View MAX4364_143571.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-2387; Rev 1; 10/02
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
General Description
The MAX4364/MAX4365 are bridged audio power amplifiers intended for portable audio devices with internal speakers. The MAX4364 is capable of delivering 1.4W from a single 5V supply and 500mW from a single 3V supply into an 8 load. The MAX4365 is capable of delivering 1W from a single 5V supply and 450mW from a single 3V supply into an 8 load. The MAX4364/MAX4365 feature 0.04% THD + N at 1kHz, 68dB PSRR at 217Hz and only 10nA of supply current in shutdown mode. The MAX4364/MAX4365 bridged outputs eliminate the need for output-coupling capacitors, minimizing external component count. The MAX4364/MAX4365 also include internal DC bias generation, clickless operation, short-circuit and thermal-overload protection. Both devices are unity-gain stable, with the gain set by two external resistors. The MAX4364 is available in a small 8-pin SO package. The MAX4365 is available in tiny 8-pin thin QFN (3mm 3mm 0.8mm) and MAX packages. o 1.4W into 8 Load (MAX4364) o 1W into 8 Load (MAX4365) o 0.04% THD + N at 1kHz o 68dB PSRR at 217Hz o 2.7V to 5.5V Single-Supply Operation o 5mA Supply Current o Low-Power, 10nA Shutdown Mode o Pin Compatible with the LM4861/LM4862/LM4864 (MAX4364) o Clickless Power-Up and Shutdown o Thermal-Overload and Short-Circuit Protection o Available in Thin QFN, MAX, and SO Packages
Features
MAX4364/MAX4365
Ordering Information
PART MAX4364ESA MAX4365EUA MAX4365ETA TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 8 Thin QFN-EP* TOP MARK -- -- ACD
Applications
Cellular Phones PDAs Two-Way Radios General-Purpose Audio
*EP = Exposed paddle. Pin Configurations appear at end of data sheet.
Typical Application Circuit/Functional Diagram
VCC 6 VCC 50k 2 BIAS OUT- 8 CBIAS 50k
CLICKLESS/POPLESS SHUTDOWN CONTROL
SHDN 1
3 IN+ CIN AUDIO INPUT RIN
10k
10k OUT+ 5
4 IN-
MAX4364
GND RF
7
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
ABSOLUTE MAXIMUM RATINGS
VCC, OUT_ to GND...................................................-0.3V to +6V IN+, IN-, BIAS, SHDN to GND....................-0.3V to (VCC + 0.3V) Output Short Circuit (OUT+ to OUT-) (Note 1)...........Continuous Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.1mW/C above +70C) ..............330mW 8-Pin Thin QFN (derate 24.4mW/C above +70C) ....1951mW 8-Pin SO (derate 5.88mW/C above +70C).................471mW Note 1: Continuous power dissipation must also be observed.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Junction Temperature ......................................................+150C Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
ELECTRICAL CHARACTERISTICS--5V
(VCC = 5V, RL = , CBIAS = 1F to GND, SHDN = GND, TA = +25C, unless otherwise noted.) (Note 2)
PARAMETER Supply Voltage Range SYMBOL VCC CONDITIONS Inferred from PSRR test MAX4364 Supply Current ICC (Note 3) MAX4364, TA = TMIN to TMAX MAX4365 MAX4365, TA = TMIN to TMAX Shutdown Supply Current ISHDN SHDN = VCC VIH SHDN Threshold VIL Common-Mode Bias Voltage Output Offset Voltage Power-Supply Rejection Ratio VBIAS VOS PSRR (Note 4) IN- = OUT+, IN+ = BIAS (Note 5) VCC = 2.7V to 5.5V VRIPPLE = 200mVP-P, RL = 8 RL = 8, THD + N = 1%, fIN = 1kHz (Note 6) DC 217Hz 1kHz MAX4364 MAX4365 MAX4364, POUT = 1W MAX4365, POUT = 750mW 1200 800 55 VCC/2 5% VCC/2 1 75 68 58 1400 mW 1000 0.04 % 0.1 12 600 160 15 tPU tSHDN tENABLE 50 10 50 VRMS mA
o o
MIN 2.7
TYP 7 5 0.01
MAX 5.5 13 17 8 11 4
UNITS V
mA
A
VCC x 0.7 V VCC x 0.3 VCC/2 + 5% 10 V mV dB
Output Power
POUT
Total Harmonic Distortion Plus Noise Noise Short-Circuit Current Thermal Shutdown Threshold Thermal Shutdown Hysteresis Power-Up Time Shutdown Time Enable Time from Shutdown
THD + N
AV = -2V/V, RL = 8, fIN = 1kHz (Notes 7, 8)
fIN = 10kHz, BW = 22Hz to 22kHz ISC OUT+ to OUT- (Note 9)
C C
ms s ms
2
_______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
ELECTRICAL CHARACTERISTICS--3V
(VCC = 3V, RL = , CBIAS = 1F to GND, SHDN = GND, TA = +25C, unless otherwise noted.) (Note 2)
PARAMETER Supply Current Shutdown Supply Current Output Power SYMBOL ICC ISHDN POUT (Note 3) SHDN = VCC RL = 8, THD + N = 1%, fIN = 1kHz (Note 6) MAX4364 MAX4365 400 350 CONDITIONS MAX4364 MAX4365 MIN TYP 6 4.5 10 500 mW 450 0.05 % 0.08 MAX UNITS mA nA
MAX4364/MAX4365
Total Harmonic Distortion Plus Noise
THD + N
MAX4364, POUT = 400mW AV = -2V/V, RL = 8, fIN = 1kHz (Notes 7, 8) MAX4365, POUT = 400mW
Note 2: All specifications are 100% tested at TA = +25C. Note 3: Quiescent power-supply current is specified and tested with no load on the outputs. Quiescent power-supply current depends on the offset voltage when a practical load is connected to the amplifier. Note 4: Common-mode bias voltage is the voltage on BIAS and is nominally VCC/2. Note 5: Maximum differential-output offset voltage is tested in a unity-gain configuration. VOS = VOUT+ - VOUT-. Note 6: Output power is specified by a combination of a functional output-current test, and characterization analysis. Note 7: Guaranteed by design, not production tested. Note 8: Measurement bandwidth for THD + N is 22Hz to 22kHz. Note 9: Extended short-circuit conditions result in a pulsed output.
Typical Operating Characteristics
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc01
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc02
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V AV = 20V/V RL = 8 THD + N (%) 1 0.25W
MAX4364 toc03
10 VCC = 5V AV = 2V/V RL = 8 THD + N (%) 1
10 VCC = 5V AV = 4V/V RL = 8 THD + N (%) 1
10
0.1
0.25W 0.5W
0.1
0.25W 0.5W 1W
0.1 1W 0.5W
0.01 0 100
1W 1k 10k FREQUENCY (Hz)
0.01 0 100 1k 10k FREQUENCY (Hz)
0.01 0 100 1k 10k FREQUENCY (Hz)
_______________________________________________________________________________________
3
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
Typical Operating Characteristics (continued)
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc04
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc05
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 3V AV = 20V/V RL = 8 THD + N (%) 1 0.25W
MAX4364 toc06 MAX4364 toc12 MAX4364 toc09
10 VCC = 3V AV = 2V/V RL = 8 THD + N (%) 1 0.4W 0.1 0.25W
10 VCC = 3V AV = 4V/V RL = 8 THD + N (%) 1
10
0.1
0.25W
0.1
0.4W
0.4W 0.01 0 100 1k 10k FREQUENCY (Hz) 0.01 0 100 1k 10k FREQUENCY (Hz) 0.01 0 100 1k 10k FREQUENCY (Hz)
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc07
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc08
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
100 VCC = 3V AV = 2V/V RL = 8
100 VCC = 5V AV = 2V/V RL = 8
100 VCC = 5V AV = 4V/V RL = 8 20kHz 20Hz 0.1 1kHz
10 THD + N (%)
10 THD + N (%)
10 THD + N (%)
1 20kHz 0.1 1kHz 20Hz
1
1 20kHz 0.1 1kHz
0.01
0.01
0.01
20Hz
0.001 0 40 200 520 1000 1650 2450 OUTPUT POWER (mW)
0.001 0 40 200 520 1000 1650 2450 OUTPUT POWER (mW)
0.001 0 20 190 525 1000 1700 2500 OUTPUT POWER (mW)
MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc10
MAX4364 OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4364 toc11
MAX4364 OUTPUT POWER vs. LOAD RESISTANCE
3000 VCC = 5V fIN = 1kHz
100 VCC = 3V AV = 4V/V RL = 8
2500
RL = 8 fIN = 1kHz 10% THD + N
10 THD + N (%)
2000 OUTPUT POWER (mW)
2400 OUTPUT POWER (mW)
1
20kHz
1500
1800 10% THD + N
0.1 1kHz
1000
1200
0.01
20Hz
500
1% THD + N
600 1% THD + N
0.001 0 40 200 520 1000 1650 2440 OUTPUT POWER (mW)
0 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V)
0 0 10 20 30 40 50 LOAD RESISTANCE ()
4
_______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
MAX4364 OUTPUT POWER vs. LOAD RESISTANCE
MAX4364 toc13
MAX4364/MAX4365
MAX4364 POWER DISSIPATION vs. OUTPUT POWER
MAX4364 toc14
MAX4364 POWER DISSIPATION vs. OUTPUT POWER
270 POWER DISSIPATION (mW) 240 210 180 150 120 90 60 30 0 VCC = 3V fIN = 1kHz RL = 8 0 100 200 300 400 500
MAX4364 toc15
1200 1000 OUTPUT POWER (mW) 800 600 400 200 1% THD + N 0 0 10 20 30 10% THD + N
VCC = 3V fIN = 1kHz
700 630 POWER DISSIPATION (mW) 560 490 420 350 280 210 140 70 0 VCC = 5V fIN = 1kHz RL = 8 0 300 600 900 1200
300
40
50
1500
LOAD RESISTANCE ()
OUTPUT POWER (mW)
OUTPUT POWER (mW)
MAX4364 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4364 toc16
MAX4364 SUPPLY CURRENT vs. TEMPERATURE
VCC = 5V 9 SUPPLY CURRENT (mA)
MAX4364 toc17
MAX4364 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4364 toc18
9.0 8.5 SUPPLY CURRENT (mA) 8.0 7.5 7.0 6.5 6.0 2.7 3.4 4.1 4.8
10
12 10 SUPPLY CURRENT (nA) 8 6 4 2 0
8
7
6
5 5.5 -40 -15 10 35 60 85 SUPPLY VOLTAGE (V) TEMPERATURE (C)
2.7
3.4
4.1
4.8
5.5
SUPPLY VOLTAGE (V)
MAX4364 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
VCC = 5V 80 SUPPLY CURRENT (nA)
MAX4364 toc19
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc20
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V AV = 4V/V RL = 8 THD + N (%) 1 0.25W 0.5W 0.1 0.75W
MAX4364 toc21
100
10 VCC = 5V AV = 2V/V RL = 8 THD + N (%) 1 0.25W 0.5W 0.1 0.75W
10
60
40
20
0 -40 -15 10 35 60 85 TEMPERATURE (C)
0.01 0 100 1k 10k FREQUENCY (Hz)
0.01 0 100 1k 10k FREQUENCY (Hz)
_______________________________________________________________________________________
5
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
Typical Operating Characteristics (continued)
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc22
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc23
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 3V AV = 4V/V RL = 8 THD + N (%) 1
MAX4364 toc24
10 VCC = 5V AV = 20V/V RL = 8 THD + N (%) 1 0.5W 0.25W
10 VCC = 3V AV = 2V/V RL = 8 THD + N (%) 1
10
0.75W 0.1
0.25W 0.1 0.4W
0.4W 0.1 0.25W 0.01
0.01 0 100 1k 10k FREQUENCY (Hz)
0.01 0 100 1k 10k FREQUENCY (Hz)
0
100
1k
10k
FREQUENCY (Hz)
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4364 toc25
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc26
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
VCC = 5V AV = 4V/V RL = 8 20kHz THD + N (%) 20Hz
MAX4364 toc27
10 VCC = 3V AV = 20V/V RL = 8 THD + N (%) 1 0.25W
100 VCC = 5V AV = 2V/V RL = 8 20kHz THD + N (%) 1 20Hz
100
10
10
1
0.1
0.4W
0.1 1kHz 0.01
0.1 1kHz 0.01
0.01 0 100 1k 10k FREQUENCY (Hz)
0.001 0 200 300 500 700 1000 1300 1600 2000 2400 OUTPUT POWER (mW)
0.001 500 750 1000 1300 1600 2000 2400 OUTPUT POWER (mW)
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc28
MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4364 toc29
MAX4365 OUTPUT POWER vs. SUPPLY VOLTAGE
RL = 8 fIN = 1kHz
MAX4364 toc30
100 VCC = 3V AV = 2V/V RL = 8
100 VCC = 3V AV = 4V/V RL = 8 20kHz 20Hz 0.1 1kHz
2500
10 THD + N (%)
10 THD + N (%)
2000 OUTPUT POWER (mW) 10% THD + N
1 20Hz 0.1
20kHz
1
1500
1000
0.01
1kHz
0.01
500 1% THD + N
0.001 0 125 200 250 325 400 500 600 725 800 1000 OUTPUT POWER (mW)
0.001 0 125 200 250 325 400 500 600 725 850 1000 OUTPUT POWER (mW)
0 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V)
6
_______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
MAX4365 OUTPUT POWER vs. LOAD RESISTANCE
VCC = 5V fIN = 1kHz
MAX4364 toc31
MAX4364/MAX4365
MAX4365 OUTPUT POWER vs. LOAD RESISTANCE
MAX4364 toc32
MAX4365 POWER DISSIPATION vs. OUTPUT POWER
MAX4364 toc33
1200 1000 OUTPUT POWER (mW) 800 600 400 200 0 0 10 20 30 40
1200 1000 OUTPUT POWER (mW) 800 600 400 200 1% THD + N 0 10% THD + N VCC = 3V fIN = 1kHz
800
POWER DISSIPATION (mW)
600
400
200 VCC = 5V RL = 8 fIN = 1kHz 0
50
0
10
20
30
40
50
0
300
600
900
1200
1500
LOAD RESISTANCE ()
LOAD RESISTANCE ()
OUTPUT POWER (mW)
MAX4365 POWER DISSIPATION vs. OUTPUT POWER
MAX4364 toc34
MAX4365 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4364 toc35
MAX4365 SUPPLY CURRENT vs. TEMPERATURE
VCC = 5V
MAX4364 toc36
250
7
7
POWER DISSIPATION (mW)
200
SUPPLY CURRENT (mA)
150
5
SUPPLY CURRENT (mA) 2.7 3.4 4.1 4.8 5.5
6
6
5
100 VCC = 3V RL = 8 fIN = 1kHz 0 100 200 300 400 500
4
50
4
0 OUTPUT POWER (mW)
3 SUPPLY VOLTAGE (V)
3 -40 -15 10 35 60 85 TEMPERATURE (C)
MAX4365 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4364 toc37
MAX4365 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
VCC = 5V 70 SUPPLY CURRENT (nA) 60 50 40 30 20
MAX4364 toc38
12 10 SUPPLY CURRENT (nA) 8 6 4 2 0 2.7 3.4 4.1 4.8
80
10 0 5.5 -40 -15 10 35 60 85 SUPPLY VOLTAGE (V) TEMPERATURE (C)
_______________________________________________________________________________________
7
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
Typical Operating Characteristics (continued)
(VCC = 5V, THD + N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.)
GAIN AND PHASE vs. FREQUENCY
80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 10
MAX4364 toc39
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
RL = 8 VRIPPLE = 200mVP-P
MAX4364 toc40
-20 -30 -40 PSRR (dB) -50 -60 -70
GAIN/PHASE (dB/DEGREES)
AV = 1000V/V -80 100 1k 10k 100k 1M 10M 10 100 1k FREQUENCY (Hz) 10k 100k FREQUENCY (Hz)
Pin Description
PIN MAX4364 SO 1 2 3 4 5 6 7 8 MAX4365 MAX/QFN 7 1 2 4 5 6 3 8 SHDN BIAS IN+ INOUT+ VCC GND OUTActive-High Shutdown. Connect SHDN to GND for normal operation. DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect CBIAS capacitor from BIAS to GND. Noninverting Input Inverting Input Bridged Amplifier Positive Output Power Supply Ground Bridged Amplifier Negative Output NAME FUNCTION
8
_______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
Detailed Description
The MAX4364/MAX4365 bridged audio power amplifiers can deliver 1.4W into 8 (MAX4364) or 1W into 8 (MAX4365) while operating from a single 5V supply. These devices consist of two high-output-current op amps configured as a bridge-tied load (BTL) amplifier (see Typical Application Circuit/Functional Diagram). The gain of the device is set by the closed-loop gain of the input op amp. The output of the first amplifier serves as the input to the second amplifier, which is configured as an inverting unity-gain follower in both devices. This results in two outputs, identical in magnitude, but 180 out of phase.
+1 VOUT(P-P)
MAX4364/MAX4365
2 x VOUT(P-P)
-1
VOUT(P-P)
Figure 1. Bridge-Tied Load Configuration
BIAS
The MAX4364/MAX4365 feature an internally generated common-mode bias voltage of VCC/2 referenced to GND. BIAS provides both click-and-pop suppression and the DC bias level for the audio signal. BIAS is internally connected to the noninverting input of one amplifier, and should be connected to the noninverting input of the other amplifier for proper signal biasing (see Typical Application Circuit/Functional Diagram). Choose the value of the bypass capacitor as described in the BIAS Capacitor section.
the device is twice the closed-loop gain of the input amplifier. The effective gain is given by: A VD = 2 x RF RIN
Substituting 2 VOUT(P-P) into the following equations yields four times the output power due to doubling of the output voltage. VRMS = VOUT(P-P) 22
Shutdown
The MAX4364/MAX4365 feature a 10nA, low-power shutdown mode that reduces quiescent current consumption. Pulling SHDN high disables the device's bias circuitry, the amplifier outputs go high impedance, and BIAS is driven to GND. Connect SHDN to GND for normal operation.
2 V POUT = RMS RL
Current Limit
The MAX4364/MAX4365 feature a current limit that protects the device during output short circuit and overload conditions. When both amplifier outputs are shorted to either VCC or GND, the short-circuit protection is enabled and the amplifier enters a pulsing mode, reducing the average output current to a safe level. The amplifier remains in this mode until the overload or short-circuit condition is removed.
Since the differential outputs are biased at midsupply, there is no net DC voltage across the load. This eliminates the need for DC-blocking capacitors required for single-ended amplifiers. These capacitors can be large, expensive, consume board space, and degrade low-frequency performance.
Power Dissipation
Under normal operating conditions, the MAX4364/ MAX4365 can dissipate a significant amount of power. The maximum power dissipation for each package is given in the Absolute Maximum Ratings section under Continuous Power Dissipation or can be calculated by the following equation: PDISSPKG(MAX ) = TJ(MAX ) - TA JA
Applications Information
Bridge-Tied Load
The MAX4364/MAX4365 are designed to drive a load differentially in a BTL configuration. The BTL configuration (Figure 1) offers advantages over the single-ended configuration, where one side of the load is connected to ground. Driving the load differentially doubles the output voltage compared to a single-ended amplifier under similar conditions. Thus, the differential gain of
where TJ(MAX) is +150C, TA is the ambient temperature and JA is the reciprocal of the derating factor in C/W as specified in the Absolute Maximum Ratings section. For example, JA of the MAX package is 222C/W.
9
_______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. The maximum power dissipation for a given VCC and load is given by the following equation: PDISS(MAX) = 2VCC2 RL
2
2V PIN = VCC PEAK RL The efficiency of the MAX4364/MAX4365 is: P = OUT = PIN POUTRL 2 2VCC
If the power dissipation for a given application exceeds the maximum allowed for a given package, reduce VCC, increase load impedance, decrease the ambient temperature or add heat sinking to the device. Large output, supply, and ground PC board traces improve the maximum power dissipation in the package. Thermal-overload protection limits total power dissipation in the MAX4364/MAX4365. When the junction temperature exceeds +160C, the thermal protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by 15C. This results in a pulsing output under continuous thermal overload conditions as the device heats and cools. The MAX4365 QFN package features an exposed thermal pad on its underside. This pad lowers the thermal resistance of the package by providing a direct heat conduction path from the die to the PC board. Connect the exposed thermal pad to circuit ground by using a large pad, ground plane, or multiple vias to the ground plane.
The device efficiency values in Table 1 are calculated based on the previous equation and do include the effects of quiescent current. Note that efficiency is low at low output-power levels, but remains relatively constant at normal operating, output-power levels.
Component Selection
Gain-Setting Resistors External feedback components set the gain of both devices. Resistors RF and RIN (see Typical Application Circuit/Functional Diagram) set the gain of the amplifier as follows: A VD = 2 x RF RIN
Efficiency
The efficiency of the MAX4364/MAX4365 is calculated by taking the ratio of the power delivered to the load to the power consumed from the power supply. Output power is calculated by the following equations: V POUT = PEAK 2RL
2
Optimum output offset is achieved when RF = 20k. Vary the gain by changing the value of RIN. When using the MAX4364/MAX4365 in a high-gain configuration (greater than 8V/V), a feedback capacitor may be required to maintain stability (see Figure 2). CF and RF limit the bandwidth of the device, preventing high-frequency oscillations. Ensure that the pole created by CF and RF is not within the frequency band of interest. Input Filter The input capacitor (CIN), in conjunction with RIN forms a highpass filter that removes the DC bias from an incoming signal. The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero source impedance, the -3dB point of the highpass filter is given by: -3dB = 1 2RINCIN
where VPEAK is half the peak-to-peak output voltage. In BTL amplifiers, the supply current waveform is a fullwave rectified sinusoid with the magnitude proportional to the peak output voltage and load. Calculate the supply current and power drawn from the power supply by the following: ICC = 2VPEAK RL
Choose RIN according to the Gain-Setting Resistors section. Choose CIN such that f-3dB is well below the lowest frequency of interest. Setting f -3dB too high affects the low-frequency response of the amplifier. Use capacitors whose dielectrics have low-voltage coeffi-
10
______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
VCC
6 VCC 50k 2 BIAS OUTCBIAS 50k 8 CLICKLESS/ POPLESS SHUTDOWN CONTROL SHDN 1
3
IN+
10k 10k OUT+ 5
CIN AUDIO INPUT
RIN
4
IN-
MAX4364 MAX4365 RF
GND
7
CF
Figure 2. High-Gain Configuration
Table 1. Efficiency in a 5V, 8 BTL System
OUTPUT POWER (W) 0.25 0.50 0.75 1.00 1.25 1.40 INTERNAL POWER DISSIPATION (W) 0.55 0.63 0.63 0.59 0.53 0.48 EFFICIENCY (%) 31.4 44.4 54.4 62.8 70.2 74.3
3.5kHz). In addition, speakers used in portable devices typically have a poor response below 150Hz. Taking these two factors into consideration, the input filter may not need to be designed for a 20Hz to 20kHz response, saving both board space and cost due to the use of smaller capacitors. BIAS Capacitor The BIAS bypass capacitor, CBIAS, improves PSRR and THD + N by reducing power-supply noise at the common-mode bias node, and serves as the primary clickand-pop suppression mechanism. CBIAS is fed from an internal 25k source, and controls the rate at which the common-mode bias voltage rises at startup and falls during shutdown. For optimum click-and-pop suppression, ensure that the input capacitor (C IN ) is fully charged (ten time constants) before CBIAS. The value of CBIAS for best click-and-pop suppression is given by: C R CBIAS 10 IN IN 25k In addition, a larger CBIAS value yields higher PSRR.
cients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in an increase distortion at low frequencies. Other considerations when designing the input filter include the constraints of the overall system, the actual frequency band of interest and click-and-pop suppression. Although high-fidelity audio calls for a flat gain response between 20Hz and 20kHz, portable voicereproduction devices such as cellular phones and twoway radios need only concentrate on the frequency range of the spoken human voice (typically 300Hz to
______________________________________________________________________________________
11
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
Clickless/Popless Operation Proper selection of AC-coupling capacitors (CIN) and CBIAS achieves clickless/popless shutdown and startup. The value of CBIAS determines the rate at which the midrail bias voltage rises on startup and falls when entering shutdown. The size of the input capacitor also affects clickless/popless operation. On startup, CIN is charged to its quiescent DC voltage through the feedback resistor (RF) from the output. This current creates a voltage transient at the amplifier's output, which can result in an audible pop. Minimizing the size of CIN reduces this effect, optimizing click-and-pop suppression. Supply Bypassing Proper supply bypassing ensures low-noise, low-distortion performance. Place a 0.1F ceramic capacitor in parallel with a 10F ceramic capacitor from V CC to GND. Locate the bypass capacitors as close to the device as possible.
RF
AUDIO INPUT
1H
MAX5407
W3 RIN IN- MAX4364 CIN
OUT+
4L
MAX4365
OUT-
Figure 3. MAX4364/MAX4365 and MAX5160 Volume Control Circuit
tion passes the audio signal unattenuated. Setting the wiper to the lowest position fully attenuates the input.
Layout Considerations
Good layout improves performance by decreasing the amount of stray capacitance and noise at the amplifier's inputs and outputs. Decrease stray capacitance by minimizing PC board trace lengths, using surface-mount components and placing external components as close to the device as possible. Also refer to the Power Dissipation section for heatsinking considerations.
Adding Volume Control
The addition of a digital potentiometer provides simple volume control. Figure 3 shows the MAX4364/MAX4365 with the MAX5407 log taper digital potentiometer used as an input attenuator. Connect the high terminal of the MAX5407 to the audio input, the low terminal to ground and the wiper to CIN. Setting the wiper to the top posi-
Pin Configurations
TOP VIEW
SHDN BIAS IN+ 1 2 8 7 OUTGND VCC OUT+
Chip Information
MAX4364 TRANSISTOR COUNT: 772 MAX4365 TRANSISTOR COUNT: 768 PROCESS: BiCMOS
MAX4364
3 6 5 IN- 4
SO
BIAS IN+ GND
1 2
8 7
OUTSHDN VCC OUT+
MAX4365
3 6 5 IN- 4
MAX/QFN
12
______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
SOICN .EPS
MAX4364/MAX4365
INCHES DIM A A1 B C e E H L MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050
MILLIMETERS MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D A e B A1 L C
0-8
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
______________________________________________________________________________________
13
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4364/MAX4365
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
6, 8, &10L, QFN THIN.EPS
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
0.25 MIN 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T633-1 T833-1 T1033-1 N 6 8 10 D2 1.500.10 1.500.10 1.500.10 E2 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.50 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEED-3 b 0.400.05 0.300.05 0.250.05 [(N/2)-1] x e 1.90 REF 1.95 REF 2.00 REF
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
14
______________________________________________________________________________________
1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
8LUMAXD.EPS
MAX4364/MAX4365
8
4X S
8
INCHES DIM A A1 A2 b c D e E H MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1 0.60.1
E
H
1
0.60.1
1
D
L
S
BOTTOM VIEW
0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
e
c b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
J
1 1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX4364

	To Download MAX4364 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .