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LM4651 & LM4652 Overture Audio Power Amplifier 170W Class D Audio Power Amplifier Solution
August 2000
LM4651 & LM4652 Overture ™ Audio Power Amplifier
170W Class D Audio Power Amplifier Solution
General Description
The IC combination of the LM4651 driver and the LM4652
power MOSFET provides a high efficiency, Class D sub-
woofer amplifier solution.
The LM4651 is a fully integrated conventional pulse width
modulator driver IC. The IC contains short circuit, under
voltage, over modulation, and thermal shut down protection
circuitry. It contains a standby function, which shuts down
the pulse width modulation and minimizes supply current.
The LM4652 is a fully integrated H-bridge power MOSFET
IC in a TO-220 power package. Together, these two IC’s
form a simple, compact high power audio amplifier solution
complete with protection normally seen only in Class AB
amplifiers. Few external components and minimal traces
between the IC’s keep the PCB area small and aids in EMI
control.
The near rail-to-rail switching amplifier substantially in-
creases the efficiency compared to Class AB amplifiers. This
high efficiency solution significantly reduces the heat sink
size compared to a Class AB IC of the same power level.
This two-chip solution is optimum for powered subwoofers
and self powered speakers.
Key Specifications
n Output power into 4
with < 10% THD.
170W (Typ)
n THD at 10W, 4 W , 10 − 500Hz.
< 0.3% THD (Typ)
n Maximum efficiency at 125W
85% (Typ)
n Standby attenuation.
> 100dB (Min)
Features
n Conventional pulse width modulation.
n Externally controllable switching frequency.
n 50kHZ to 200kHz switching frequency range.
n Integrated error amp and feedback amp.
n Turn−on soft start and under voltage lockout.
n Over modulation protection (soft clipping).
n Short circuit current limiting and thermal shutdown
protection.
n 15 Lead TO−220 isolated package.
n Self checking protection diagnostic.
Applications
n Powered subwoofers for home theater and PC’s
n Car booster amplifier
n Self-powered speakers
Connection Diagrams
LM4651 Plastic Package
LM4652 Plastic Package (Note 8)
DS101277-72
DS101277-73
Isolated TO-220 Package
Order Number LM4652TF
See NS Package Number TF15B
or
Non-Isolated TO-220 Package
Order Number LM4652TA
See NS Package Number TA15A
Top View
Order Number LM4651N
See NS Package Number N28B
Overture ® is a registered trademark of National Semiconductor Corporation.
© 2001 National Semiconductor Corporation
DS101277
www.national.com
W
29277004.002.png
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
Operating Ratings (Notes 1, 2)
Temperature Range
−40˚C
£
T A
£
+85˚C
Supply Voltage |V + |+|V − |
22V to 44V
± 22V
Thermal Resistance
LM4651 N Package
q JA
Output Current (LM4652)
10A
Power Dissipation (LM4651) (Note 3)
1.5W
52˚C/W
Power Dissipation (LM4652) (Note 3)
32W
q JC
22˚C/W
ESD Susceptibility (LM4651) (Note 4)
2000V
LM4652 (pins 2,6,10,11)
500V
LM4652 TF, TO−220 Package
q JA
ESD Susceptibility (LM4651) (Note 5)
200V
43˚C/W
LM4652 (pins 2,6,10,11)
100V
q JC
2.0˚C/W
Junction Temperature (Note 6)
150˚C
Soldering Information
N, TA and TF Package (10 seconds)
260˚C
LM4652 T, TO−220 Package
q JA
37˚C/W
Storage Temperature
−40˚C to + 150˚C
q
JC
1.0˚C/W
System Electrical Characteristics for LM4651 and LM4652 (Notes 1, 2)
The following specifications apply for +V CC = +20V, −V EE = −20V, f SW = 125kHz, f IN = 100Hz, R L =4 W , unless otherwise
specified. Typicals apply for T A = 25˚C. For specific circuit values, refer to Figure 1 (Typical Audio Application Circuit).
Symbol
Parameter
Conditions
LM4651 & LM4652
Typical
Units
I CQ
Total Quiescent Power Supply
Current
V CIN = 0V, L O = 0mA, |I VCC+ |+|I VEE− |
R DLY =0
237
124
mA
mA
W
I STBY
Standby Current
V PIN 13 = 5V, Stby: On
17
mA
A M
Standby Attenuation
V PIN 13 = 5V, Stby: On
> 115
dB
R L =4
W
, 1% THD
125
W
R L =4 W , 10% THD
155
W
P O
Output Power (Continuous Average)
R L =8
W
, 1% THD
75
W
R L =8
W
, 10% THD
90
W
f SW = 75kHz, R L =4
W
, 1% THD
135
W
f SW = 75kHz, R L =4
W
, 10% THD
170
W
h
Efficiency at P O =5W
P O = 5W, R DLY =5k
W
55
%
h
Efficiency
(LM4651 & LM4652)
P O = 125W, THD = 1%
85
%
Power Dissipation
(LM4651 + LM4652)
P O = 125W, THD = 1% (max)
22
W
Pd
f SW = 75kHz, P O = 135W,
THD = 1% (max)
22
W
THD+N
Total Harmonic Distortion Plus Noise
10W, 10Hz
£
f IN
£
500Hz, A V =18dB
0.3
%
10Hz
£
BW
£
80kHz
e OUT
Output Noise
A Weighted, no signal, R L =4 W
550
µV
SNR
Signal-to-Noise Ratio
A-Wtg, P out = 125W, R L 4
W
92
dB
22kHz BW, P out = 125W, R L 4
W
89
dB
V OS
Output Offset Voltage
V IN = 0V, I O = 0mA, R OFFSET =0
W
0.7
V
PSRR
Power Supply Rejection Ratio
R L =4
W
, 10Hz
£
BW
£
30kHz
37
dB
+V CC AC
=−V EE AC
=1V RMS ,f AC = 120Hz
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2
W
R DLY = 10k
29277004.003.png
Electrical Characteristics for LM4651 (Notes 1, 2, 7)
The following specifications apply for +V CC = +20V, −V EE = −20V, f SW = 125kHz, unless otherwise specified. Limits apply for
T A = 25˚C. For specific circuit values, refer to Figure 1 (Typical Audio Application Circuit).
Symbol
Parameter
Conditions
LM4651
Min
Typical
Max
Units
I CQ
Total Quiescent Current
LM4652 not connected, I O = 0mA,
|I VCC+ |+|I VEE− |, R DLY =0
W
15
36
45
mA
Standby
V IL
Standby Low Input Voltage
Not in Standby Mode
0.8
V
V IH
Standby High Input Voltage
In Standby Mode
2.5
2.0
V
f SW
Switching Frequency Range
R OSC = 15k W
65
kHz
R OSC =0
W
200
kHz
f SWerror
50% Duty Cycle Error
R OSC =4k
W
,f SW = 125kHz
1
3
%
T dead
Dead Time
R DLY =0
W
27
ns
T OverMod
Over Modulation Protection Time
Pulse Width Measured at 50%
310
ns
Electrical Characteristics for LM4652 (Notes 1, 2, 7)
The following specifications apply for +V CC = +20V, −V EE = −20V, unless otherwise specified. Limits apply for T A = 25˚C. For
specific circuit values, refer to Figure 1 (Typical Audio Application Circuit).
Symbol
Parameter
Conditions
LM4652
Min
Typical
Max
Units
V (BR) DSS
Drain−to−Source Breakdown
Voltage
VGS = 0
55
V
I DSS
Drain−to−Source Leakage Current VDS = 44V DC , VGS = 0V
1.0
mA
VGS th
Gate Threshold Voltage
VDS = VGS, ID = 1mA DC
0.85
V
R DS(ON)
Static Drain−to−Source On
Resistance
VGS=6V DC ,ID=6A DC
200
300
m
W
t r
Rise Time
VGD=6V DC , VDS = 40V DC ,R GATE
=0
W
25
ns
t f
Fall Time
VGD=6V DC , VDS = 40V DC ,R GATE
=0
W
26
ns
I D
Maximum Saturation Drain
Current
VGS=6V DC , VDS = 10V DC
8
10
A DC
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given, however, the typical value is a good indication of device performance.
Note 2: All voltages are measured with respect to the GND pin unless otherwise specified.
Note 3: For operating at case temperatures above 25˚C, the LM4651 must be de−rated based on a 150˚C maximum junction temperature and a thermal resistance
of
q JA = 62 ˚C/W (junction to ambient), while the LM4652 must be de−rated based on a 150˚C maximum junction temperature and a thermal resistance of
q JC =
2.0 ˚C/W (junction to case) for the isolated package (TF) or a thermal resistance of
q
JC = 1.0˚C/W (junction to case) for the non-isolated package (T).
Note 4: Human body model, 100 pF discharged through a 1.5 k
W
resistor.
Note 5: Machine Model, 220pF-240pF discharge through all pins.
Note 6: The operating junction temperature maximum, T jmax is 150˚C.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: The LM4652TA package TA15A is a non-isolated package, setting the tab of the device and the heat sink at −V potential when the LM4652 is directly
mounted to the heat sink using only thermal compound. If a mica washer is used in addition to thermal compound,
q
CS (case to sink) is increased, but the heat sink
will be isolated from −V.
3
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29277004.004.png
Electrical Characteristics for LM4652 (Notes 1, 2, 7) (Continued)
DS101277-68
FIGURE 1. Typical Application Circuit and Test Circuit
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LM4651 Pin Descriptions
Pin No.
Symbol
Description
1
OUT 1
The reference pin of the power MOSFET output to the gate drive circuitry.
2,27
BS 1 ,BS 2
The bootstrap pin provides extra bias to drive the upper gates, HG 1 ,HG 2 .
3
HG 1
High−Gate #1 is the gate drive to a top side MOSFET in the H-Bridge.
4
HG 2
High−Gate # 2 is the gate drive to a top side MOSFET in the H-Bridge.
5,15
GND
The ground pin for all analog circuitry.
6
+6V BYP
The internally regulated positive voltage output for analog circuitry. This pin is available
for internal regulator bypassing only.
7
+V CC
The positive supply input for the IC.
8
−6V BYP
The internally regulated negative voltage output for analog circuitry. This pin is available
for internal regulator bypassing only.
9
F BK V O
The feedback instrumentation amplifier output pin.
10
E RR I N
The error amplifier inverting input pin. The input audio signal and the feedback signal are
summed at this input pin.
11
E RR V O
The error amplifier output pin.
12
TSD
The thermal shut down input pin for the thermal shut down output of the LM4652.
13
STBY
Standby function input pin. This pin is CMOS compatible.
14
FBK 1
The feedback instrumentation amplifier pin. This must be connected to the feedback filter
from V O1 (pin 15 on the LM4652 ).
16
OSC
The switching frequency oscillation pin. Adjusting the resistor from 15.5k
W
to 0
W
changes the switching frequency from 75kHz to 225kHz.
17
Delay
The dead time setting pin.
18
SCKT
Short circuit setting pin. Minimum setting is 10A.
19
FBK 2
The feedback instrumentation amplifier pin. This must be connected to the feedback filter
from V O2 (pin 7 on the LM4652 ).
20,21
−V DDBYP
The regulator output for digital blocks. This pin is for bypassing only.
22,23
−V EE
The negative voltage supply pin for the IC.
24
START
The start up capacitor input pin. This capacitor adjusts the start up time of the diagnostic
sequence for the modulator. Refer to Start up Sequence and Timing in the
Application Information section.
25
LG 1
Low−Gate # 1 is the gate drive to a bottom side MOSFET in the H-Bridge.
26
LG 2
Low−Gate # 2 is the gate drive to a bottom side MOSFET in the H-Bridge.
28
OUT 2
The reference pin of the power MOSFET output to the gate drive circuitry.
5
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