ISP1109 データシートの表示（PDF） - Philips Electronics

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ISP1109

Universal Serial Bus transceiver with carkit support

Philips Electronics 

Philips Semiconductors

ISP1109

USB transceiver with carkit support

The ID detector has a switch that can be used to ground pin ID. This switch is controlled

by bit ID_PULLDN of the Resistor Control register, and bits PH_ID_INT and PH_ID_ACK

of the Audio Control register. See Table 3.

Table 3: ID pull-down control

ID_PULLDN PH_ID_ACK PH_ID_INT

0

0

0

0

0

1

0

1

0

0

1

1

1

X

X

Switch between ID and GND

off

on for time tWint(ID) then off; bit PH_ID_INT

auto-clears to 0

wait for time tint(ID), turn on the switch for tWint(ID) then

off; bit PH_ID_ACK auto-clears to 0

not defined

on

The ID detector also has a switch that is connected between the ID_PU and VREF pins. If

the voltage on the ID pin is higher than the voltage on the VREF pin, the switch will be

turned off. Otherwise, the switch will remain on.

7.4 Pull-up and pull-down resistors

The DP pull-up resistor can be enabled or disabled (default enabled) using register

bit DP_PULLUP, if VBUS is above Vth(svc). The pull-up resistance on pin DP (RUP(DP)) must

be enabled, if VCC > Vth(ISET) and VBUS > Vth(svc).

To support DP Session Request Protocol (SRP), it is required that a B-device can perform

DP pulsing when VBUS is below the session end threshold (0.2 V to 0.8 V). If register

bit DP_SRP_EN is set, the DP pull-up resistor will be enabled irrespective of the status of

VBUS.

Table 4: DP pull-up resistor (RUP(DP)) control

Bit

VBUS > Vth(svc)

DP_SRP_EN DP_PULLUP

0

0

X

0

1

no

0

1

X

0

1

X

0

1

yes

1

X

X

Pin

VCC(I/O) HIGH

X

X

LOW

X

HIGH

X

RESET_N

X

X

X

LOW

HIGH

HIGH

DP pull-up resistor (SW1)

off

off

off

off

on

on

The pull-up resistor is context variable, as described in document ECN_27%_Resistor.

The value of the pull-up resistor depends on the condition of the USB bus:

• When the bus is idle, the value of the resistor is 900 Ω to 1575 Ω (SW2 = on).

• When the bus is transmitting or receiving, the value of the resistor is 1425 Ω to

3090 Ω (SW2 = off).

DP also implements a weak pull-up resistor (RweakUP(DP)) that is controlled by

bit DP_WKPU_EN of the Resistor Control register; see Figure 4. RweakUP(DP) will be

connected to the DP pin (SW3 = on), if bit DP_WKPU_EN = 1 and the voltage on VBUS is

greater than Vth(svc).

9397 750 13355

Product data sheet

Rev. 01 — 14 July 2005

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

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