___________________________MAX2233

Digital Gain Control

and Power Management

The MAX2233 responds to logic-level signals at the

device’s 2-bit DAC inputs, D0 and D1, placing the

device in shutdown mode or into one of three discrete

output power levels. See Table 2 for operating modes

and output power levels. Setting D0 and D1 to a logic-

level low places the device in shutdown mode and

reduces supply current to 0.2µA. The VGA, driver, and

output stage are off in shutdown mode, while the input

impedance is only slightly changed. Setting D0 and D1

to one of the other three modes adjusts the output

power to one of three discrete levels in 10dB steps.

Thermal Shutdown

The MAX2232/MAX2233 feature a thermal shutdown

mode that helps to protect the device from damage

when the die temperature becomes excessive. If the

temperature of the die exceeds the thermal shutdown

mode and output power is reduced to a minimum. After

remains in thermal shutdown mode for the thermal shut-

timeout period helps to limit device thermal cycling that

results if the source of the excessive temperature is not

Applications Information

Proper attention to voltage supply bypassing is essen-

with 0.1µF, 10nF, and 100pF capacitors in parallel with

each other to ground. Use separate vias to the ground

plane for each of the bypass capacitors and minimize

trace length to reduce inductance. Use separate vias to

the ground plane for each ground pin. Use low-induc-

tance ground connections.

Decouple SHDN, CTRL, D0, and D1 with 0.1µF capaci-

tors to ground to minimize noise on the internal bias cell.

Use a series resistor (typically 100

Ω) to further reduce

coupling of high-frequency signals into the control pins.

900MHz ISM-Band, 250mW Power Amplifiers

with Analog or Digital Gain Control

_______________________________________________________________________________________

7

MODE

Standby

> 2.0V

< 0.6V

X

≤ 0.4V

OUTPUT POWER

< -35dBm

< -35dBm

Variable Gain

> 2.0V

0.6V

< 2.2V

0dBm to +24dBm

Maximum Gain

> 2.0V

> 2.2V

+24 dBm

Shutdown

Table 1. MAX2232 Operating Modes

X = Don’t care

Table 2. MAX2233 Operating Modes

Truth Table

MODE

Shutdown

Low Power

0

0

D1

D0

0

1

OUTPUT POWER

< -35dBm

+6.5dBm

Medium Power

1

0

+15dBm

High Power

1

1

+24dBm

Functional Diagrams

MAX2232

VGA

DRIVER

TEMP

SENSOR

RFOUT

TSET

2

16

15

5, 6

7, SLUG

8

10

SHDN

RAMP+

14

3

11

12

1

13

RAMP-

4

CTRL

RFIN

BIAS

GND

GND

GND

GND

TSET

MAX2233

VGA

DRIVER

TEMP

SENSOR

RFOUT

2

16

15

5, 6

7, SLUG

10

D0

4

3

11

12

1

D1

RFIN

BIAS

GND

GND

GND

GND

8

2-BIT

DAC