MCP37231 datasheet(16/144 Pages) MICROCHIP

16 / 144 page

MCP37231/21-200 AND MCP37D31/21-200

DS20005322D-page 16

 2014-2016 Microchip Technology Inc.

Notes:

When the VCM output is used for the common-mode voltage of analog inputs (i.e. by connecting to the center-tap of a

balun),theVCMpinshouldbedecoupledwitha0.1 µFcapacitor,andshouldbedirectlytiedtotheVCMIN+andVCMIN-pins.

CMOS output mode: WCK/OVR- is WCK and WCK/OVR+ is OVR.

DDR LVDS output mode: The rising edge of DCLK+ is WCK and the falling edge is OVR.

OVR: OVR will be held “High” when analog input overrange is detected. Digital signal post-processing will cause

OVR to assert early relative to the output data. See Figure 2-2 for LVDS timing of these bits.

WCK: WCK is normally “Low”. WCK is “High” while data from the first channel is sent out. In single-channel

mode, WCK stays “High” except when in I/Q output mode. In serialized LVDS (octal) output mode, the WCK out-

put is asserted “High” on the MSb bit. See Section 4.12.5 “Word Clock (WCK)” for further WCK description.

DDR LVDS: Two data bits are multiplexed onto each differential output pair. The output pins shown here are for

the “Even bit first”, which is the default setting of OUTPUT_MODE<1:0> in Address 0x62 (Register 5-20). The

even data bits (Q0, Q2, Q4, Q6, Q8, Q10, Q12, Q14) appear when DCLK+ is “High”. The odd data bits (Q1, Q3,

Q5, Q7, Q9, Q11, Q13, Q15) appear when DCLK+ is “Low”. See Addresses 0x65 (Register 5-23) and 0x68

(Register 5-26) for output polarity control. See Figures 2-2 to 2-6 for LVDS output timing diagrams.

VCMIN is used for Auto-Calibration only. VCMIN+ and VCMIN- should be tied together always. There should be no

voltage difference between the two pins. Typically both VCMIN+ and VCMIN- are tied to the VCM output pin

together, but they can be tied to another common-mode voltage if external VCM is used. This pin has High Z input

in Shutdown, Standby and Reset modes.

Available for the MCP37231-200 and MCP37D31-200 devices only.

Leave these pins floating (No Connect) if not used.

18-bit mode: DM1/DM+ and DM2/DM- are the last LSb bits. DM2/DM- is the LSb. In LVDS output, DM1/DM+ and

DM2/DM- are the LSb pair. DM1/DM+ appears at the falling edge and DM2/DM- is at the rising edge of the DCLK+.

Other than 18-bit mode: DM1/DM+ and DM2/DM- are High Z in LVDS mode.

CAL pin stays “Low” at power-up until the first power-up calibration is completed. When the first calibration has

completed, this pin has “High” output. It stays “High” until the internal calibration is restarted by hardware or a

soft reset command. In Reset mode, this pin is “Low”. In Standby and Shutdown modes, this pin will maintain the

prior condition.

If the SPI address is dynamically controlled, the Address pin must be held constant while CS is “Low”.

The phase of DCLK relative to the data output bits may be adjusted depending on the operating mode. This is

controlled differently depending on the configuration of the digital signal post-processing, PLL and/or DLL. See

also Addresses 0x52, 0x64 and 0x6D (Registers 5-7, 5-22 and 5-28) for more details.

The device is in Reset mode while this pin stays “Low”. On the rising edge of RESET, the device exits Reset

mode, initializes all internal user registers to default values, and begins power-up calibration.

10. (a) SLAVE = “High”: The device is selected as slave and the SYNC pin becomes input pin.

(b) SLAVE = “Low”: The device is selected as master and the SYNC pin becomes output pin. In SLAVE/SYNC

operation, master and slave devices are synchronized to the same clock.

MCP37231 Datasheet(PDF) 16 Page - Microchip Technology