Rainbow Electronics MAX98500 User Manual

19-5189; Rev 0; 5/10

Boosted 2.2W Class D Amplifier

with Automatic Level Control

General Description

The MAX98500 is a high-efficiency, Class D audio ampli­fier that features an integrated boost converter to deliver
a constant output power over a wide range of battery
supply voltages.

The boost converter operates at 2MHz, requiring only a
small (2.2FH) external inductor and capacitor.

The automatic level control has a battery tracking func­tion that reduces the output swing as the supply voltage
drops, preventing collapse of battery voltage.

The amplifier has differential inputs and an internal fully
differential design. The MAX98500 also features three
gain settings (6dB, 15.5dB, and 20dB) that are select­able with a logic input.

The MAX98500 is available in a small, 0.5mm pitch
16-bump WLP package (2.1mm x 2.1mm). It is specified
over the extended -40NC to +85NC temperature range.

Features

S Boosted Class D Output

S

Integrated Automatic Level Control

S

Output Power

2.2W into 8I, 10% THD+N

1.7W into 8I, 1% THD+N

Wide 2.5V to 5.5V Supply Voltage Range

S

S

Undervoltage Lockout Protection

S

High Total Efficiency of 87%

S

High Step-Up Switching Frequency (2MHz)

S

Active Emission Limiting for Low EMI

MAX98500

Applications

Cell Phones

Smartphones

GPS Devices

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX98500EWE+

+Denotes a lead(Pb)-free/RoHS-compliant package.

-40NC to +85NC

16 WLP

Mobile Internet Devices

Active Speaker Accessories

Typical Application Circuit appears at end of data sheet.

Simplified Block Diagram

BATTERY

LXV

OUTPUT

STAGE

V

CCOUT

A2

A1

PVDD

B1

SPKP

C1

SPKN

SDBST

SDSPK

GAIN

RKNEE B3

INP D2

INN

BAT

B4 A3

D4

C3

B2

D3

CONTROL

DIFFERENTIAL

INPUT

C4 A4 D1, C2

AGND SPKPGNDBSTPGND

BOOST CONVERTER

MAX98500

GAIN

_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

Boosted 2.2W Class D Amplifier
with Automatic Level Control

ABSOLUTE MAXIMUM RATINGS

V

to AGND .........................................................-0.3V to +6V

BAT

V

to BSTPGND, AGND .................................-0.3V to +6V

CCOUT

PVDD to SPKPGND .................................................-0.3V to +6V

BSTPGND, SPKPGND to AGND ......................... -0.3V to +0.3V

GAIN to AGND ........................................-0.3V to (V

SDBST, SDSPK to AGND ...................................... -0.3V to V

BAT

+ 0.3V)

BAT

All Other Pins (excluding LX) to AGND ..................-0.3V to +6V

Current Into/Out of LX, V
Continuous Current Into/Out of SPK_, PVDD,

MAX98500

, BSTPGND ..................... Q3.9A

CCOUT

SPKPGND .................................................................. Q800mA

Continuous Input Current (all other pins) ........................ Q20mA

Duration of Short Circuit Between V

CCOUT

and BSTPGND ...................................................... Continuous

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

(V

= 3.6V, RL = J between SPKP and SPKN, AV = +6dB, CIN = 1FF, 20Hz to 22kHz AC measurement bandwidth, TA = T

BAT

T

, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)

MAX

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Power-Supply Rejection Ratio
(Note 3)

Quiescent Current

Combined Efficiency
Shutdown Current I
Turn-On Time t

BOOST CONVERTER

Battery Supply Voltage Range V
Soft-Start Interval t
Undervoltage Lockout UVLO V
Boost Converter Output Voltage V
Output Current Limit I
Input Current Limit I
nMOS Current Limit I
pMOS Turn-Off Current Limit 10 mA
Switching Frequency f
Efficiency
Startup Short-Circuit Time Converter latch off 50 ms
Thermal Shutdown 165

LX Leakage Current

PSRR

I

VBAT

I

PVDD

SHDN

ON

BAT

ON

VCCOUTILOAD

MAX

LIMIT

LX,MAX

T

= +25NC, V

A

TA = +25NC, SDSPK = SDBST = V
T

= +25NC, V

A

TA = +25NC, PVDD = 5.55V, SDSPK =
SDBST = V

E P

OUT

V

SDSPK

Time from power-on to full operation 10 12 ms

BAT

V

BAT

Startup, V

S

E 0.1A P I

= 0V or 5.5V,

V

LX

V

CCOUT

BAT

= 1.7W, f = 1kHz, Z

= V

SDBST

falling 2.1 2.2 2.3 V

= 0mA 5.45 5.5 5.65 V

R = 3.6V

CCOUT

P 0.75A

OUT

= 5.5V

Duration of SPK_ Short Circuit to PVDD or

SPKPGND .............................................................. Continuous

Duration of Short Circuit Between SPKP

and SPKN ..............................................................Continuous

Continuous Power Dissipation, Multilayer Board (T

WLP (derate 20.4mW/NC above +70NC)........................1.33W

θ

(Note 1).................................................................49NC/W

JA

= +70NC)

A

Junction Temperature .....................................................+150NC

Operating Temperature Range .......................... -40NC to +85NC

Storage Temperature Range ............................ -65NC to +150NC

Soldering Temperature (reflow) ......................................+260NC

= 2.5V to 5.5V

BAT

= 0V, SDBST = V

SDSPK

BAT

BAT

95 dB

3.05

0.09 0.15

1.7 2.7

= 8I + 68FH

SPK

= 0V, TA = +25NC

87 %

0.04 1.5

2.5 5.5 V

5.6 ms

1.5 A

= 0V 0.3 0.5 A

3.3 A

1.8 2.0 2.2 MHz
93 %

= +25NC

T

A

-40NC P T

P +85NC

A

-1.0 +0.1 +1.0

0.1

MIN

mA

FA

NC

FA

to

2 ______________________________________________________________________________________

Boosted 2.2W Class D Amplifier

with Automatic Level Control

ELECTRICAL CHARACTERISTICS (continued)

(V

= 3.6V, RL = J between SPKP and SPKN, AV = +6dB, CIN = 1FF, 20Hz to 22kHz AC measurement bandwidth, TA = T

BAT

T

, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)

MAX

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SPEAKER AMPLIFIER

Output Offset Voltage V

Click-and-Pop Level K

Output Power (Note 5) P

Total Harmonic Distortion Plus
Noise

Output Switching Frequency 300 kHz

Gain A

Output Current Limit 2 A
Efficiency
Output Noise A-weighted 43

Input Resistance R

Common-Mode Rejection Ratio CMRR f = 1kHz 60 dB
Bias Voltage V

ALC

Attack Time 20
Release Time 1.6 s/dB
Maximum Attenuation 8 dB
Attenuation Resolution 0.5 dB

Knee Voltage V

OUT

THD+N

BIAS

KNEE

TA = +25NC

OS

Peak voltage, TA =
+25NC, A-weighted, 32
samples per second,

CP

Z

= 8I + 68FH,

SPK

(Notes 3, 4)

Z

= 8I + 68FH

SPK

f = 1kHz, P
Z

= 8I + 68FH

SPK

GAIN = AGND 5.5 6 6.5

V

GAIN = V

E P

IN

= 1.7W, f = 1kHz, Z

OUT

SDBST = SDSPK =
V

BAT

V

SDBST

TA = +25NC

= 850mW, TA = +25NC,

OUT

BAT

= V

SDSPK

Into shutdown -56

Out of shutdown -56

THD+N P 1%
THD+N P 10%

= 8I + 68FH

SPK

AV = 6dB
(GAIN = AGND)

= 15.5dB

A

V

(GAIN =
unconnected)

A

= 20dB

V

= 0V

(GAIN = V

All gain settings 110

R

= 154kI

KNEE

= 40.5kI

R

KNEE

R

= 13kI

KNEE

BAT

)

19.5 20 20.5

36 54 72

12 18 26

6.5 11 16

1.3 1.4 1.5 V

2.19 2.3 2.42

3.14 3.3 3.47

3.71 3.9 4.10

1 3 mV

1.7

2.2

0.05 %

92 %

MIN

dBV

W

dBGAIN = unconnected 15 15.5 16

FV

RMS

kI

Fs/dB

V

MAX98500

to

_______________________________________________________________________________________ 3

Boosted 2.2W Class D Amplifier
with Automatic Level Control

ELECTRICAL CHARACTERISTICS (continued)

(V

= 3.6V, RL = J between SPKP and SPKN, AV = +6dB, CIN = 1FF, 20Hz to 22kHz AC measurement bandwidth, TA = T

BAT

T

, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)

MAX

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

= 3.25V 43.2

V

KNEE

V

= 3.35V 37.4

KNEE

= 3.45V 32.4

V

KNEE

= 3.55V 27.4

V

KNEE

= 3.65V 23.2

V

KNEE

= 3.75V 18.7

V

KNEE

= 3.85V 15.0

V

KNEE

Knee Resistor R

KNEE

MAX98500

DIGITAL INPUTS (SDBST, SDSPK)

Input Voltage High V
Input Voltage Low V
Input Capacitance C
Input Leakage Current I

Note 2: 100% production tested at T
Note 3: Amplifier inputs are AC-coupled to AGND.
Note 4: Mode transitions are controlled by SDSPK.

IN

= +25NC. Specifications over temperature limits are guaranteed by design.

A

iH

IL

IN

TA = +25NC,
A

= 15.5dB

V

TA = +25NC

1.4 V

0.4 V

10 pF

-1.0 +1.0

MIN

kI

FA

to

4 ______________________________________________________________________________________

Boosted 2.2W Class D Amplifier

with Automatic Level Control

Typical Operating Characteristics

(V

= 3.6V, RL = ∞ between SPKP and SPKN, AV = +15.5dB, RKNEE = V

BAT

otherwise noted.)

General

BATTERY CURRENT

vs. BATTERY VOLTAGE

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

BATTERY CURRENT (mA)

1.0

0.5

0

2.5 5.5

INPUTS AC-COUPLED TO AGND
SDSPK = SDBST = V

BATTERY VOLTAGE (V)

BAT

MAX98500 toc01

5.04.54.03.53.0

, 20Hz to 22kHz AC measurement bandwidth, unless

BAT

BATTERY CURRENT

vs. BATTERY VOLTAGE

140

120

100

BATTERY CURRENT (µA)

80

60

2.5 5.5

INPUTS AC-COUPLED TO AGND
SDSPK = GND, SDBST = V

BATTERY VOLTAGE (V)

BAT

MAX98500 toc02

5.04.54.03.53.0

MAX98500

BATTERY CURRENT

vs. BATTERY VOLTAGE

10

INPUTS AC-COUPLED TO AGND

9

SDSPK = V

8

7

6

5

4

3

BATTERY CURRENT (µA)

2

1

0

2.5 5.5

, SDBST = AGND

BAT

BATTERY VOLTAGE (V)

MAX98500 toc03

5.04.54.03.53.0

EFFICIENCY vs. OUTPUT POWER

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

0 2.5

V

BAT

V

= 3.0V

BAT

Z

LOAD

fIN = 1kHz

P

(W)

OUT

OV

OV

OV

V

= 4.2V

BAT

= 3.6V

= 8I + 68µH

2.01.51.00.5

TURN-ON RESPONSE

2ms/div

MAX98500 toc05

MAX98500 toc04

SDBST
2V/div

V

CCOUT

2V/div

SPKR
OUTPUT
1V/div

_______________________________________________________________________________________ 5