900844 Datasheet, PDF (57/118 Pages) Freescale Semiconductor, Inc – Integrated Power Management IC for Ultra-mobile and Embedded Applications

FUNCTIONAL DEVICE OPERATION
POWER SUPPLIES
DC/DC POWER SUPPLIES
Freescale’s power management solution for the Ultra-mobile platform for Netbook/Tablets and Slates, includes 5 DC/DC
switching regulators integrated on the 900844 PMIC. the five DC-DC regulators are Buck converters, and these can be set to
work in the following operation modes:
Buck converters Operation Modes Selections (VCC, VNN, VDDQ, V21, V15)
• OFF - The regulator is switched off and the output voltage is discharged.
• PFM - The regulator is switched on and set to PFM mode operation. In this mode, the regulator is always running in PFM
mode. Useful at light loads for optimized efficiency.
• Automatic Pulse Skip - The regulator is switched on and set to Automatic Pulse Skipping. In this mode, the regulator moves
automatically between pulse skipping and full PWM mode depending on load conditions.
• PWM - The regulator is switched on and set to PWM mode. In this mode, the regulator is always in full PWM mode operation
regardless of load conditions.
• TEST/TRIM - This is not a functional mode, thus requiring certain steps to prevent unintentional activation of this mode. During
this mode, the device performs measurements and trimming.
DC-DC Power Supply Summary Table
Table 24 provides a summary of all DC/DC regulators on the 900844.
Table 24. 900844 DC-DC power supplies.
Regulator
Typ. Voltage
Max Continuous
Current
Description
VCC
0.3 - 1.2 V
3.5 A
1.0 MHz synchronous Buck converter with external switching MOSFETs.
Internally compensated.
VID is controlled using a shared 7-bit bus for voltage coding and 2 VID enable
signals for VCC or VNN selection.
VNN
0.3 - 1.2 V
1.6 A
1.0 MHz synchronous Buck converter with external switching MOSFETs.
Internally compensated.
VID is controlled using a shared 7-bit bus for voltage coding and 2 VID enable
signals for VCC or VNN selection.
VDDQ
1.8 V/1.5 V
1.3 A
4.0 MHz fully integrated 2-switch synchronous Buck PWM voltage mode control
DC/DC regulator.
V21
2.1 V
1.0 A
4.0 MHz fully integrated 2-switch synchronous Buck PWM voltage mode control
DC/DC regulator.
V15
1.5 V
1.5 A
4.0 MHz fully integrated 2-switch synchronous Buck PWM voltage mode control
DC/DC regulator.
Note that all of the DC/DC regulators specify an extended input voltage range beyond the 3.0 to 4.4 V applications range.
Below this, extended range functionality is maintained, but parametric performance could be compromised.
VCC
This is a VID controlled single-phase 1.0 MHz 2-switch synchronous Buck PWM voltage mode control DC/DC regulator,
designed to power high performance CPUs. VCC uses external MOSFETs, P-Ch high side and N-Ch low side.
VCC includes support for VID active voltage positioning requirements. A 7-bit DAC reads the VID input signals and sets the
output voltage level. The output voltage has a range of 0.3 to 1.2 V. The programming step size is 12.5 mV. Values will be read
in real time and will be stored in internal registers not accessible to the system host. Reference VIDEN[1:0] & VID[6:0] Pins for
more details.
The same VID input signals are shared between VCC and VNN, where a latch signal for each regulator decides which
regulator takes control of the VID input signals.
The DAC value represents the output voltage value. The output voltage node is connected directly to the inverting input of the
error amplifier that uses the DAC output as its reference, unity gain configuration. Using this configuration with internal
compensation eliminates the need for the feedback and compensation network, which saves board space and cost. The DAC/
output voltage slew rate is internally set 25 mV/µs to minimize transient currents and audible noise.
Analog Integrated Circuit Device Data
Freescale Semiconductor
900844
57