JDP2S01T Datasheet, PDF (47/150 Pages) Toshiba Semiconductor – UHF~VHF Band RF Attenuator Applications

Philips Semiconductors
ISP1362
Single-chip USB OTG controller
12.8.1 Using internal OC detection circuit
An application using the internal OC detection circuit and internal 15 kΩ pull-down
resistors is shown in Figure 23, where DMn denotes either OTG_DM1 or H_DM2,
while DPn denotes either OTG_DP1 or H_DP2. In this example, the HC Driver must
set both AnalogOCEnable and ConnectPullDown_DS1 (bit 10 and bit 12 of the
HcHardwareConfiguration register, respectively) to logic 1.
When H_OCn detects an overcurrent status on a downstream port, H_PSWn will
output HIGH to turn off the +5 V power supply to the downstream port V_BUS. When
there is no such detection, H_PSWn will output LOW to turn on the +5 V power
supply to the downstream port V_BUS.
In general applications, you can use a P-channel MOSFET as the power switch for
V_BUS. Connect the +5 V power supply to the drain pole of the P-channel MOSFET,
V_BUS to the source pole, and H_PSWn to the gate pole. This voltage drop (∆V) across
the drain and source poles can be called the overcurrent trip voltage. For the internal
overcurrent detection circuit, a voltage comparator has been designed-in, with a
nominal voltage threshold of 75 mV. Therefore, when the overcurrent trip voltage (∆V)
exceeds the voltage threshold, H_PSWn will output a HIGH level to turn off the
P-channel MOSFET. If the P-channel MOSFET has R_DSon of 150 mΩ, the overcurrent
threshold will be 500 mA. The selection of a P-channel MOSFET with a different
R_DSon will result in a different overcurrent threshold.
C41(1)
P_channel
MOSFET
FB2
drain
gate
source
C17
0.1 µF
VBUS ¹
DM ²
DP ³
GND ⁴
chassis ⁵
chassis ⁶
004aaa148
DGND
DGND
DGND
(1) 100 µF for the host port or 4.7 µF for the OTG port.
Fig 23. Using internal OC detection circuit.
VDD_5V
C18
0.1 µF
PSU_5V
R31
10 kΩ
H_PSWn
H_OCn
12.8.2 Using external OC detection circuit
When V_CC (pin 56) is connected to the +3.3 V power supply instead of the +5 V
power supply, the internal OC detection circuit cannot be used. An external
OC detection circuit must be used instead. Nevertheless, regardless of V_CC
connection, an external OC detection circuit can be used from time to time. To use an
9397 750 12337
Product data
Rev. 03 — 06 January 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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