1−5

1.5

Terminal Functions (Continued)

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

VCC

10,39,62

—

Power supply input, 3.3 V typical

VDD18†

37

1.8 V. When VREN is low, 1.8 V must be applied to provide current for the core during suspend.

VREN

38

I

Voltage regulator enable: enable active LOW; disable active HIGH

X2

60

O

12-MHz crystal output

X1

61

I

12-MHz crystal input

† During normal operation, the internal 3.3- to 1.8-V voltage regulator of the TUSB2136 is enabled and provides power to the core. To save power

during the suspend mode, the internal regulator is disabled. In this case, the pin becomes an input, and a simple external power source is required

to provide power to the core. This source needs to supply a very limited amount of power (10

µA maximum) within the voltage range of 1 V to

1.95 V.

NOTE 1: The MCU treats the outputs as open-drain types in that the output can be driven low continuously, but a high output is driven for two

clock cycles and then the output is placed in a high-impedance state.

TEST0

TEST1

FUNCTION

0

0

Selects 48-MHz clock input (from an oscillator or other onboard clock source)

0

1

Reserved for testing purposes

1

0

Reserved for testing purposes

1

1

Selects 12-MHz crystal as clock source (default)

1.6

Revision History

Version

Date

Changes

Dec−2000

Initial Release

A

Feb−2001

1.

Clarified pin descriptions for P3.2 (56), P3.3 (55), and VDDOUT (37).

2.

Add red/write capability for each of the register bits.

3.

Corrected Quiescent and Suspend current figures in Table 3.3.

4.

Added Section 4.2 Reset Timing

5.

Added NOTE to cover page.

B

Jun−2002

1.

Changed name of pin 37 from VDDOUT to VDD18 and enhanced pin description.

2.

Removed NOTE from cover page.

C

Apr−2003

1.

Simplified Terminal Function Table for GPIO Ports

2.

Clarified GPIO Port 3 pin descriptions in Terminal Function Table

3.

Clarified functional description for Pins S2 and S3 (8 & 9)

4.

Clarified TEST0 & TEST1 (14 & 15) pin functions in Terminal Functions Table

5.

Added note on open-drain output pins for Terminal Functions Table

6.

Added additional note for operation of VDD18 (pin 37) to Terminal Functions Table.

7.

Removed most references to ROM version including Fig 2.2.

8.

Added USB Logo to Cover page