Atmel ATA6264 - Manual (Page 40)

40
4929B–AUTO–01/07
ATA6264 [Preliminary]
14. Reference Voltage and Reference Current Generation
The pin IREF is an output derived directly from the chip’s internal reference voltage. This refer-
ence source is a band gap. All internally used precise voltages are derived from this band-gap
voltage. At pin IREF a reference resistor of 12.4 k
Ω
has to be applied, providing a reference cur-
rent. All internally used precise currents are derived from this current. In case of a missing
resistor at IREF, the regulators will stop. The power-sequencing block still operates as specified.
A defect of the band-gap reference source can be detected by a microcontroller by comparing
the voltage at IREF with the voltage at pin VINT (Internal 5V supply), because V
VINT
is derived
from a different band gap.
Necessary for operation:
V
EVZ
= 5.5V to 40V or V
K30
= 3.85V to 40V
Operating conditions of all other supply pins:
V
SAT
, V
PERI
and V
CORE
are within functional range limits, T
j
= –40°C to +150°C
Other pins:
As defined in
Section 4. ”Functional Range” on page 8 .
Table 14-1. Truth Table for VINT
State
K30GOOD
(V
K30
> 4.2V to 5V)
K15GOOD
(V
K15
> 3V to 4V) V
EVZ
V
VINT
1 Low Low 0 OFF
2 High Low 0 OFF
3 Low High 0 OFF
4 High High V
EVZ
< V
K30
ON (Supply: K30)
5 Low Low V
EVZ
> 5.5V
ON (Supply: EVZ) – only valid if VINT was
already enabled via state #4
6 High Low V
EVZ
> 5.5V
ON (Supply: EVZ) – only valid if VINT was
already enabled via state #4
7 Low High V
EVZ
> 5.5V
ON (Supply: EVZ) – only valid if VINT was
already enabled via state #4
8 High High V
EVZ
> V
K30
ON (Supply: K30)
Table 14-2. Electrical Characteristics – Reference Voltage and Reference Current Generation
No. Parameters Test Conditions Pin Symbol Min Typ. Max. Unit Type*
13.1 Reference voltage V
IREF
IREF V
IREF
1.24 ± 4% V A
13.2 Reference current IREF IREF I
IREF
100 ± 4% µA A
13.3a Voltage at VINT
V
K30
> V
EVZ
V
K30
= VK30GOOD to 5V
VINT V
VINT
3.35 5.47 V A
13.3b Voltage at VINT V
K30
> V
EVZ
, V
K30
= 5V to 6V VINT V
VINT
3.7 5.47 V A
13.3c Voltage at VINT V
K30
> V
EVZ
, V
K30
= 6V IREF V
IREF
4.2 5.47 V A
13.3d Voltage at VINT
V
EVZ
> V
K30
V
K30
= 0V, V
EVZ
> 6V
IREF V
IREF
4.2 5.47 V A
*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter