Datasheet
Analog Integrated Circuit Device Data
71 Freescale Semiconductor
MC34708
Functional Block Description
7.5.6.8 VDAC
The primary applications of this power supply is the TV-DAC. However, these supplies could also be used for other peripherals
if one of these functions is not required. Low Power modes and programmable standby options can be used to optimize power
efficiency during deep sleep modes.
An external PNP is utilized for VDAC to avoid excess on-chip power dissipation at high loads and large differentials between BP
and output settings. External PNP devices must always be connected to the BP line in the application. The recommended PNP
device is the ON Semiconductor NSS12100XV6T1G, which is capable of handling up to 250
mW of continuous dissipation at
minimum footprint and 75 °C of ambient. For use cases where up to 500 mW of dissipation is required, the recommended PNP
device is ON Semiconductor NSS12100UW3TCG. For stability reasons, a total resistance of 100
m 20% in series with the
output capacitance is required. The total resistance includes the ESR of the capacitor plus an external resistance provided by a
discrete resistor or PCB circuit trace.
A short-circuit condition will shut down the VDAC regulator and generate an interrupt for SCPI, if the REGSCPEN bit is set.
The nominal output voltage of this regulator is SPI configurable, and can be 2.5 V, 2.6 V, 2.7 V, or 2.775 V. The maximum output
current along with an external PNP, is 250
mA.
VUSB2 LOW POWER MODE - DC
V
USB2
Output Voltage V
OUT
•V
INMIN
< V
IN
< V
INMAX
IL
MINLP
< IL < IL
MAXLP
V
NOM
- 3% V
NOM
V
NOM
+ 3%
V
I
USB2
Current Load Range IL
MINLP
to IL
MAXLP
0.0 - 3.0 mA
I
USB2Q
Low Power Mode Quiescent Current
•V
INMIN
< V
IN
< V
INMAX
IL = 0
- 8.0 10.5
µA
VUSB2 ACTIVE MODE - AC
VUSB2
PSRR
PSRR, IL = 75% of IL
MAX
20 Hz to 20 kHz
•V
IN
= V
INMIN
+ 100 mV
•V
IN
= V
NOM
+ 1.0 V
-
-
30
30
-
-
dB
t
ON-VUSB2
Turn-on Time
• Enable to 90% of end value V
IN
= V
INMIN
, V
INMAX
IL = 0
- - 1.0
ms
t
OFF-VUSB2
Turn-off Time
• Disable to 10% of initial value V
IN
= V
INMIN
, V
INMAX
IL = 0
0.05 - 10
ms
VUSB2
OS-
START
Start-up Overshoot
•V
IN
= V
INMIN
, V
INMAX
IL = 0
- 1.0 2.0
%
VUSB2
LO
TRANSIENT
Transient Load Response, V
IN
= V
INMIN
, V
INMAX
x
• VUSB2=01, 10, 11
• VUSB2=00
-
-
1.0
50
2.0
70
%
mV
VUSB2
LI
TRANSIENT
Transient Line Response
•IL = 75% of IL
MAX
- 5.0 8.0
mV
t
MOD-VUSB2
Mode Transition Time
• From low power to active and from active to low power
V
IN
= V
INMIN
, V
INMAX
IL = IL
MAXLP
- - 100
µs
VUSB
MODE
RES
Mode Transition Response
• From low power to active and from active to low power
V
IN
= V
INMIN
, V
INMAX
IL = IL
MAXLP
- 1.0 2.0
%
Table 60. VUSB2 Electrical Specification
Characteristics noted under conditions BP = 3.6 V, V
BUS
= 5.0 V, - 40 C T
A
85 C, unless otherwise noted. Typical values
at BP = 3.6 V and T
A
= 25 °C under nominal conditions, unless otherwise noted.
Symbol Characteristic Min Typ Max Unit Notes