Datasheet

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Low Distortion, 1.5 W Audio

Power Amplifier

Data Sheet

SSM2211

Rev. G Document Feedback

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FEATURES

1.5 W output

with THD + N < 1%

Differential bridge-tied load output

Single-supply operation: 2.7 V to 5.5 V

Functions down to 1.75 V

Wide bandwidth: 4 MHz

Highly stable phase margin: >80°

Low distortion: 0.2% THD + N at 1 W output

Excellent power supply rejection

APPLICATIONS

Portable computers

Personal wireless communicators

Hands-free telephones

Speaker phones

Intercoms

Musical toys and talking games

FUNCTIONAL BLOCK DIAGRAM

Figure 1.

GENERAL DESCRIPTION

The SSM2211

is a high performance audio amplifier that

delivers 1 W rms of low distortion audio power into a bridge-

connected 8 Ω speaker load (or 1.5 W rms into a 4 Ω load).

The SSM2211 operates over a wide temperature range and is

specified for single-supply voltages between 2.7 V and 5.5 V.

When operating from batteries, it continues to operate down to

1.75 V. This makes the SSM2211 the best choice for unregulated

applications, such as toys and games.

Featuring a 4 MHz bandwidth and distortion below 0.2% total

harmonic distortion plus noise (THD + N) at 1 W, superior

performance is delivered at higher power or lower speaker load

impedance than competitive units. Furthermore, when the

ambient temperature is at 25°C, THD + N < 1%, and V

= 5 V

on a 4-layer printed circuit board (PCB), the SSM2211 delivers

a 1.5 W output.

The low differential dc output voltage results in negligible

losses in the speaker winding and makes high value dc blocking

capacitors unnecessary. The battery life is extended by using

shutdown mode, which typically reduces quiescent current

drain to 100 nA.

The SSM2211 is designed to operate over the −40°C to +85°C

temperature range. The SSM2211 is available in 8-lead SOIC

(narrow body) and LFCSP (lead frame chip scale) surface-

mount packages. The advanced mechanical packaging of the

LFCSP models ensures lower chip temperature and enhanced

performance relative to standard packaging options.

Applications include personal portable computers, hands-free

telephones and transceivers, talking toys, intercom systems, and

other low voltage audio systems requiring 1 W output power.

Protected by U.S. Patent No. 5,519,576.

OUT

IN–

IN+

SHUTDOWN

BYPASS

OUT

V– (GND)

BIAS

00358-001

SSM2211

Summary of content (24 pages)

PAGE 1
Low Distortion, 1.5 W Audio Power Amplifier SSM2211 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM 1.5 W output with THD + N < 1% Differential bridge-tied load output Single-supply operation: 2.7 V to 5.5 V Functions down to 1.75 V Wide bandwidth: 4 MHz Highly stable phase margin: >80° Low distortion: 0.
PAGE 2
SSM2211 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Bridged Output vs. Single-Ended Output Configurations ... 16 Applications ....................................................................................... 1 Speaker Efficiency and Loudness ............................................. 16 Functional Block Diagram .............................................................. 1 Power Dissipation..........
PAGE 3
Data Sheet SSM2211 Changes to Start-Up Popping Noise Section ...............................17 Changes to Ordering Guide ...........................................................20 10/02—Rev. A to Rev. B Deleted 8-Lead PDIP ......................................................... Universal Updated Outline Dimensions ........................................................15 5/02—Rev. 0 to Rev. A Edits to General Description ...........................................................
PAGE 4
SSM2211 Data Sheet SPECIFICATIONS VDD = 5.0 V, TA = 25°C, RL = 8 Ω, CB = 0.1 µF, VCM = VDD/2, unless otherwise noted. Table 1.
PAGE 5
Data Sheet SSM2211 VDD = 2.7 V, TA = 25°C, RL = 8 Ω, CB = 0.1 µF, VCM = VDD/2, unless otherwise noted. Table 3. Parameter GENERAL CHARACTERISTICS Differential Output Offset Voltage Output Impedance SHUTDOWN CONTROL Input Voltage High Input Voltage Low POWER SUPPLY Supply Current Supply Current, Shutdown Mode AUDIO PERFORMANCE Total Harmonic Distortion Symbol Conditions VOOS ZOUT AVD = 2 VIH VIL ISY = <100 mA ISY = normal ISY ISD VOUTA = VOUTB = 1.
PAGE 6
SSM2211 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Absolute maximum ratings apply at TA = 25°C, unless otherwise noted. θJA is specified for the worst case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4.
PAGE 7
Data Sheet SSM2211 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS SHUTDOWN 1 BYPASS 2 SSM2211 IN+ 3 8 VOUTB 7 V– 6 V+ TOP VIEW (Not to Scale) IN– 4 5 VOUTA IN+ 3 IN– 4 00358-002 SHUTDOWN 1 TOP VIEW (Not to Scale) 7 V– 6 V+ 5 VOUTA Figure 3. 8-Lead LFCSP Pin Configuration (CP-8-13) Table 6. Pin Function Descriptions Mnemonic SHUTDOWN BYPASS IN+ IN− VOUTA V+ V− VOUTB EPAD SSM2211 NOTES 1. CONNECT THE EXPOSED PAD TO V−. Figure 2. 8-Lead SOIC_N Pin Configuration (R-8) Pin No.
PAGE 8
SSM2211 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 10 10 TA = 25°C VDD = 5V AVD = 2 (BTL) RL = 8Ω PL = 500mW TA = 25°C VDD = 5V AVD = 2 (BTL) RL = 8Ω PL = 1W CB = 0 CB = 0 1 THD + N (%) THD + N (%) 1 CB = 0.1µF CB = 1µF 0.1 CB = 0.1µF 0.01 20 100 1k 10k CB = 1µF 00358-007 00358-004 0.1 0.01 20k 20 100 1k FREQUENCY (Hz) FREQUENCY (Hz) Figure 4. THD + N vs. Frequency Figure 7. THD + N vs. Frequency 10k 20k 10k 20k 10k 20k 10 10 CB = 0 CB = 0 THD + N (%) 0.
PAGE 9
Data Sheet 10 SSM2211 10 TA = 25°C VDD = 5V AVD = 2 (BTL) RL = 8Ω FREQUENCY = 20Hz CB = 0.1µF TA = 25°C VDD = 3.3V AVD = 2 (BTL) RL = 8Ω PL = 350mW 1 CB = 0 THD + N (%) THD + N (%) 1 0.1 CB = 0.1µF 0.1 1 00358-013 0.01 2 20 FREQUENCY (Hz) Figure 10. THD + N vs. POUTPUT Figure 13. THD + N vs. Frequency 10k 20k 10k 20k CB = 0.1µF 1 THD + N (%) THD + N (%) CB = 1µF 0.1 00358-011 0.1 0.1 1 TA = 25°C VDD = 3.3V AVD = 10 (BTL) RL = 8Ω PL = 350mW 0.
PAGE 10
SSM2211 10 Data Sheet 10 TA = 25°C VDD = 3.3V AVD = 2 (BTL) RL = 8Ω FREQUENCY = 20Hz CB = 0.1µF 1 TA = 25°C VDD = 2.7V AVD = 2 (BTL) RL = 8Ω PL = 250mW CB = 0 THD + N (%) THD + N (%) 1 0.1 CB = 0.1µF 0.1 0.1 1 00358-019 0.01 20n 00358-016 CB = 1µF 0.01 2 20 POUTPUT (W) 10k 20k Figure 19. THD + N vs. Frequency 10 TA = 25°C VDD = 3.3V AVD = 2 (BTL) RL = 8Ω FREQUENCY = 1kHz CB = 0.1µF CB = 0 CB = 0.1µF 1 THD + N (%) THD + N (%) 1 CB = 1µF 0.1 0.1 0.1 1 0.
PAGE 11
Data Sheet 10 SSM2211 10 TA = 25°C VDD = 2.7V AVD = 2 (BTL) RL = 8Ω FREQUENCY = 20Hz 1 TA = 25°C VDD = 5V AVD = 10 SINGLE ENDED CB = 0.1µF CC = 1000µF THD + N (%) THD + N (%) 1 0.1 RL = 8Ω PO = 250mW 0.1 10 0.1 1 0.01 2 20 100 1k POUTPUT (W) FREQUENCY (Hz) Figure 22. THD + N vs. POUTPUT Figure 25. THD + N vs. Frequency 10k 20k 10k 20k 10k 20k 10 TA = 25°C VDD = 2.7V AVD = 2 (BTL) RL = 8Ω FREQUENCY = 1kHz TA = 25°C VDD = 3.3V AVD = 10 SINGLE ENDED CB = 0.
PAGE 12
SSM2211 4.0 VDD = 2.7V THD + N (%) 1 VDD = 3.3V VDD = 5V 1 1.0 8-LEAD SOIC 0.5 0 10 20 30 40 50 60 70 80 90 100 110 120 AMBIENT TEMPERATURE (°C) Figure 28. THD + N vs. POUTPUT Figure 31. Maximum Power Dissipation vs. Ambient Temperature 10k VDD = 2.7V TA = 25°C VDD = 5V 8k THD + N (%) VDD = 5V VDD = 3.3V 6k 4k 2k 1 0 2 00358-032 00358-029 0.1 0 1 2 3 5 4 POUTPUT (W) SHUTDOWN VOLTAGE AT PIN 1 (V) Figure 29. THD + N vs. POUTPUT Figure 32. Supply Current vs.
PAGE 13
Data Sheet SSM2211 25 1.6 VDD = 2.7V SAMPLE SIZE = 300 1.4 20 NUMBER OF UNITS 1.0 0.8 0.6 5V 00358-034 2.7V 8 12 16 20 24 28 32 36 40 44 0 –20 48 –15 –10 –5 0 5 10 15 20 LOAD RESISTANCE () OUTPUT OFFSET VOLTAGE (mV) Figure 34. POUTPUT vs. Load Resistance Figure 36. Output Offset Voltage Distribution 80 180 60 135 40 90 20 45 0 0 25 20 VDD = 3.
PAGE 14
SSM2211 Data Sheet 20 –50 VDD DD= =5V3.3V SAMPLE SIZE SIZE = = 300 300 SAMPLE TA = 25°C VDD = 5V ± 100mV CB = 15µF AVD = 2 –55 12 PSRR (dB) 8 –65 00358-038 4 0 –30 –20 –10 0 10 –70 30 20 20 OUTPUT OFFSET VOLTAGE (mV) VDD = 5V SAMPLE SIZE = 1,700 400 300 200 100 00358-039 NUMBER OF UNITS 500 7 8 9 10 11 12 13 1k Figure 40. PSRR vs. Frequency 600 6 100 FREQUENCY (Hz) Figure 38.
PAGE 15
Data Sheet SSM2211 THEORY OF OPERATION The SSM2211 is a low distortion speaker amplifier that can run from a 2.7 V to 5.5 V supply. It consists of a rail-to-rail input and a differential output that can be driven within 400 mV of either supply rail while supplying a sustained output current of 350 mA. The SSM2211 is unity-gain stable, requiring no external compensation capacitors, and can be configured for gains of up to 40 dB. Figure 41 shows the simplified schematic.
PAGE 16
SSM2211 Data Sheet APPLICATIONS INFORMATION RF driving this speaker with a bridged output, 1 W of power can be delivered. This power translates to a 12 dB increase in sound pressure level from the speaker. 5V CC AUDIO INPUT RI CS 6 4 – 5 SSM2211 3 + 1 8 – Driving a speaker differentially from a BTL offers another advantage in that it eliminates the need for an output coupling capacitor to the load.
PAGE 17
Data Sheet SSM2211 POWER DISSIPATION Another important advantage in using a BTL configuration is the fact that bridged-output amplifiers are more efficient than single-ended amplifiers in delivering power to a load. Efficiency is defined as the ratio of the power from the power supply to the power delivered to the load. PL PSY PDISS   RL  PL  PL (7) 1.
PAGE 18
SSM2211 Data Sheet 1.6 0.35 RL = 4 1.4 MAX POUT @ 1% THD (W) 0.25 0.20 0.15 RL = 8 0.10 RL = 16 0 0 0.1 0.2 0.3 RL = 4Ω 1.0 RL = 8Ω 0.8 0.6 RL = 16Ω 0.4 0.2 00358-045 0.05 1.2 0 0.4 1.5 2.5 2.0 Figure 45. Power Dissipation vs. Single-Ended Output Power with VDD = 5 V 2 VDD 2 π 2 RL 3.5 4.0 4.5 5.0 Figure 46. Maximum Output Power vs. VSY Shutdown Feature The maximum power dissipation for a single-ended output is PDISS , MAX  3.
PAGE 19
Data Sheet SSM2211 The input signal to the SSM2211 is also connected to the noninverting terminal of A2. R1, R2, and R3 set the threshold voltage at which the SSM2211 is to be taken out of shutdown mode. The diode, D1, half-wave rectifies the output of A2, discharging C1 to ground when an input signal greater than the set threshold voltage is detected. R4 controls the charge time of C1, which sets the time until the SSM2211 is put back into shutdown mode after the input signal is no longer detected.
PAGE 20
SSM2211 Data Sheet The final design step is to select the input capacitor. When adding an input capacitor, CC, to create a high-pass filter, the corner frequency must be far enough away for the design to meet the bandwidth criteria. For a first-order filter to achieve a pass-band response within 0.25 dB, the corner frequency must be at least 4.14× away from the pass-band frequency. Therefore, (4.14 × fHP) < 20 Hz. Using Equation 2, the minimum size of an input capacitor can be found.
PAGE 21
Data Sheet SSM2211 LFCSP PCB CONSIDERATIONS The LFCSP is a plastic encapsulated package with a copper lead frame substrate. The LFCSP is a leadless package with solder lands on the bottom surface of the package, instead of conventional formed perimeter leads. A key feature that allows the user to reach the quoted θJA performance is the exposed die attach paddle (DAP) on the bottom surface of the package. When soldered to the PCB, the DAP can provide efficient conduction of heat from the die to the PCB.
PAGE 22
SSM2211 Data Sheet OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 6.20 (0.2441) 5.80 (0.2284) 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.
PAGE 23
Data Sheet SSM2211 NOTES Rev.