MAX519ACSE データシートの表示（PDF） - Maxim Integrated

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MAX519ACSE

2-Wire Serial 8-Bit DACs with Rail-to-Rail Outputs

Maxim Integrated 

2-Wire Serial 8-Bit DACs with

Rail-to-Rail Outputs

Furthermore if the transmission’s last command byte

has PD high, the output latches are updated, but volt-

age outputs will not reflect the newly entered data

because the DAC enters power-down mode when the

STOP condition is detected. When in power-down, the

DAC outputs float. In this mode, the supply current is a

maximum of 20µA. A command byte with the PD bit low

returns the MAX517/MAX518/MAX519 to normal opera-

tion following a STOP condition, with the voltage out-

puts reflecting the output-latch contents (Figures 10a

and 10b). Because each subsequent command byte

overwrites the previous PD bit, only the last command

byte of a transmission affects the power-down state.

Setting the RST bit high clears the DAC input latches.

The DAC outputs remain unchanged until a STOP con-

dition is detected (Figure 11a). If a reset is issued, the

following output byte is ignored. Subsequent pairs of

command/output bytes overwrite the input latches

(Figure 11b).

All changes made during a transmission affect the

MAX517/MAX518/MAX519’s outputs only when the

transmission ends and a STOP has been recognized.

The R0, R1, and R2 bits are reserved and must be set

to zero.

I2C Compatibility

The MAX517/MAX518/MAX519 are fully compatible

with existing I2C systems. SCL and SDA are high-

impedance inputs; SDA has an open drain that pulls

the data line low during the 9th clock pulse. Figure 12

shows a typical I2C application.

11

(a)

or or

(PD)

0 1 0 AD3 AD2 AD1 AD0 0 0 0 0 0 0 0

0

SDA

XXX

START

CONDITION

ADDRESS BYTE

ACK

COMMAND BYTE

ACK

( ) STOP DEVICE RETURNS TO

CONDITION NORMAL OPERATION

11

(b)

or or

(PD)

0 1 0 AD3 AD2AD1 AD0 0 0 0 0 0 0 0

00 00000000 0

SDA

XX

START

CONDITION

ADDRESS BYTE

NOTE: X = DON'T CARE

ACK

COMMAND BYTE

ACK

(ADDRESSING DAC0)

OUTPUT BYTE

ACK

(SET TO 0)

STOP

DAC0 INPUT

CONDITION

( ) LATCH SET TO 0. DEVICE RETURNS TO NORMAL OPERATION.

( ) DAC0 SET TO 0.

Figure 10. Returning to Normal Operation from Power-Down

11

(a)

or or

(RST)

0 1 0 AD3 AD2 AD1AD0 0 0 0 0 0 1 0

0

SDA

XXX

ADDRESS BYTE

ACK

COMMAND BYTE

ACK

START

STOP

CONDITION

(b)

11

or or

ALL INPUT LATCHES CONDITION

( ) SET TO 0.

ALL OUTPUTS

( ) (RST)

SET TO 0.

0 1 0 AD3 AD2 AD1 AD0 0 0 0 0 0 1 0

0

0

SDA

XXX XXXXXXXX

START

CONDITION

ADDRESS BYTE

NOTE: X = DON'T CARE

ACK

COMMAND BYTE

ACK

"DUMMY"

OUTPUT BYTE

( ) ALL INPUT LATCHES

SET TO 0.

ACK ADDITIONAL

COMMAND BYTE/

OUTPUT BYTE PAIRS

STOP

CONDITION

( ) DAC OUTPUTS SET TO 0 UNLESS

CHANGED BY ADDITIONAL COMMAND

BYTE/OUTPUT BYTE PAIRS.

Figure 11. Resetting DAC Outputs

______________________________________________________________________________________ 11

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