Datasheet
Analog Integrated Circuit Device Data
73 Freescale Semiconductor
MC34708
Functional Block Description
7.5.6.9 VGEN1, VGEN2
General purpose LDOs, VGEN1, and VGEN2, are provided for expansion of the power tree to support peripheral devices, which
could include EMMC cards, WLAN, BT, GPS, or other functional modules. These regulators include programmable set points for
system flexibility. VGEN1 has an internal PMOS pass FET, and is powered from the SW5 buck for an efficiency advantage and
reduced power dissipation in the pass devices. VGEN2 is powered directly from the battery.
VGEN2 has an internal PMOS pass FET, which will support loads up to 50 mA. For higher current capability, drive for an external
PNP is provided. The external PNP is offered to avoid excess on-chip power dissipation at high loads and large differentials
between BP and the output settings. The input pin for the integrated PMOS option is shared with the base current drive pin for
the PNP option. The external PNP device is always 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
the ON Semiconductor NSS12100UW3TCG. For stability, a total resistance of 60 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.
The nominal output voltage of VGEN1 is SPI configurable, and can be 1.2 V, 1.25 V, 1.3 V, 1.35 V, 1.4 V, 1.45 V, 1.5 V, or
1.55
V.
VDAC ACTIVE MODE – AC (CONTINUED)
VDAC
OS-
START
Start-up Overshoot
•V
IN
= V
INMIN
, V
INMAX
IL = 0
- 1.0 2.0
%
VDAC
LO
TRANSIENT
Transient Load Response
•V
IN
= V
INMIN
, V
INMAX
- 1.0 2.0
%
V
DACLI
TRANSIENT
Transient Line Response
•IL = 75% of IL
MAX
- 5.0 8.0
mV
t
MODE-VDAC
Mode Transition Time
• From low power to active V
IN
= V
INMIN
, V
INMAX
IL = IL
MAXLP
- - 100
µs
VDAC
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 63. VGEN1 Control Register Bit Assignments
Parameter Value Output Voltage ILoad max
VGEN1[2:0] 000 1.2000 250 mA
001 1.2500 250 mA
010 1.3000 250 mA
011 1.3500 250 mA
100 1.4000 250 mA
101 1.4500 250 mA
110 1.5000 250 mA
111 1.5500 250 mA
Table 62. VDAC 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