MCP4162T-502I/SL View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

MCP4162T-502I/SL

7/8-Bit Single/Dual SPI Digital POT with Volatile Memory

Microchip Technology 

MCP413X/415X/423X/425X

7.8 Decrement Wiper

Normal and High Voltage

Note:

The High Voltage Decrement Wiper

command is supported for compatability

with system that also support MCP414X/

416X/424X/426X devices.

The Decrement Command is an 8-bit command. The

Decrement Command can only be issued to wiper

memory locations. The format of the command is

shown in Figure 7-6.

An Decrement Command to the wiper memory location

changes that location after a properly formatted

command (8-clocks) have been received.

Decrement commands provide a quick and easy

method to modify the value of the wiper location by -1

with minimal overhead.

COMMAND BYTE

(DECR COMMAND (n+1))

AAAA1 0XX

SDI D D D D

3210

1 1 1 1 1 1 1* 1 Note 1, 2

SDO

1 1 1 1 1 1 0 0 Note 1, 3

Note 1: Only functions when writing the volatile

wiper registers (AD3:AD0) 0h and 1h.

2: Valid Address/Command combination.

3: Invalid Address/Command combination

all following SDO bits will be low until the

CMDERR condition is cleared.

(the CS pin is forced to the inactive

state).

4: If a Command Error (CMDERR) occurs

at this bit location (*), then all following

SDO bits will be driven low until the CS

pin is driven inactive (VIH).

FIGURE 7-8:

Decrement Command -

SDI and SDO States.

7.8.1 SINGLE DECREMENT

Typically the CS pin starts at the inactive state (VIH), but

may be already be in the active state due to the

completion of another command.

Figure 6-7 through Figure 6-8 show possible

waveforms for a single Decrement. The decrement

operation requires that the CS pin be in the active state

(VILor VIHH). Typically the CS pin will be in the inactive

state (VIH) and is driven to the active state (VILor VIHH).

Then the 8-bit Decrement Command (Command Byte)

is clocked in on the SDI pin by the SCK pins. The SDO

pin drives the CMDERR bit on the 7th clock.

The wiper value will decrement from the wipers

Full-Scale value (100h on 8-bit devices and 80h on

7-bit devices). Above the wipers Full-Scale value

(8-bit =101h to 1FFh, 7-bit = 81h to FFh), the

decrement command is disabled. If the Wiper register

has a Zero Scale value (000h), then the wiper value will

not decrement. See Table 7-4 for additional information

on the Decrement Command vs. the current volatile

wiper value.

The Decrement commands only require the Decrement

command byte, while the CS pin is active (VILor VIHH)

for a single decrement.

After the wiper is decremented to the desired position,

the CS pin should be forced to VIH to ensure that

unexpected transitions on the SCK pin do not cause

the wiper setting to change. Driving the CS pin to VIH

should occur as soon as possible (within device

specifications) after the last desired decrement occurs.

TABLE 7-5: DECREMENT OPERATION VS.

VOLATILE WIPER VALUE

Current Wiper

Setting

7-bit 8-bit

Pot Pot

Wiper (W)

Properties

Decrement

Command

Operates?

3FFh 3FFh Reserved

No

081h 101h (Full-Scale (W = A))

080h 100h Full-Scale (W = A)

Yes

07Fh 0FFh W = N

041h 081

040h 080h W = N (Mid-Scale)

Yes

03Fh 07Fh W = N

001h 001

000h 000h Zero Scale (W = B)

No

© 2008 Microchip Technology Inc.

DS22060B-page 57

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