12 - 10

For price, delivery and to place orders: Hittite Microwave Corporation, 20 Alpha Road, Chelmsford, MA 01824

Phone: 978-250-3343

Fax: 978-250-3373

Order On-line at www.hittite.com

Application Support: Phone: 978-250-3343 or apps@hittite.com

12

Serial Control Interface

The HMC743LP6C(E) contains a 3-wire SPI compatible digital interface (SERIN, CLK, LEA (or LEB)) that is used to

control the input and output gain control elements (digital attenuators). The input (IN) and output (OUT) attenuators

can be individually controlled thru the latch enable pins. The LEA pin latches the serial 6-bit control word to the output

attenuator. The LEB pin latches the serial 6-bit control word to the input attenuator.

The 6-bit serial word can be loaded either MSB first or LSB first depending on the state of the BO (bit order) pin.

Setting BO to high configures the serial controller to operate in LSB first mode. Setting BO to low configures the serial

controller to operate in MSB first mode.

When LEA or LEB (or both) is raised to a logic high, 6-bit data in the serial input register is transferred to the input

attenuator or the output attenuator (or both). While either LEA or LEB are high, CLK signal must be masked or stopped

to prevent data transition during output loading.

Parameter

Typ.

Min. serial period, t

SCK

100 ns

Control set-up time, t

Cs

20 ns

Control hold-time, t

CH

20 ns

LE setup-time, t

ln

10 ns

Min. LE pulse width, t

LEW

10 ns

Min LE pulse spacing, t

les

630 ns

Serial clock hold-time from LE, t

CKN

10 ns

HMC743LP6C / 743LP6CE

v04.0311

0.5 dB LSB GaAs MMIC DUAL 6-BIT DIGITAL

VARIABLE GAIN AMPLIFIER, DC - 4 GHz

PUP Truth Table

le

(A and B)

pUp1

pUp2

Gain Relative to Max Setting

0

0

0

-63 db

0

1

1

0 db

Power-Up States

The HMC743LP6C offers two different power up

states, either full attenuation or maximum gain mode.

See truth table.

Power-On Sequence

The ideal power-up sequence is: GND, Vdd, digital

inputs, RF inputs. The relative order of the digital

inputs are not important as long as they are powered

after Vdd / GND

Timing Diagram

Timing diagram is used for either input or output digital

gain control. Control word is shown with MSB first (BO

= Low) configuration.