MAX9720 查看數據表（PDF） - Maxim Integrated

零件编号

产品描述 (功能)

生产厂家

MAX9720

50mW, DirectDrive, Stereo Headphone Amplifier with SmartSense and Shutdown

Maxim Integrated 

50mW, DirectDrive, Stereo Headphone

Amplifier with SmartSense and Shutdown

PIN

TSSOP

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

BUMP

UCSP

D2

C2

D1

C1

B1

A1

B2

A2

A3

B3

A4

B4

C4

D4

C3

D3

NAME

VDD

MODE1

C1P

PGND

C1N

PVSS

MODE2

ALERT

INL

TIME

INR

SGND

SVSS

OUTR

HPS

OUTL

Pin Description

FUNCTION

Positive Power Supply

Mode Select 1 Logic Input

Flying Capacitor Positive Terminal

Power Ground. Connect to SGND.

Flying Capacitor Negative Terminal

Charge-Pump Output

Mode Select 2 Logic Input

Open-Drain Interrupt Logic Output

Left-Channel Audio Input

Debouncing Timer Capacitor

Right-Channel Audio Input

Signal Ground. Connect to PGND.

Amplifier Negative Power Supply. Connect to PVSS.

Right-Channel Output

Headphone Sense Input

Left-Channel Output

Detailed Description

The MAX9720 fixed-gain, stereo headphone amplifier

includes Maxim’s patented DirectDrive architecture and

SmartSense. DirectDrive eliminates the large output-

coupling capacitors required by conventional single-

supply headphone amplifiers. SmartSense automatically

detects the presence of a short at either output. Under a

fault condition, the shorted output is automatically

disabled and the stereo input signal is automatically

mixed and routed to the remaining active channel. This

prevents damage to the amplifier and optimizes power

savings by eliminating battery drain into a shorted load.

The device consists of two 50mW Class AB headphone

amplifiers, an internal feedback network (MAX9720A:

fixed -1V/V gain, MAX9720B: fixed -1.41V/V gain), a

mono mixer/attenuator, undervoltage lockout (UVLO)/

shutdown control, SmartSense, a charge pump, and

comprehensive click-and-pop suppression circuitry

(see Functional Diagram). The charge pump inverts the

positive supply (VDD), creating a negative supply

(PVSS). The headphone amplifiers operate from these

bipolar supplies with their outputs biased about GND

(Figure 1). The amplifiers have almost twice the supply

range compared to other single-supply amplifiers,

nearly quadrupling the available output power. The

benefit of the GND bias is that the amplifier outputs do

not have a DC component (typically VDD/2). This elimi-

nates the large DC-blocking capacitors required with

conventional headphone amplifiers, conserving board

space, system cost, and improving frequency

response.

The noninvasive SmartSense feature of the MAX9720

detects a short on either output. The SmartSense routine

executes when the device is powered up or brought out

of shutdown (see the SmartSense section). If a fault is

detected, the shorted channel is shut down, the output

goes high impedance, and the stereo audio input is

mixed/attenuated and fed to the remaining active chan-

nel. The device also features an ALERT output that indi-

cates to a host µC that SmartSense has detected a

short-circuit condition on either amplifier output.

Forced stereo and forced mono modes can also be

selected through the two MODE_ inputs. In forced

operation mode, SmartSense is disabled and the

device operates as specified by the MODE_ inputs,

regardless of output load conditions. A fast low-power

shutdown mode is also selected through the MODE_

inputs (see the Mode_ Selection section).

The UVLO prevents operation from an insufficient

power supply and click-and-pop suppression, which

eliminates audible transients on startup and shutdown.

Additionally, the MAX9720 features thermal overload

protection and can withstand ±4kV ESD strikes on the

output.

10 ______________________________________________________________________________________

Share Link: