Peripheral application circuit

Abstract

The embodiment of the invention discloses a peripheral application circuit, which is applied to a JV700 chip to avoid an error action of the JV700 chip at the initial powered-on state, so as to prevent the inside of the chip from anomaly and protect the chip from damage. The peripheral application circuit provided by the embodiment of the invention comprises an initial state determination module and a power supply control module, wherein the initial state determination module is respectively connected to an enable analog switch output pin, a power-on reset and chip enable pin and an IO (Input-Output)_10 pin of the JV700 chip, and is used for pulling the voltage of the pins connected to the initial state determination module up to a preset voltage or pulling the voltage of the pins down to ground; the power supply control module is connected to a power supply input terminal of the JV700 chip, and is used for performing power supply control on the JV700 chip through a micro control unit (MCU).

Description

technical field [0001] The invention relates to the field of automobile diagnosis, in particular to a peripheral application circuit of a JV700 chip. Background technique [0002] JV700 analog processing chip is an automotive-specific diagnostic chip that integrates analog switch arrays and various communication buses and transceivers, and is oriented to the entire system and vehicle series; this chip is compatible with automotive on-board automatic diagnostic systems (OBD, On-Board Diagnostics) The input / output (IO, Input / Output) ports on the diagnostic seat correspond one by one, and are suitable for all vehicles with 16PIN standard OBDII interface; [0003] There are few application circuits around the existing JV700 chip, please refer to figure 1 , figure 1 It is a connection schematic diagram of a peripheral application circuit of the existing JV700 chip, in which, 1-13 pins are 13 IO ports. Usually, the design of the 13 IO ports of the JV700 chip is to directly conne...

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Problems solved by technology

[0003] There are few application circuits around the existing JV700 chip, please refer to figure 1 , figure 1 It is a connection schematic diagram of a peripheral application circuit of the existing JV700 chip, in which, 1-13 pins are 13 IO ports. Usually, the design of the 13 IO ports of the JV700 chip is to directly connect it with the IO port of the car OBD diagnostic socket. Port one-to-one connection, 21\22\23 pins corresponding to V8(8V)\V5(5V)\V3(3.3V) are respectively the power supply of low dropout linear regulator (LDO, Low drop outregulator) inside JV700 chip, No external power supply, only for the use of the analog devices inside the JV700 chip, only need to connect a 2.2uF filter capacitor externally; between 14-pin (SCANH, Inductor and capacitor connection of SCAN) and 28-pin (IND, Inductor connection of SCAN) An inductor (10uH ~ 22uH) needs to be connected in series, and then a 220PF capacitor is connected in parallel to the ground (GND, Ground). This part is mainly responsible for the function of the single-wire controller area network (CAN, Controller Area Network). Without this inductor and capacitor, Single-line CAN will not be able to communicate; and between 43-pin \K (K-line external1K resistor connection pin) and 44-pin \VOK (Internal K-line voltage source), 45-pin \L (L-line external 1K resistor connection pin) A 1k matching resistor needs to be connected in series with 46 pin \VOL (Internal L-line voltage source)

[0004] However, the inventor found in the process of implementing the embodiment of the present invention that the internal analog switch of the JV700 chip may malfunction at the moment of power-on, that is, in the initial state of power-on, resulting in uncontrollable internal chip or other misoperations that may damage the chip

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