NJU8754
-1-
Ver.2008-07-14
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
Operating Voltage :2.7 to 5.25V
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
CMOS Technology
Package Outline :SSOP10, QFN20-M1
PIN CONFIGURATION
PACKAGE OUTLINE
NJU8754V
NJU8754KM1
QFN20-M1
VSS
VSS
NC
VDD
NC
NC
IN
COM
MUTEB
NC
VSS
VSS
NC
STBYB
NC
NC
OUTP
VDDO
OUTN
NC
15
6
10
11 15
16
20
VDD
IN
COM
MUTEB
STBYB
VSS
OUTP
VDDO
OUTN
VSS
1
2
3
4
5
10
9
8
7
6
SSOP10
NJU8754
- 2 - Ver.2008-07-14
BLOCK DIAGRAM
PIN DESCRIPTION
No.
SSOP10 QFN20-M1 SYMBOL I/O FUNCTION
1 19 VDD − Power supply : VDD=3.6V
2 2 IN I Signal input
3 3 COM − Analog common
4 4 MUTEB I
Mute control
Low : Mute ON High : Mute OFF
5 7 STBYB I
Standby control
Low : Standby ON High : Standby OFF
6, 10 9,10, 6,17 VSS − Power GND : VSS=0V
7 12 OUTN O Negative output
8 13 VDDO − Output power supply
9 14 OUTP O Positive output
− 1,5,6,8,
11,15,18,20 NC − Non connection
*The relations of ”VSS= 0V” and “VDD= VDDO” must be maintained.
*VSS(SSOP10:Terminal No.6,10, QFN20-M1:Terminal No.9,10,16,17) should be connected at a nearest point to
the IC.
*VDDO(SSOP10:Terminal No.8, QFN20-M1:Terminal No.13) should be connected at a nearest point to the IC.
*MUTEB(SSOP10, QFN20-M1:Terminal No.4) and STBY(SSOP10:Terminal No.5, QFN20-M1:Terminal No.7)
must be connected to VDD, when these terminals are not used.
Pulse
Width
Modulator
Short
Protection
VDD
Control Logic Low BATT
Protection
Soft Start
VSS
+
-
+
-
IN
COM
MUTEB STBYB
OUTP
VDDO
OUTN
NJU3555NJU8754
-3-
Ver.2008-07-14
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 STBYB terminal 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 terminals(OUTP and OUTN) are in high impedance.
(3) Mute
By setting the MUTEB terminal to “L”, the Mute function is enabled, and the output terminals(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 terminals(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
Note 1) 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.
NJU8754
- 4 - Ver.2008-07-14
ABSOLUTE MAXIMUM RATINGS
(Ta=25°C)
PARAMETER SYMBOL RATING UNIT
Supply Voltage VDD
VDDO
-0.3 to +5.5
-0.3 to +5.5
V
V
Input Voltage Vin -0.3 to VDD+0.3 V
Operating Temperature Topr -40 to +85 °C
Storage Temperature Tstg -40 to +125 °C
Power Dissipation PD 360 (SSOP10)
620 (QFN20-M1) mW
* : Mounted on two-layer board of based on the JEDEC.
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)) /θja
Pdmax: Maximum Power Dissipation, Tjmax: Junction Temperature = 125°C
Ta: Ambient Temperature, θja: Thermal Resistance of package(SSOP10) = 400°C/W
Power dissipation of the NJU8754 itself is calculated, as shown below.
Pd(W) = PO(W) X RO(Ω) / RL(Ω) + PdIC(W)
Pd: Power Dissipation, PO: Output Power, RO: Internal Resistance(output driver)
RL: Load Resistance, PdIC: Power of internal circuit
NJU3555NJU8754
-5-
Ver.2008-07-14
ELECTRICAL CHARACTERISTICS
(Ta=25°C, VDD=VDDO= 3.6V, VSS= 0V, Input Signal=1kHz,
Input Signal Level=200mVrms, Frequency Band=20Hz to 20kHz,
Load Impedance=8Ω, 2nd-order 34kHz LC Filter(Q=0.85))
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNIT Note
VDD,VDDO Supply Voltage VDD 2.7 3.6 5.25 V
Input Impedance ZIN IN terminal - 20 - kΩ
Voltage Gain AV - 23 - dB
Output Power Efficiency Eeff Output THD=10% 80 83 - % 4
VDD=VDDO=5.0V, Po=600mW 0.05 0.08
Output THD THD VDD=VDDO=3.6V, Po=300mW 0.07 0.1
%
VDD=VDDO=5.0V
Output THD=10% 1.2
Output Power Po VDD=VDDO=3.6V
Output THD=10% 0.6
W
S/N SN A weight 75 80 - dB
Operating Current (Standby) IST - - 1 µA
VDD=VDDO=5.0V
No Filter, No Load 4 6
Operating Current
(No signal input) IDD VDD=VDDO=3.6V
No Filter, No Load 2.5 5
mA
VIH MUTEB, STBYB terminals 0.7VDD - VDD V
Input Voltage VIL MUTEB, STBYB terminals 0 - 0.3VDD V
Input Leakage Current ILK MUTEB, STBYB terminals - - ±0.1 µA
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.
2nd-order LPF : fc=34kHz / Refer to “Typical Application Circuit”.
Filters : 22Hz HPF + 20kHz LPF(AES17)
(with the A-Weight filter for S/N and Dynamic-range tests)
Input Signal
THD
Measuring
Apparatus
Filter
20kHz
(AES17)
2nd-orde
r
LC LPF
NJU8754 Test Board Audio Analyzer
Figure 1. Output THD and S/N Test System
NJU8754
NJU8754
- 6 - Ver.2008-07-14
TYPICAL APPLICATION CIRCUIT
<LCR Filter Configuration
NJU8754
VDD(1)
VSS(10)
OUTP(9)
OUTN(7)
22
µ
H
8Ω Speaker
22
µ
H 1µF
VDDO
(
8
)
VSS(6)
0.1
µ
F 47µF
VDD
0.1µF 10µF
VDD
IN(2) IN
COM(3)
MUTEB(4)
STBYB(5)
2.2µF
10µF
1
µ
F
NJU8754
VDD(19)
VSS(16,17)
OUTP(14)
OUTN(12)
22
µ
H
8Ω Speaker
22
µ
H 1µF
VDDO
(
13
)
VSS(9,10)
0.1
µ
F 47µF
VDD
0.1µF 10µF
VDD
IN(2) IN
COM(3)
MUTEB(4)
STBYB(7)
2.2µF
10µF
1
µ
F
QFN20-M1
SSOP10
NJU3555NJU8754
-7-
Ver.2008-07-14
<LR Filter Configuration>
Using the LCR filter the power consumption is somewhat lower than using the LR filter power consumption
when no signal input. The THD+N is somewhat influenced by the LR filter more than the LCR filter. Please test the
circuit carefully to fit your application.
Note 6) De-coupling capacitors must be connected between each power supply terminal and GND.
The capacity value should be adjusted on the application circuit and the operation temperature. It may
malfunction if capacity value is small.
Note 7) 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.
Note 8) 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.
Note 9) The transition time for MUTEB and STBYB signals must be less than 100µs. Otherwise, a malfunction
may be occurred.
Note 10) (1) – (19) indicates terminal number.
NJU8754
VDD(1)
VSS(10)
OUTP(9)
OUTN(7)
33
µ
H
8Ω Speaker
VDDO
(
8
)
VSS(6)
0.1
µ
F 47µF
VDD
0.1µF 10µF
VDD
IN(2) IN
COM(3)
MUTEB(4)
STBYB(5)
2.2µF
10µF
NJU8754
VDD(19)
VSS(16,17)
OUTP(14)
OUTN(12)
33
µ
H
8Ω Speaker
VDDO
(
13
)
VSS(9,10)
0.1
µ
F 47µF
VDD
0.1µF 10µF
VDD
IN(2) IN
COM(3)
MUTEB(4)
STBYB(7)
2.2µF
10µF
QFN20-M1
SSOP10
NJU8754
- 8 - Ver.2008-07-14
[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.
