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NJU8754
PRELIMINARY
Analog Signal Input Monaural Class D Power Amplifier
GENERAL DESCRIPTION The NJU8754 is an analog signal input monaural class D power amplifier. The NJU8754 includes Inversion operatinal amplifier input circuit, PWM modulator, an output-short protector and a low voltage detector. The NJU8754 incorporates BTL amplifier, which eliminate AC coupling capacitors, capable of driving up to 0.6W at 3.6V supply voltage with simple external LC low-pass filters. The NJU8754 features high power-efficiency by class-D operation and very small package, and is suited for cellular phone, PDA, etc. FEATURES Monaural Analog Signal Input Monaural BTL Output :1.2W at 5V into 8Ohms :0.6W at 3.6V into 8Ohms Standby(Hi-Z), Mute Control Built-in Short Protector Built-in Low Voltage Detector Operating Voltage :2.7 ~ 5.25V CMOS Technology Package Outline :SSOP10, QFN20 PACKAGE OUTLINE
NJU8754V
NJU8754KM1
PIN CONFIGURATION
15 16
NC OUTP VDDO OUTN NC QFN20
11 10
VDD IN COM MUTE STBY
1 2 3 4 5 SSOP10
10 9 8 7 6
VSS OUTP VDDO OUTN VSS
VSS VSS NC VDD NC
20
VSS VSS NC STBY NC
6
Ver.2003-03-12
NC IN COM MUTE NC
1
5
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NJU8754
BLOCK DIAGRAM
VDD
VSS
IN
+ Pulse Width Modulator
OUTP VDDO OUTN
COM
+
Short Protection
Soft Start
Control
Logic
Low BATT Protection
MUTE
STBY
PIN DESCRIPTION No. SSOP10 1 2 3 QFN20 19 2 3 SYMBOL VDD IN COM I/O - I - FUNCTION
Power supply : VDD=3.6V Signal input Analog common Mute control 4 4 MUTE I Low : Mute ON High : Mute OFF Standby control 5 7 STBY I Low : Standby ON High : Standby OFF 6 9,10 VSS - Power GND : VSS=0V 7 12 OUTN O Negative output 8 13 VDDO - Output power supply 9 14 OUTP O Positive output 10 16,17 VSS - Power GND : VSS=0V - 1,5,6,8,11,15,18,20 NC - Non connection *The relations of "VSS= 0V" and "VDD= VDDO" must be maintained. *VSS(SSOP10:Pin No.6,10, QFN20:Pin No.9,10,16,17) should be connected at a nearest point to the IC. *VDDO(SSOP10:Pin No.8, QFN20:Pin No.13) should be connected at a nearest point to the IC. *MUTE(SSOP10, QFN20:Pin No.4) and STBY(SSOP10:Pin No.5, QFN20:Pin No.7) must be connected to VDD, when these pins are not used.
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Ver.2003-03-12
NJU8754 NJU3555
FUNCTIONAL DESCRIPTION (1) Signal Output The OUTP and OUTN generate PMW output signal, which will be converted to analog signal via external 2nd-order or higher LC filter. A switching regulator with a high response against a voltage fluctuation is the best selection for the VDDO, which is the power supply for output driver. To obtain better T.H.D. performance, the stabilization of the power is required. (2) Standby By setting the STBY pin to "L", the standby mode is enabled. In the standby mode, the entire functions of the NJU8754 enter a low-power state, and the output pins(OUTP and OUTN) are in high impedance. (3) Mute By setting the MUTE pin to "L", the Mute function is enabled, and the output pins(OUTP and OUTN) output square wave(Duty: 50%). (4) Low Voltage Detector When the power supply voltage drops down to below VDD(MIN), the internal oscillation is halted not to generate unwanted frequency, and the output pins(OUTP and OUTN) become in high impedance. (5) Short Protection Circuit The short protector, which protects the NJU8754 from high short-circuit current, turns off the output driver. After about 5 seconds from the protection, the NJU8754 returns to normal operation. The short protector is enabled in response to following accidents. Short between OUTP and OUTN Short between OUTP and VSS Short between OUTN and VSS The detectable current and the period for the protection depend on the power supply voltage and ambient temperature. Note 2) The short protector is not effective for a long term short-circuit but for an instantaneous accident. Continuous high-current may cause permanent damage to NJU8754. Note 1)
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NJU8754
ABSOLUTE MAXIMUM RATINGS (Ta=25C) PARAMETER Supply Voltage Input Voltage Operating Temperature Storage Temperature Power Dissipation SYMBOL VDD VDDO Vin Topr Tstg PD RATING -0.3 ~ +5.5 -0.3 ~ +5.5 -0.3 ~ VDD+0.3 -40 ~ +85 -40 ~ +125 250 (SSOP10) TBD(QFN20) UNIT V V V C C mW
Note 1) All voltage are relative to "VSS= 0V" reference. Note 2) The LSI must be used inside of the "Absolute maximum ratings". Otherwise, a stress may cause permanent damage to the LSI. Note 3) De-coupling capacitors for VDD-VSS and VDDO-VSS should be connected for stable operation. Note 4) Power Dissipation The class-D amplifiers are more power efficient, and dissipate power less than general analog-amplifiers. In theory, the NJU8754 actualize quite high output-power such as 1.2W at =5V operation with 8ohms load, it looks as if the NJU8754 exceeds the absolute maximum rating of the power dissipation. However, in practice, the effective output-power of usual music sound is only about 1/10 of its maximum output power, thus it may never exceed the absolute maximum rating. The maximum power dissipation in the system is calculated, as shown below. Pdmax(W) = (Tjmax(C) - Ta(C)) /ja Pdmax: Maximum Power Dissipation, Tjmax: Junction Temperature = 125C Ta: Ambient Temperature, ja: Thermal Resistance of package(SSOP10) = 400C/W Power dissipation of the NJU8754 itself is calculated, as shown below. Pd(W) = PO(W) X RO() / RL() + PdIC(W) Pd: Power Dissipation, PO: Output Power, RO: Internal Resistance(output driver) RL: Load Resistance, PdIC: Power of internal circuit
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Ver.2003-03-12
NJU8754 NJU3555
ELECTRICAL CHARACTERISTICS (Ta=25C, VDD=VDDO= 3.6V, VSS= 0V, Input Signal=1kHz, Input Signal Level=200mVrms, Frequency Band=20Hz~20kHz, Load Impedance=8, 2nd-order 34kHz LC Filter(Q=0.85)) PARAMETER VDD,VDDO Supply Voltage Input Impedance Voltage Gain Output Power Efficiency Output THD SYMBOL VDD ZIN AV Eeff THD CONDITIONS IN pin Output THD=10% VDD=VDDO=5.0V, Po=600mW VDD=VDDO=3.6V, Po=300mW VDD=VDDO=5.0V Output THD=10% VDD=VDDO=3.6V Output THD=10% A weight VDD=VDDO=5.0V No Filter, No Load VDD=VDDO=3.6V No Filter, No Load MUTE, STBY pins MUTE, STBY pins MUTE, STBY pins MIN 2.7 80 TYP 3.6 20 23 83 0.05 0.07 1.2 W 0.6 75 80 4 2.5 0.7VDD 0 1 6 mA 5 VDD 0.3VDD 0.1 V V A dB A MAX 5.25 0.08 0.1 UNIT V k dB % % Note
4
Output Power S/N Operating Current (Standby) Operating Current (No signal input) Input Voltage Input Leakage Current
Po SN IST IDD VIH VIL ILK
Note 5)
Test system of the output THD and S/N The output THD and S/N are tested in the system shown in Figure1, where a 2nd-order LC LPF and another filter incorporated in an audio analyzer are used.
Input Signal
NJU8754
2nd-order LC LPF
Filter 20kHz (AES17)
THD Measuring Apparatus
NJU8754 Test Board Figure 1. Output THD and S/N Test System
Audio Analyzer
2nd-order LPF Filters
: fc=34kHz / Refer to "Typical Application Circuit". : 22Hz HPF + 20kHz LPF(AES17) (with the A-Weight filter for S/N and Dynamic-range tests)
Ver.2003-03-12
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NJU8754
TYPICAL APPLICATION CIRCUIT
10F 0.1F 22H
VDD
VDD(1)
OUTP(9)
1F 22H
NJU8754
VSS(10)
2.2F
8 Speaker
1F
OUTN(7) VDDO(8) VSS(6)
0.1F 47F
IN
10F
IN(2) COM(3)
VDD
MUTE(4) STBY(5) SSOP10
10F 0.1F 22H
VDD
VDD(19)
OUTP(14)
1F 22H
NJU8754
VSS(16,17)
2.2F
8 Speaker
1F
OUTN(12) VDDO(13) VSS(9,10)
0.1F 47F
IN
10F
IN(2) COM(3)
VDD
MUTE(4) STBY(7) QFN20 Note 6) Note 7) Note 8) De-coupling capacitors must be connected between each power supply pin and GND. The capacity value should be adjusted on the application circuit and the operation temperature. It may malfunction if capacity value is small. The power supply for VDDO requires fast driving response performance such as a switching regulator for better THD. THD performance becomes worse by ripple if the capacity of De-coupling capacitor is small. The above circuit shows only application example and does not guarantee the any electrical characteristics. Therefore, please test the circuit carefully to fit your application. The cutoff frequency of the LC filter influences the quality of sound. The Q factor of the LC filter must be less than "1". Otherwise, the operating current increases when the frequency of input signal is closed to the cutoff frequency. The transition time for MUTE and STBY signals must be less than 100s. Otherwise, a malfunction may be occurred. (1) - (19) indicates pin number.
Note 9) Note10)
[CAUTION] The specifications on this databook are only given for information , without any guarantee as regards either mistakes or omissions. The application circuits in this databook are described only to show representative usages of the product and not intended for the guarantee or permission of any right including the industrial rights.
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Ver.2003-03-12

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