MP2624GL datasheet(23/45 Pages) MPS

23 / 45 page

MP2624 – 4.5A SW CHARGER W/ I2C CONTROL, NVDC POWER PATH, USB OTG

MP2624 Rev.1.05

www.MonolithicPower.com

4/9/2018

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

DM/DP USB Detection

The USB ports in personal computers are

convenient places for portable devices (PDs) to

draw current for charging batteries. If the portable

device is attached to a USB host of hub, then the

USB specification requires the portable device to

draw a limited current (100mA/500mA in USB2.0,

and 150mA/ 900mA in USB3.0). When the

device is attached to a charging port, it is allowed

to draw more than 1.5A.

The MP2624 features input source detection

compatible

with

the

Battery

Charging

Specification Revision 1.2 (BC1.2) to program

the input current limit during default mode. The

user can force DP/DM detection in the host mode

by writing 1 to REG07 Bit [7].

When the input source is first applied, the input

current limit begins with 100mA by default. If the

input source passes the input source qualification,

the MP2624 starts DP/DM detection. The DP/DM

detection circuit is shown in Figure 10.

The DP/DM detection has two steps:

1. Data Contact Detection (DCD)

2. Primary Detection.

DCD detection uses a current source to detect

when the data pins have made contact during an

attach event. The protocol for data contact detect

is as follows:



The power device (PD) detects VIN

asserted.



The PD turns on DP IDP_SRC and the DM

pull-down resistor for 40ms.



The PD waits for the DP line to be low.



The PD turns off IDP_SRC and the DM pull-

down resistor when the DP line is

detected as low or the 40ms timer is

expired.

DCD allows the PD to start primary detection as

soon as the data pins have made contact. Once

the data contact is detected, the MP2624 will

jump to the primary detection immediately. If the

data contact is not detected, the MP2624 will

jump automatically to the primary detection after

300ms from the beginning of the DCD.

Primary detection is used to distinguish between

the USB host (or SDP) and different types of

charging ports.

During primary detection, the PD turns on the

VDP_SRC on DP and the IDM_SINK on DM. If the

portable device is attached to a USB host, the

DM is low.

Figure 9 shows the USB detection flow chart.

To be compatible with the USB specification and

BC1.2, set the input current limit according to the

values listed in Table 2.

Table 2: Input Current Limit vs. USB Type

DP/DM

Detection

OTG

IIN_LMT

REG08 [7:6]

Floating

100mA

SDP

LOW

100mA

SDP

HIGH

500mA

DCP

1.8A

The USB detection runs as soon as the VIN is

detected and is independent of the charge

enable status. After the DP/DM detection is

complete, the MP2624 will set the input current

limit according to Table 2 and assert the USB

port type in REG08 Bit [7-6]. The host is able to

revise the input current limit as well according to

the USB port type asserted in the REG08 Bit

[7:6].

VDP_SRC

VLGC_HI

IDP_SRC

CHG_DET

VDAT_REF

IDM_SINK

RDM_DWN

Figure 10: DP/DM Detection Circuit

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