for two’s complement (G/T = 0)

output code as shown in Table 2.

Digital outputs D11–D0 are high impedance when the

MAX1209 is in power-down (PD = high). D11–D0 transi-

tion high 10ns after the rising edge of PD and become

active 10ns after PD’s falling edge.

Keep the capacitive load on the MAX1209 digital out-

puts D11–D0 as low as possible (<15pF) to avoid large

digital currents feeding back into the analog portion of

the MAX1209 and degrading its dynamic performance.

The addition of external digital buffers on the digital

outputs isolates the MAX1209 from heavy capacitive

loading. To improve the dynamic performance of the

MAX1209, add 220

Ω resistors in series with the digital

outputs close to the MAX1209. Refer to the MAX1211

evaluation kit schematic for an example of the digital

outputs driving a digital buffer through 220

Ω series

resistors.

VV

V

V

CODE

INP

INN

REFP

REFN

(

)

−=

−

×

×

2

4096

10

12-Bit, 80Msps, 3.3V IF-Sampling ADC

18

______________________________________________________________________________________

GRAY CODE OUTPUT CODE (G/

T = 1)

TWO’S-COMPLEMENT OUTPUT CODE (G/

T = 0)

BINARY

D11

➝D0

DOR

HEXADECIMAL

EQUIVALENT

OF

D11

➝D0

DECIMAL

EQUIVALENT

OF

D11

➝D0

BINARY

D11

➝D0

DOR

HEXADECIMAL

EQUIVALENT

OF

D11

➝D0

DECIMAL

EQUIVALENT

OF

D11

➝D0

1000 0000 0000

1

0x800

+4095

0111 1111 1111

1

0x7FF

+2047

>+1.0235V

(DATA OUT OF

RANGE)

1000 0000 0000

0

0x800

+4095

0111 1111 1111

0

0x7FF

+2047

+1.0235V

1000 0000 0001

0

0x801

+4094

0111 1111 1110

0

0x7FE

+2046

+1.0230V

1100 0000 0011

0

0xC03

+2050

0000 0000 0010

0

0x002

+2

+0.0010V

1100 0000 0001

0

0xC01

+2049

0000 0000 0001

0

0x001

+1

+0.0005V

1100 0000 0000

0

0xC00

+2048

0000 0000 0000

0

0x000

0

+0.0000V

0100 0000 0000

0

0x400

+2047

1111 1111 1111

0

0xFFF

-1

-0.0005V

0100 0000 0001

0

0x401

+2046

1111 1111 1110

0

0xFFE

-2

-0.0010V

0000 0000 0001

0

0x001

+1

1000 0000 0001

0

0x801

-2047

-1.0235V

0000 0000 0000

0

0x000

0

1000 0000 0000

0

0x800

-2048

-1.0240V

0000 0000 0000

1

0x000

0

1000 0000 0000

1

0x800

-2048

<-1.0240V

(DATA OUT OF

RANGE)

Table 2. Output Codes vs. Input Voltage

(

)