CAUTION

The module has approximately 40∝F of internal capacitance across the VCC pins. During initial power-up the host power supply will have to charge this capacitance to the operating voltage. This initial in-rush current may exceed the module’s normal peak current, sometimes greater than an order of magnitude higher (depending upon the power supply design) for a short duration (generally a few microseconds).

5.6 Voltage Reference (VREF)

Pin

 

Name

 

Direction

 

Function

 

 

 

 

 

 

 

34

 

VREF

 

Input (Output)

 

Core voltage reference

GR64 provides a voltage reference interface for user applications.

Level shifters are integrated in the GR64 product. The integrated level shifters are referenced to an internal IO regulator on the module side and to an application voltage on the user side of the interface. There are two implementation of VREF, dependent upon the users’ GR64 variant;

•VREF as an output (DPY 102 1494/10 & DPY 102 1494/30 variants)

•VREF as an input (DPY 102 1494/20 & DPY 102 1494/40 variants)

5.6.1VREF as an Output

The version of GR64 without an integrated SIM holder provides a 2.8V reference to the host side level shifter devices. This enables legacy users, and users of older interface technology to connect directly to the GR64’s IO. The same reference voltage is provided as an output on VREF. In this arrangement VREF can be used as a further level shifter reference in the users application circuits, or to power external circuits, since it has a 75mA current sourcing capability.

VREF output

Parameter

 

Min

 

Nom

 

Max

 

Unit

 

 

 

 

 

 

 

 

 

VREF output voltage

 

2.74

 

2.8

 

2.86

 

V

VREF load current

 

 

 

 

75

 

mA

5.6.2 VREF as an Input

The version of GR64 with an integrated SIM holder provides a reference input to the host side level shifter devices. This enables users of varying technologies to connect directly to the GR64’s IO by providing a reference from their own application IO.

LZT 123 1834

39