicates a fault condition. This pin has a 1mA maximum sink current capability.
OUTPUT FILTER DESIGN One advantage of Tripath amplifiers over PWM solutions is the ability to use higher-cutoff-frequency filters. This means any load-dependent peaking/droop in the 20kHz audio band potentially caused by the filter can be made negligible. This is especially important for applications where the user may select a 4 or 8 speaker. Furthermore, speakers are not purely resistive loads and the impedance they present changes over frequency and from speaker model to speaker model. The core material of the output filter inductor has an effect on the distortion levels produced by a TPS4100A amplifier. Tripath recommends low-mu type-2 iron powder cores because of their low loss and high linearity or high current capability bobbin types that will not saturate at peak currents below 9A. Recently, there have been a number of dual inductors designed specifically for bridged output switching amplifiers. These dual inductors are two inductors shielded by a common ferrite shield. They may be manufactured as common mode chokes with the windings wound in the same direction or as differential mode chokes with the windings wound in opposite directions. Since the ferrite reduces the energy storage capability of the inductor, it is important to ensure that the shielded dual inductor does not saturate at the maximum currents attainable by the TPS4100A. Dual inductors wound as common mode inductors may aid in reducing common mode noise to the load. They also may result in lower than initial inductances due to electric field cancellation effects. Tripath also recommends that an RC damper be used after the LC low-pass filter. No-load operation of a TPS4100A amplifier can create significant peaking in the LC filter, which produces strong resonant
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Tripath Technology, Inc. - Technical Information
currents that can overheat the integrated MOSFETs and/or other components. The RC dampens the peaking and prevents problems. It is highly recommended that the design process for a TPS4100A amplifier include an analysis of the interaction of intended speaker(s) with the LC filter and RC damper to ensure the desired frequency response is attained. Component values for the LC filter and RC damper may need to be altered from the Tripath suggestions to achieve the required response.
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Tripath Technology, Inc. - Technical Information
Package Information
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TPS4100A - KL/Rev. 1.1/11.05
Tripath Technology, Inc. - Technical Information
Tripath Technology Inc. reserves the right to make changes without further notice to any products herein to improve reliability, function or design. Tripath does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. TRIPATH'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN CONSENT OF THE PRESIDENT OF TRIPATH TECHNOLOGY INC. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in this labeling, can be reasonably expected to result in significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
Contact Information
TRIPATH TECHNOLOGY, INC 2560 Orchard Parkway, San Jose, CA 95131 408.750.3000 - P 408.750.3001 - F For more Sales Information, please visit us @ www.tripath.com/cont_s.htm For more Technical Information, please visit us @ www.tripath.com/data.htm
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TPS4100A - KL/Rev. 1.1/11.05

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