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33394

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

4.2.6. Switching Regulator Output Voltage Sense

(VPRE_S)

This is the switching regulator output voltage sense input.

The switcher output voltage VPRE is divided by an internal

resistor divider and compared with the bandgap reference

voltage (see Figure 4).

Refer to Section 5 Application Information for detailed

description of the switching regulator operation.

Figure 4. Switching Regulator Block Diagram

BUCK &

BOOST

CONTROL

LOGIC

CURRENT

LIMIT

SOFT

START

–

FEED

FORWARD

RAMP

GENERATOR

THERMAL

LIMIT

SWITCHER

OSCILLATOR

200 kHz

SWITCHER

MODE

ENABLE

Vbg

–

PWM

COMP

Vbg

VPRE

COMP

BOOTSTRAP

VBAT

–

BOOST

COMP

Vbg

1.25 V

Vbg

1.25 V

Vbg

1.25 V

E/A

DRIVER

VPRE

BOOT

SW1

VPRE

SW2G

VPRE_S

INV

VCOMP

40 k

11.7 k

4.3. Voltage Regulator (VDDH)

The VDDH output is a linearly regulated +5.0 +/– 0.10V

voltage supply capable of sourcing a maximum of 400 mA

steady state current from VPRE (+5.6 V) for VBAT voltages

from +4.0 V to +26.5 V (+45V transient). This regulator

incorporates current limit short circuit protection and thermal

shut down protection. The voltage output is stable under all

load/line conditions. However, the designer must consider

ripple and high frequency filtering as well as regulator

response, when choosing external components. See Table 1

in the Applications Information section for recommended

output capacitor parameters.

NOTE :

Backfeeding into the VDDH output can cause problems

during the power up sequence. Refer to the Electrical

Characteristics VDDH Regulator Section for the maximum

allowed backfed current into the VDDH output.

4.4. Tracking Voltage Regulator (VPP)

This linearly regulated +5.0 V/+3.3 V (SPI selectable)

voltage supply is capable of sourcing 150 mA of steady state

current from VPRE (+5.6 V) for VBAT voltage from +4.0 V to

+26.5 V (up to +45V transient). It tracks the VDDH or VDD3_3

output, and incorporates current limit short circuit protection

and over temperature shut down protection. This output is

intended for FLASH memory programming and includes a

dedicated enable pin (VPP_EN). The regulator enable can

also be controlled through the SPI interface but requires both

the VPP_EN pin and the SPI bit (EN_VPP bit) to be high to

enable. The selection of tracking VDDH or VDD3_3 is

controlled by the VPP_V bit in the SPI. Logic “1” selects VDDH

(default), logic “0” selects VDD3_3. The voltage output is

stable under all load/line conditions. However, the designer

must consider ripple and high frequency filtering as well as

regulator response when choosing external components. See

Table 1 for recommended output capacitor parameters.

The VPP tracking regulator should not be used in parallel

with the VDDH regulator, because this arrangement can

corrupt the proper power sequencing of the IC.

4.5. Tracking Voltage Regulator (VREFn)

The outputs of the VREF1, VREF2, VREF3 linear regulators

are 100 mA at +5.0 V. They track the VDDH output. The power

supplies are designed to supply power to sensors that are

located external to the module. These regulators may be

enabled or disabled via the SPI, which also provides fault

reporting for these regulators. They are protected for short to

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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