ANALOG DEVICES SSM2304 Service Manual

2 W Filterless Class-D

FEATURES

Filterless Class-D amplifier with built-in output stage 2 W into 4 Ω and 1.4 W into 8 Ω at 5.0 V supply with <10% THD 85% efficiency at 5.0 V, 1.4 W into 8 Ω speaker Better than 98 dB SNR (signal-to-noise ratio) Available in 16-lead, 3 mm × 3 mm LFCSP Single-supply operation from 2.5 V to 5.0 V 20 nA ultralow shutdown current Short-circuit and thermal protection Pop-and-click suppression Built-in resistors reduce board component count Default fixed 18 dB gain and user-adjustable

APPLICATIONS

Notebooks and PCs Mobile phones MP3 players Portable gaming Portable electronics Educational toys

GENERAL DESCRIPTION

The SSM2304 is a fully integrated, high efficiency, Class-D stereo audio amplifier. It is designed to maximize performance for portable applications. The application circuit requires a minimum of external components and operates from a single 2.5 V to 5.0 V supply. It is capable of delivering 2 W of continuous output power with less than 10% THD + N driving a 4 Ω load from a 5.0 V supply.

Stereo Audio Amplifier

SSM2304

The SSM2304 features a high efficiency, low noise modulation scheme. It operates with 85% efficiency at 1.4 W into 8 Ω from a

5.0 V supply and has a signal-to-noise ratio (SNR) that is better than 98 dB. PDM modulation is used to provide lower EMIradiated emissions compared with other Class-D architectures.

The SSM2304 has a micropower shutdown mode with a typical shutdown current of 20 nA. Shutdown is enabled by applying a logic low to the

The architecture of the device allows it to achieve a very low level of pop and click. This minimizes voltage glitches at the output during turn-on and turn-off, thus reducing audible noise on activation and deactivation.

The fully differential input of the SSM2304 provides excellent rejection of common-mode noise on the input. Input coupling capacitors can be omitted if the dc input common-mode voltage is approximately V

The SSM2304 also has excellent rejection of power supply noise, including noise caused by GSM transmission bursts and RF rectification.

The SSM2304 has a preset gain of 18 dB, which can be reduced by using external resistors.

The SSM2304 is specified over the commercial temperature range (−40°C to +85°C). It has built-in thermal shutdown and output short-circuit protection. It is available in a 16-lead, 3 mm × 3 mm lead-frame chip scale package (LFCSP).

SD

pin.

/2.

DD

FUNCTIONAL BLOCK DIAGRAM

Rext

SSM2304

INR+

INR–

SD

INL+

INL–

1

RIGHT IN+

RIGHT IN–

SHUTDOWN

LEFT IN+

LEFT IN–

GAIN = 300kΩ/ (47kΩ + Rext)

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

22nF

1

22nF

1

22nF

1

22nF

1

INPUT CAPS ARE OPTIONAL I F INPUT DC COM MON-MODE VOLTAGE IS APPRO XIMATELY V

47kΩ

DD

300kΩ

/2.

10µF

BIAS

Figure 1.

VBATT

0.1µF

MODULATOR

INTERNAL

OSCILLAT OR

MODULATOR

2.5V TO 5. 0V

VDDVDD

FET

DRIVER

FET

DRIVER

GNDGND

OUTR+

OUTR–

OUTL+

OUTL–

06162-001

SSM2304

REVISION HISTORY

12/06—Revision 0: Initial Version

Rev. 0 | Page 2 of 20

SSM2304

SPECIFICATIONS

VDD = 5.0 V; TA = 25oC; RL = 4 Ω, 8 Ω; gain = 18 dB; unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

DEVICE CHARACTERISTICS

Output Power P

O

R R R R R R R R R R R

Efficiency η P

P

Total Harmonic Distortion + Noise THD + N PO = 2 W into 4 Ω each channel, f = 1 kHz, VDD = 5.0 V 0.2 %

P

Input Common-Mode Voltage Range V

CM

Common-Mode Rejection Ratio CMRR Channel Separation Average Switching Frequency f Differential Output Offset Voltage V

X

TAL K

SW

OOS

POWER SUPPLY

Supply Voltage Range V

DD

Power Supply Rejection Ratio PSRR VDD = 2.5 V to 5.0 V, 70 85 dB PSRR

Supply Current I

SY

V V Shutdown Current I

SD

GAIN Closed-Loop Gain Av Rext = 0 18 dB Differential Input Impedance Z

IN

SHUTDOWN CONTROL

Input Voltage High V Input Voltage Low V Turn-On Time t

Turn-Off Time t Output Impedance Z

IH

IL

WU

SD

OUT

NOISE PERFORMANCE

Output Voltage Noise e

n

Signal-to-Noise Ratio SNR P

RL = 4 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 5.0 V 1.8 W

= 8 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 5.0 V 1.4 W

L

= 4 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 3.6 V 0.9 W

L

= 8 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 3.6 V 0.615 W

L

= 4 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 2.5 V 0.35 W

L

= 8 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, VDD = 2.5 V 0.275 W

L

= 4 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 5.0 V 2.4 W

L

= 8 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 5.0 V 1.53 W

L

= 4 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 3.6 V 1.1 W

L

= 8 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 3.6 V 0.77 W

L

= 4 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 2.5 V 0.45 W

L

= 8 Ω, THD = 10%, f = 1 kHz, 20 kHz BW, VDD = 2.5 V 0.35 W

L

= 2 W, 4 Ω, VDD = 5.0 V 75 %

OUT

= 1.4 W, 8 Ω, VDD = 5.0 V 85 %

OUT

= 1 W into 8 Ω each channel, f = 1 kHz, VDD = 3.6 V 0.25 %

O

1.0 VDD − 1 V

GSMVCM

= 2.5 V ± 100 mV at 217 Hz 60 dB

PO = 100 mW , f = 1 kHz 78 dB

1.8 MHz

2.0 mV

Guaranteed from PSRR test 2.5 5.0 V

GSM

V

= 100 mV rms at 217 Hz, inputs ac GND,

RIPPLE

= 0.01 μF, input referred

C

IN

68 dB

VIN = 0 V, no load, VDD = 5.0 V 7.0 mA

= 0 V, no load, VDD = 3.6 V 6.5 mA

IN

= 0 V, no load, VDD = 2.5 V 5.2 mA

IN

SD

= GND

SD

= VDD

20 nA

47 kΩ

ISY ≥ 1 mA 1.2 V ISY ≤ 300 nA 0.5 V SD

rising edge from GND to V

SD

falling edge from VDD to GND

SD

= GND

DD

VDD = 3.6 V, f = 20 Hz to 20 kHz, inputs are ac grounded, A

= 2.0 W, RL = 4 Ω 102 dB

OUT

= 6 dB, RL = 4 Ω, A weighting

V

30 ms 5 μs >100 kΩ

22 μV

Rev. 0 | Page 3 of 20

SSM2304

ABSOLUTE MAXIMUM RATINGS

Absolute maximum ratings apply at 25°C, unless otherwise noted.

Table 2.

Parameter Rating

Supply Voltage 6 V Input Voltage V Common-Mode Input Voltage V ESD Susceptibility 4 kV Storage Temperature Range −65°C to +150°C Operating Temperature Range −40°C to +85°C Junction Temperature Range −65°C to +165°C Lead Temperature Range

(Soldering, 60 sec)

DD

300°C

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages.

Table 3. Thermal Resistance

Package Type θ

16-lead, 3 mm × 3 mm LFCSP 44 31.5 °C/W

θ

JA

Unit

JC

ESD CAUTION

Rev. 0 | Page 4 of 20

SSM2304

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

ND

VDD

GND

G

VDD

14

13

16

15

PIN 1 INDICATOR

1OUTL+

2OUTL–

SSM2304

3SD

TOP VIEW

(Not to Scale)

4INL+

5

6

NC

INL–

NC = NO CONNECT

Figure 2. SSM2304 LFCSP Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 OUTL+ Inverting Output for Left Channel. 2 OUTL− Noninverting Output for Left Channel. 3

SD

Shutdown Input. Active low digital input.

4 INL+ Noninverting Input for Left Channel. 5 INL− Inverting Input for Left Channel. 6 NC No Connect. 7 NC No Connect. 8 INR− Inverting Input for Right Channel. 9 INR+ Noninverting Input for Right Channel. 10 NC No Connect 11 OUTR− Noninverting Output for Right Channel. 12 OUTR+

Inverting Output for Right Channel. 13 GND Ground for Output Amplifiers. 14 VDD Power Supply for Output Amplifiers. 15 VDD Power Supply for Output Amplifiers. 16 GND Ground for Output Amplifiers.

12 OUTR+

11 OU TR–

10 NC

9INR+

8

7

NC

INR–

6162-002

Rev. 0 | Page 5 of 20

SSM2304

TYPICAL PERFORMANCE CHARACTERISTICS

100

10

RL = 4Ω, 33µH GAIN = 18dB

VDD = 2.5V

100

10

RL = 8Ω, 33µH GAIN = 6dB

VDD = 2.5V

1

VDD = 3.6V

THD + N (%)

0.01

0.001

0.1

0.00010.00001 10

0.001 0. 01 0.1 1

OUTPUT PO WER (W)

Figure 3. THD + N vs. Output Power into 4 Ω, A

100

RL = 8Ω, 33µH GAIN = 18dB

10

1

0.1

THD + N (%)

0.01

VDD = 3.6V

VDD = 2.5V

VDD = 5V

= 18 dB

V

VDD = 5V

1

VDD = 3.6V

0.1

THD + N (%)

0.01

0.001

06162-020

0.000010.0000001 10

0.001 0.1

OUTPUT PO WER (W)

Figure 6. THD + N vs. Output Power into 8 Ω, A

100

VDD = 5V R

= 8Ω, 33µH

L

GAIN = 6dB

10

1

1W

THD + N (%)

0.01

0.001

0.1

0.25W

0.5W

VDD = 5V

= 6 dB

V

06162-004

0.001

0.000001 0.00010.00001 10

Figure 4. THD + N vs. Output Power into 8 Ω, A

100

RL = 4Ω, 33µH GAIN = 6dB

10

1

THD + N (%)

0.1

0.01

0.000001 0.0001

0.0000001

0.00001 10

Figure 5. THD + N vs. Output Power into 4 Ω, A

0.001 0.01 0.1 1

OUTPUT PO WER (W)

VDD = 2.5V

VDD = 3.6V

VDD = 5V

0.01

0.001

OUTPUT PO WER (W)

0.1

= 18 dB

V

1

= 6 dB

V

06162-003

06162-021

Rev. 0 | Page 6 of 20

0.0001 20 20k

Figure 7. THD + N vs. Frequency, V

100

VDD = 3.6V R GAIN = 6dB

10

1

0.1

THD + N (%)

0.01

0.125W

0.001

0.0001 20 20k

Figure 8. THD + N vs. Frequency, V

100 1k 10k

FREQUENCY (Hz)

DD

= 8Ω, 33µH

L

0.5W

0.25W

100 1k 10k

FREQUENCY (Hz)

= 3.6 V, RL = 8 Ω, AV = 6 dB

DD

= 5 V, RL = 8 Ω, AV = 6 dB

06162-005

06162-006

ANALOG DEVICES SSM2304 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

FUNCTIONAL BLOCK DIAGRAM

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS