DEVICE PLUG-IN

ADC = 0000?

START

REFER TO

DEVICE ID INDEX

SWITCH to 2.2k:

PULL-UP

ADC = 0000?

EAR JACK

DETECTED

ADC = 0000?

SWITCH to 620:

PULL-UP

YES

YES

YES

NO

NO

USB OTG

DETECTED

RETURN

ADC = 1011?

NO

USB DETECTION

DCPORT = 1?

CHPORT = 1?

DEDICATED

CHARGER

DETECTED

USB HOST/HUB

CHARGER

DETECTED

YES

YES

NO

NO

YES

ID DETECTION

(200k: PULL-UP)

NO

ADC = 0010?

PRODUCTION

TEST MODE

(USB)

NO

ADC = 0100?

PRODUCTION

TEST MODE

(UART)

YES

YES

NO

LP8727

www.ti.com

SNVS898A – OCTOBER 2012 – REVISED MAY 2013

Figure 4. Device Identification Diagram

ID DETECTION

When the external device is connected to Micro/Mini USB connector, the LP8727 reads the voltage of ID pin

using an ADC while the ID pin is pulled up to the output of ID DETECTION LDO (typ. 2.3V) through the internal

200 k

Ω resistor. If ADC value code is 4’h0000, the LP8727 will change the pullup resistor from 200 kΩ to 2.2 kΩ

and eventually to 620

Ω step-by-step for detecting microphone and USB OTG. In case that the first ADC reading

gives 4’h1011, then the LP8727 will start USB detection according to USB Battery Charging Specification

Revision 1.1.

Table 1. Device Indentification Index

ID RESISTOR

ADC VALUE

ADC VOLTAGE

D+ CONDITION

D

−CONDITION

VBUS [V]

FUNCTION

[k

Ω]

DETECTION VALUES with 200 k

Ω PULL-UP RESISTOR

1011

100%

OPEN

15 k

Ω to GND

15 k

Ω to GND

5

USB Cable

1011

100%

OPEN

Shorted to D

−

Shorted to D+

5.6

TA Charger

1010

81.90%

910

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Copyright © 2012–2013, Texas Instruments Incorporated

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