MC34708 datasheet(91/159 Pages) FREESCALE

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Analog Integrated Circuit Device Data



Freescale Semiconductor

MC34708

Functional Block Description

7.8.4.2

Accessory Identification

The MC34708 monitors both the ID pin and the VBUS pin. When an accessory attachment is detected, the accessory

identification state machine will enter Active mode to start the identification flow. The ID detection state machine will determine

what ID resistor is attached and the Power Supply Type Identification or PSTI circuit will determine what type of power supply is

connected. The 32 kHz crystal must be placed across the XTAL 1 and XTAL2 pins for the accessory identification to work.

An identification conclusion is made when the identification flow is finished. The corresponding bit in the USB Device Type/Status

register is set to indicate the device type, and the ATTACH bit in the USB Interrupt Status register is set to inform the baseband.

If the attached accessory can't be identified, the Unknown_Atta bit in the USB Interrupt Status register is set.

There are three types of accessories that the MC34708 will automatically detect.

1. Recognized and supported. The following accessories are identified and configured automatically: USB port, UART, Audio

Type 1 cable, TTY accessory, USB jig cables, and UART jig cables.

2. Recognized but not supported. The following accessories can be identified but are not supported by the MC34708 PMIC:

A/V cables, Phone-Powered Devices, Audio Type 2 cables, dedicated charger, USB charger, A/V charger, 5-wire type 1

and type 2 chargers. The PMIC will detect that a charger is attached, when the VBUS voltage transitions above the

setpoint, which is defaulted to 4.35 V. When above this threshold for longer than the debounce period (VBUSDB[1:0]), the

USBDET interrupt is generated and USBDETS is set to a one. When the VBUS input falls below the VBUSTL[2:0]

threshold, the USBDET interrupt is generated immediately without any debounce and the USBDETS bit is low. See

Table 89 and Table 90. The USBOVP interrupt will be triggered when an over-voltage on VBUS (>6.5 V typical) is

detected during a device attach. The over-voltage interrupt is debounce by SUP_OVP_DB[1:0] bits on Table 91.

VUSB ACTIVE MODE - DC

VUSB

Output Voltage VOUT

•VINMIN < VIN < VINMAX ILMIN < IL < ILMA

VNOM - 4%

3.3

VNOM + 4%

VUSBLOPP Load Regulation

• 0 < IL < ILMAX from DM / DP, For any VINMIN < VIN < VINMAX

1.0

mV/mA

VUSBLIPP

Line Regulation

•VINMIN < VIN < VINMAX, For any ILMIN < IL < ILMAX

VUSBSCTH Short-circuit Protection threshold

•VINMIN < VIN < VINMAX, Short-circuit VOUT to ground

IMAX+20%

tOFF-VUSB Turn-off Time

• Disable to 0.8 V, per USB OTG specification parameter

VA_SESS_VLD VIN = VINMIN, VINMAX IL = 0

1.3

sec

VUSB ACTIVE MODE - AC

VUSBPSRR PSRR - IL = 75% of ILMAX 20 Hz to 20 kHz

•VIN = VINMIN + 100 mV

VUSBNOISE Output Noise - VIN = VINMIN IL = 75% of ILMAX

• 100 Hz – 50 kHz

•> 50 kHz – 1.0 MHz

1.0

0.2

V/Hz

Table 88. VUSB Electrical Characteristics

Characteristics noted under conditions BP = 3.6 V, VBUS = 5.0 V, -40 C  TA  85 C, unless otherwise noted. Typical values

at BP = 3.6 V and TA = 25 °C under nominal conditions, unless otherwise noted.

Symbol

Characteristic

Min

Typ

Max

Unit

Notes

MC34708 数据表(PDF) 91 Page - Freescale Semiconductor, Inc

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