RT7205AL datasheet(6/36 Pages) RICHTEK

6 / 36 page

RT7205A

DS7205A-00

February 2018

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Figure 1. CV and CC Loops

Interface of D+ and D-

The D+ and D- pins are used for BC1.2 compliance or for

communication with other proprietary protocols. The D+

and D- pins, connected to the MCU via an ADC, can be

reprogrammed for other purposes since they can be used

as an analog/digital input or output.

Figure 2. External Temperature Sensing

DOL

IBIAS_RT

MCU

RNTC

RT BIAS

10-bit ADC

3.6V

Current-Sense Amplifier

To minimize power loss of the current sense resistor in

the converter, the RT7205A includes an amplifier with

virtually zero input offset voltage and with a voltage gain of

40. The sensed output current is amplified by the current-

sense amplifier, shown as

“Io_signal ” in Figure 1, which

is then sent to the current-loop regulator for constant-

current regulation and also sent to the MCU, by way of an

10-bit ADC for analog-to-digital conversion, to update the

output current status for the MCU.

External Temperature Sensing

The RT7205A provides the RT pin, as a register-

programmable current source to bias a remote thermal

sensor, such as a thermistor (NTC), as shown in Figure

2. If the RT voltage is below an over-temperature protection

(OTP) threshold and the condition sustains for a

programmed time delay, the OTP will be triggered.

Figure 3. Interface of D+ and D-

DPMDO_LEV

DPOE

DPO

DPPE

DPPO

DPI

RH_DPDM

AIN

MCU

10-bit ADC

SHORT SWITCH

sDPM_SHORT

D+/D-

1.8V 3.3V 4.2V

RL_DPDM

Interface of CC1 and CC2

The CC1 and CC2 pins are used for compliance with USB

Type-C specification. When configured as a Downstream

Facing Port (DFP), three current capabilities of 80

µA,

180

µA, and 330µA, provided by each of the CC pins, will

ROPTO_VDD

VOFFSET_CS = 0.5V

VREF_CC

10-bit DAC

ROPTO_GND

VDD

VFB

IFB

OPTO

CS+

CS-

CS Gain = 40

Io_signal

VDD

UVLO

VDD

UVLO

VREF_CV

10-bit DAC

RFB1

RFB2

RT7205AL Datasheet(PDF) 6 Page - Richtek Technology Corporation

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