Title: HighPerformance Audio Amplifiers for Portable Applications
11
2High-Performance Audio Amplifiers for Portable
Applications
Kevin Hoskins Alvin Fok
Audio Product Line Applications
2
3Overview
- New Products
- New Technology
- Package Technology Overview
- Design Aids
4New Products
- LM4854
- LM4838
- LM4867
- LM4868
- LM4894
- LM4910
- LM4911
5New Technology
6Package Technology Overview
- Leaded Surface-Mount Packages
- SO / MSOP /
TSSOP - Leadless Leadframe Packages
- LD / LQ
- microSMD Packages
- IBP / ITL
7Design Aids
8LM4910 Boomer Description
- Output Capacitor-less Stereo 35mW headphone
amplifier
9LM4910 Boomer Schematic
10LM4910 Boomer Specifications
- Stereo 35mW output (VDD 3.3V RL 32W)
- 65 dB PSRR _at_ f 217Hz
- 0.1uA Shutdown Current
11LM4910 Boomer Advantages
- Eliminates output coupling capacitors
- Eliminates ½ VDD bypass capacitor
- Eliminates noises during device turn on/off
12LM4910 Boomer Packaging Solutions
- Available in SO and MSOP packaging
13Classical Stereo Headphone Amplifier Circuit
- Single-ended stereo headphones
- DC blocking output capacitors (Co) required
14Why LM4910 Boomer?
- For audio frequencies Co is large
- Tradeoff between low frequency response and
system cost (large and expensive Co)
Co ? 1 / (2pfRL)
15Eliminating the Output Capacitor
- DC quiescent current through the headphone driver
must be zero - Addition of third amplifier as a buffered
reference voltage - 6dB PSRR
-
AMPA
VDD
-
AMPC
AMPB
-
16Bandgap Reference Voltage
- A bandgap is used to create VREFERENCE
- VREFERENCE is independent of the LM4910s supply
voltage - 6dB PSRR problem eliminated (65dB PSRR _at_ 217Hz)
17Limitation of the Bandgap Reference Voltage
- VREFERENCE 1.58V
- Ideal for a supply range of 3.0V ? VDD ? 3.3V
- Aimed at PDA and other portable electronic
applications
Output Power _at_ VDD 3.3V (1 THDN)
EQUALS Output Power _at_ VDD 5.0V
(1 THDN)
18Limitation of the Bandgap Reference Voltage (cont)
5V
3.16V
1.58V
Audio signal
0V
19Limitation of the Bandgap Reference Voltage (cont)
20Limitation of the Bandgap Reference Voltage (cont)
- High output noise (45?V) mostly generated from
the bandgap reference - No Bypass Cap to filter the reference voltage
21Output Noise
- NoiseAMPA NoiseBANDGAP(1 RF/RI)
- NoiseAMPC NoiseBANDGAP
22Output Noise (cont)
- NoiseSPEAKER NoiseAMPA - NoiseAMPC
- NoiseSPEAKER NoiseBANDGAP(RF / RI)
RF
-
NoiseAMPA
AMPA
RI
NoiseBANDGAP
-
AMPC
NoiseAMPC
BANDGAP
NoiseBANDGAP
23Noise Reduction Resistor
24Noise Reduction Resistor (cont)
- NoiseVA NoiseAMPA(RL / (RL RSERIES))
- NoiseAMPA NoiseBANDGAP(1 RF / RI)
- NoiseAMPC NoiseBANDGAP
25Noise Reduction Resistor (cont)
- NoiseSPEAKER NoiseVA - NoiseAMPC
- NoiseSPEAKER NoiseBANDGAP(RF / RI)(RL / (RL
RSERIES))
26Noise Reduction Resistor (cont)
- Output noise across the speaker is reduced by the
factor (RL / (RL RSERIES))
27Noise Reduction Resistor (cont)
28Noise Reduction Resistor (cont)
- RSERIES limits the output power delivered to the
speaker - Output power is decreased by the factor of (RL /
(RL RSERIES)2) - RSERIES is an alternative way to reduce gain
29Noise Reduction Resistor (cont)
30Headphone Application Hints
- 2mW of headphone output power at the ear is
approaching the human threshold of pain - Many headphone applications incorporate an output
power limiting series resistor - Most new portable electronic music devices have
an output power rating
31Physical Connection
FLOATING JACK DO NOT CONNECT SLEEVE TO GROUND IN
YOUR SYSTEM
Headphone Jack
VoC
VoB
VoA
C
LM4910
Headphone Plug
32Physical Connection (cont)
- No problem connecting to external consumer audio
equipment under common GND condition when
using Headphone Jack as Line Out !!
33Physical Connection (cont)
- Even in the case where the headphone jacks
sleeve is grounded, the - LM4910s short circuit protection is activated
34LM4910 Boomer Short Circuit Protection
- Monitors the current of the amplifer (AMPC) that
drives the headphone jacks sleeve - If this current is greater than 500mA then AMPC
will immediately turn off - Protects the LM4910 as well as the external
equipment
35Output Capacitorless Power Dissipation
- Output Capacitor-less configuration has increased
power dissipation due to VREFERENCE amplifier
(AMPC) - Four times the maximum power dissipation of a
classical stereo headphone amplifier
36Power Dissipation Comparison
37LM4911 Boomer Description
- Stereo 25mW low noise amplifier with selectable
Capacitive Coupled (C-CUPL) or Output
Capacitor-less (OCL) output modes
38LM4911 Boomer Schematic(OCL Mode)
39LM4911 Boomer Schematic(C-CUPL Mode)
40LM4911 Boomer Specifications
- Mute mode allows fast turn-on (10ms)
- Less than 1mV of output voltage change when
toggling Mute Mode - Low noise (10 ?V)
- Stereo 25mW output (VDD 3.3V RL 32W)
41LM4911 Boomer Advantages
- Eliminates output coupling capacitors in OCL Mode
- Ultra low Click/Pop (1mV)
42LM4911 Boomer C-CUPL Mode
VoA
- Output coupling capacitors connected to VoA, VoB
- VoC is grounded
VoC
VoB
43LM4911 Boomer C-CUPL Mode (cont)
AMPC
VoC
- Grounding VoC deactivates AMPC
44LM4911 Boomer C-CUPL Mode (cont)
- To maintain 1mV output voltage change while
toggling SHUTDOWN mode, turn on time is 2S in
C-CUPL mode
45LM4911 Boomer OCL Mode
- VoA, VoB, VoC are at the same potential
- Headphones can be directly connected to amplifier
outputs - Similar to LM4910 operation
VoA
VoC
VoB
46LM4911 Boomer Mute Mode
- Allows for fast turn-on time (10mS typ) in
C-CUPL mode - Outputs are left at bias level
- Higher power consumption than SHUTDOWN mode
47LM4911 Boomer Mute Mode (cont)
- Switch closes during Mute Mode
VDD
VDD
-
AMPA
VDD
-
AMPC
48LM4911 Boomer Mute Mode (cont)
N / A Not Allowed
49LM4911 Boomer Packaging Solutions
- Available in MSOP packaging
50LM4894 Boomer Description
- Fully Differential 1W mono BTL amplifier
- Selectable Shutdown Mode (Low or High)
- No Input Coupling Caps Needed
- Very low Click/Pop
51LM4894 Boomer Schematic
52LM4894 Boomer Specifications
- High PSRR Vdd5V, input terminated 10? to GND
- 80dB (typ)
- Po at Vdd5V, THDN ? 1, RL 8?, f1kHz
- 1W (typ)
53LM4867 Description
- 2.1W per channel, 4W BTL
- Capless SE stereo headphone amp (165mW, 16W)
- Truly, actual Pop-free, click-free operation
- Turn-on, BTL-SE switching, return from shutdown
54LM4867 Schematic
55LM4867 Boomer Dual 2.1W Audio Power Amp
Stereo Headphone Mode
- LM4867 KEY FEATURES
- 2 input MUX with individual
- Gain Setting
- Pop-Click Elimination circuitry
- Minimal Externals -
- No Bootstraps, Snubbers
- No Output Coupling Caps
- for speaker or headphone use
56LM4867 Boomer Dual 2.1W Audio Power Amp
Stereo Headphone Mode
- LM4867 OUTPUT POWER
- LM4867LQ
- 2.4W _at_1.0 THD (Vcc5V, RL3ohm)
- 2.1W _at_1.0 THD (Vcc5V, RL4ohm)
- LM4867MT/MTE
- 1.9W _at_1.0 THD (Vcc5V, RL4ohm)
- 1.1W _at_1.0 THD (Vcc5V, RL8ohm)
- Stereo Headphone Mode
- 75mW _at_ 0.5 THD (Vcc5V, RL32ohm)
- Low-Current Shutdown Mode
- (ISD0.7uA), SDHigh
57LM4867 Boomer Physical Headphone Connection
FLOATING JACK DO NOT CONNECT SLEEVE TO GROUND IN
YOUR SYSTEM
OUT A OUT A - HP- IN OUT B - OUT B
T
R
SPEAKER HEADPHONE CONNECTIONS
LM4867
- No Output Coupling Capacitors Required for
Headphone Mode !! - System Cost Reduction
58LM4867 Boomer Mute Threshold
- Virtually eliminates Pops and Clicks when
toggling in and out of SHUTDOWN mode - Uses audio input signal monitoring
- Maintains muted condition until there is
sufficient audio input signal magnitude to mask
any remaining transient that may occur - Mute threshold 60mVRMS (typ)
- LM4868 is pin-for-pin compatible, its Mute
threshold is 25mVRMS (typ)
59LM4867 BoomerESD Protection Headphone Mode
- Out A drives the headphone jack sleeve during
headphone mode - Out A provides a VDD/2 reference point
- There is a direct connection from the IC pin to
outside world - The LM4867 provides the following protection
- 8kV Human body model
- 200V Machine Model
60LM4867 Applications Hints
- ESD protection for pin connected to headphone
jack sleeve is 8kV - For maximum ESD protection (15kV) an ESDAxxxL
dual transil - VDD 3V, use the ESDA5V3L
- VDD 5V, use the ESDA6V3L
- A Resistor (100W) from headphone sleeve to
ground - Minimizes 60Hz noise when computer/notebook is
shutdown and powered speakers are connected.
61ESDRecommended protection
HP-Jack Sleeve
- Connect the array directly to the HP- jacks
sleeve pin - In Lab survived 8kV surface1 and 15kV air2
discharge - Note 1 10 hits - ckt unpowered, 10 hits - ckt
powered - Note 2 5 hits - ckt unpowered, 5 hits - ckt
powered
-
AMP2A
VDD
62EMISuppression for non-grounded HP-jack sleeve
- Use capacitors and ferrite beads between
amplifier output and speaker and headphone jack
terminals - Provides suppression on the speaker terminals
- Provides suppression on the headphone jack
- For the LM4867, the capacitor and ferrite beads
can be used on the headphone sleeve connection
63LM4867 Advantages
- Advantages over traditional audio amplifier.
- Eliminates four capacitors
- Two 220mF coupling capacitors for headphones
- Two 1mF bypass capacitors
- Eliminates three resistors
- Two 220kW resistors that discharge the headphone
coupling capacitors - One 100kW pull-down resistor
64LM4867 Advantages, Cont.
- Glitch-free operation
- Output remains muted until input signal exceeds
60mVRMS magnitude 35mVRMS (min) to 85mVRMS
(max) - More efficient board area utilization
- Fewer external components
- Smaller TSSOP 20-pin vs. 24-pin
- Even smaller package 4mm x 5mm 24-pin LLP
65LM4867 Packaging Solutions
0.8mm
6.4mm
4mm
6.4mm
5mm
6.5mm
7.8mm
TSSOP-20
LLP-24
TSSOP-24
0.65mm Pitch
0.5mm Pitch
0.65mm Pitch
Traditional Solution
LM4867 High Performance Solution
66LM4867 Cost Analysis Vs. Traditional Amplifier
Solution
- Cost analysis.
- The LM4867 saves 0.70 per board
LM4867 Traditional Amp ESD
Protection (x1) 0.10 NA Pulldown Resistor
(x1) NA 0.01 HP Sleeve Resistor (x1)
0.01 NA SE Pulldown Resistors (x2)
NA 0.02 Output Coupling Caps (x2)
NA 0.60 Bypass Capacitor (x2)
NA 0.20 Total 0.11 0.83
67LM4854 Boomer Mono BTL Stereo Headphone
Amplifier
- Features
- Fast 0.1ms (typ) and 1.0ms (max) turn-on and
turn-off time - Capacitorless headphone operation eliminates
output coupling capacitors - Advanced click and pop suppression circuitry
- Low-power standby current is only 27mA (typ)
- Ultra-low micropower shutdown current is only
0.05mA (typ) - 2.4V to 5.5V operation
- Space-saving micro SMD package, exposed-DAP LLP,
and TSSOP - Thermal shutdown protection circuitry
68LM4854 Boomer Mono BTL Stereo Headphone
Amplifier
- Shutdown vs. Standby
- Shutdown disables the VDD/2 circuitry, all bias
circuitry, and mutes the amplifiers outputs - When power is first applied or shutdown is
deactivated, turn-on time is typically 120ms
tCBYPASS - Standby simply mutes the amplifier outputs
- During standby, all bias and VDD/2 circuitry
remain active - Activating or deactivating standby typically
takes 0.1ms - The fast standby time is the LM4854s key feature
- Shutdown current 0.05mA (typ)
- Standby current 27mA (typ)
69LM4854 Mono BTL Stereo Headphone Amplifier
- Key Specifications
- LLP BTL output power (RL 4W, THDN 1)
- VDD 3.0V 900mW (typ)
- VDD 5.0V 1.7W (typ)
- LLP BTL output power (RL 8W, THDN 1)
- VDD 3.0V 380mW (typ)
- VDD 5.0V 1.1W (typ)
- SE output power (RL 32W, THDN 1.0)
- VDD 3.0V 32mW (typ)
- VDD 5.0V 93mW (typ)
70LM4854 Mono BTL Stereo Headphone Amplifier
- Key Specifications (cont.)
- Micropower shutdown supply current
- VDD 3.0V 0.005µA (typ)
- VDD 5.0V 0.05µA (typ)
- Standby supply current
- VDD 3.0V 16µA (typ)
- VDD 5.0V 27µA (typ)
- PSRR (f 1kHz, 3.0V VDD 5.0V)
- BTL 60dB (typ)
- SE 66dB (typ)
71LM4854 Mono BTL Stereo Headphone Amplifier
72LM4854 Mono BTL Stereo Headphone Amplifier
- Applications
- PDAs
- Notebook computers
- Cellular phones
- Handheld portable electronic devices
73LM4838 Stereo BTL Headphone Amplifier
- Features
- Improved DC Volume Control
- Revised Volume Control curve, more natural
response - Click and pop suppression circuitry
- Stereo bridged or single-ended power amplifiers
- Selectable internal/external gain and bass boost
- Thermal shutdown protection circuitry
- System Beep Detect
74LM4838 Stereo BTL Headphone Amplifier
- Key Specifications
- BTL POUT (1 THDN)
- RL 3W (LQ MTE) 2.2W (typ)
- RL 4W (LQ MTE) 2.0W (typ)
- RL 8W (MT, MTE, LQ) 1.1W (typ)
- Single-ended POUT (1 THDN)
- RL 3W 85mW (typ)
- Shutdown current 0.7µA (typ)
75LM4838 Stereo BTL Headphone Amplifier
76LM4838 Stereo BTL Headphone Amplifier
- Applications
- Portable and Desktop Computers
- Multimedia Monitors
- Portable Radios
- PDAs
- Portable TVs
77NS Audio ProductSurface Mount Package Technology
6.4MM
4.9MM
10MM
9.7MM
3MM
10.1MM
TSSOP-28 MTE-1
MSOP-8 MM
SO16 M
0.65MM Pitch
0.65MM Pitch
1.27MM Pitch
6.4MM
5.8MM
4.9MM
6.5MM
4.8MM
3MM
SO8 M
MSOP-10 MM
TSSOP-20 MT,MTE
0.5MM Pitch
0.65MM Pitch
1.27MM Pitch
78micro-SMD
- Micro-SMD
- LM4872 IBP
- LM4877 IBP
- LM4890 IBP
79micro-SMD
- National leads in this package technology
- Highest audio quality and output power (1W) in
the smallest package available today - The Die is the Package
LM4872 IBP Actual Die Photo Total Area 2.58 mm2
1.97 mm
80Footprint Comparison
1.31 mm
1.97 mm
LM4872IBP 2.6 mm2 LM4877IBP LM4890IBP 1 W Boomer
LM4864MM 250mW Boomer 14.7 mm2
LM4871M 1 W Boomer 29.4 mm2
81PCB Layout Guidelines
- micro SMD
- Non-Solder Mask-Defined (NSMD) pads
- 11 size landing pad area vs micro SMD bump
diameter
82PCB Layout Guidelines
- micro SMD
- Solder paste stencil apertures must be laser-cut
83PCB Layout Guidelines
- micro SMD
- Electroplated NiAu finish on board must be less
than 0.5mm to avoid solder-joint embrittlement - See AN1112 for more information
- Available for LM4890, LM4872, LM4877
84PCB Layout Guidelines
- micro SMD
- LM4890 demo board layout
85NS Advanced Package Technology Leadframe CSP (
LLP)
0.8MM
4MM
5MM
LLP-24 LQ
0.5MM Pitch
86Lead-less Lead Frame (LLP)
- Higher Output Power
- Perfect for Audio Sub-system products
- Current Leadless Lead Frame (LQ and LD) Products
- LM4871 LD
- LM4863 LQ
- LM4873 LQ
- and more to come
87LM4871LD 4871 in LLP
- Pout up to 3.0W
- Package Size Reduction MSOP8 vs. LLP8 is 39
Please not that all numbers are preliminary and
still subject to significant changes
88PCB Layout Guidelines
- LLP (w/ exposed DAP)
- 11 size landing pad area vs LLP pin and DAP area
- Non-Solder Mask-Defined (NSMD) landing pads
- DAP area perforated with 12mil 13mil thermal
transfer via array on a 1.27mm pitch
89PCB Layout Guidelines
- LLP (w/ exposed DAP)
- Vias connect DAP to thermal mass/heatsink area
(bottom side or inter-layer - Thermal mass/heatsink area ?40x package area
- Even for the largest package (7mm x 7mm),
heatsink area is 45mm x 45mm - 0.05?m 0.127?m gold plating
90PCB Layout Guidelines
- LLP (w/ exposed DAP)
- Solder Stencil
- DAP stencil dimensions are 0.95 package DAP
dimensions - Pin stencil dimensions are 1-to-1, offset 0.1mm
away from DAP - For DAPs with any side larger than 5mm, split
stencil opening into two equal areas separated by
0.5mm - See AN1187 for more information
91PCB Layout Guidelines
- LLP (w/ exposed DAP)
- LM4871 demo board layout
92PCB Layout Guidelines
- General Guidelines
- Star grounding
- 90 crossing of traces between planes
- Separate digital and analog power and ground
- Locate high-speed digital lines far from analog
components and traces
9393