CMPWR150TO datasheet(5/8 Pages) CALMIRCO

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CMPWR150

CALIFORNIA MICRO DEVICES

When V

AUX is present, the VCC supply current is less than

10µA until V

CC exceeds VAUX, at which point VCC then powers

the controller (0.15mA). When V

CC reaches VSELECT, the

regulator is enabled.

Typical Transient Characteristics

The transient characterization test set-up shown below

includes the effective source impedance of the V

CC supply

S). This was measured to be approximately 0.2Ω. It is

recommended that this effective source impedance be no

greater than 0.25Ω to ensure precise switching is maintained

during V

CC selection and deselection.

Both the rise and fall times during V

CC power-up/down

sequencing were controlled at a 20 millisecond duration.

This is considered to represent worst case conditions for

most application circuits.

A maximum rated load current of 500mA was used during

characterization, unless specified otherwise.

Typical DC Characteristics (continued)

Figure 4. V

CC Supply Current (No Load).

During a selection or deselection transition, the DC load

current is switching from V

AUX to VCC and vice versa. In

addition to the normal load current, there may also be an

in-rush current for charging/discharging the load capacitor.

The total current pulse being applied to either V

AUX or VCC is

equal to the sum of the dc load and the corresponding in-

rush current. Transient currents in excess of 1.0 amps can

readily occur for brief intervals when either supply

commences to power the load.

The oscilloscope traces of V

CC power-up/down show the

full bandwidth response at the V

CC and VOUT pins under full

load (500mA) conditions.

See Application Note AP-211 for more information.

CC Power-up Cold Start.

Figure 5 shows the output

response during an initial V

CC power-up with VAUX not

present. When V

CC reaches the select threshold, the

regulator turns on. The uncharged output capacitor causes

maximum in-rush current to flow, resulting in a large

voltage disturbance at the V

CC pin of about 230mV. The

built-in hysteresis of 250mV ensures the regulator remains

enabled throughout the transient.

Prior to V

CC reaching an acceptable logic supply level (2V),

a disturbance on the Drive pin can be observed.

Figure 5. V

CC Power-up Cold Start.

CC Supply Current of the device is shown across the entire VCC

range for both V

AUX present (3.3V) and absent (0V) in Figure 4.

In the absence of V

AUX, the supply current remains fixed at

approximately 0.15mA until V

CC reaches the Select voltage

threshold of 4.35V. At this point the regulator is enabled

and a supply current of 1.0mA is conducted.

Transient Characteristics Test Set-up

CMPWR150

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