CMPWR300 Ver la hoja de datos (PDF) - California Micro Devices Corp
Número de pieza
componentes Descripción
Fabricante
CMPWR300 Datasheet PDF : 11 Pages
| |||
CALIFORNIA MICRO DEVICES
CMPWR300
Typical Transient Characteristics
The transient characterization test setup shown below includes
the effective source impedance of the VCC supply (RS). 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 VCC selection
and deselection.
Both the rise and fall times during VCC power-up/down
sequencing were controlled to be around 10 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.
During a selection or deselection transition the DC load current
is switching from VAUX to VCC and vice versa, or from VSBY to
VCC. 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
VAUX or VCC is equal to the sum of the dc load and the
corresponding in-rush current. Transient currents in excess
of one amp can readily occur for brief intervals when either
supply commences to power the load.
The oscilloscope traces of VCC power-up/down show the full
bandwidth response at the VCC and VOUT pins under full load
(500mA) conditions.
See Application note AP-211 for more details.
Cold Start and Full Power Down (Fig 2.1 to 2.6)
Cold start power up and power down from VCC, VSBY and
VAUX. The output voltage follows the input very smoothly
with no disturbance. As soon as the VCC or VSBY input voltage
reaches about 2V, VOUT starts rising. It reaches 3.3V when
VCC or VSBY equals 3.8V. VOUT remains valid until VCC or VSBY
drops below 3.8V.
VCC Power Changeover (Fig 2.7 to 2.12)
Power transitions between the main VCC and the standby or
the auxiliary sources under 375mA load. The transition
between VCC and VSBY shows a small disturbance of 80mV
on VOUT.
Transitions between VCC and VAUX show a disturbance of
about 120mV on VOUT. During power up condition, VCC
experiences 100mV disturbance.
This is due to the in-rush current during the power switching.
The built-in hysteresis of 300mV ensures the regulator
remains turned on throughout the transient.
Load and Line Transient Response (Fig 2.13 to 2.16)
The load transient response shows a 5mA to 500mA step
load with minimal disturbance on VOUT of 80mV. An initial
transient overshoot of 80mV occurs and the output settles
to its final voltage within a few microseconds. The dc voltage
disturbance on the output is approximately 25mV, which
demonstrates the regulator output impedance of 50mW.
The line step response shows a small disturbance of 25mV
on the output when VCC steps from 4.5V to 5.5V. When
falling from 5.5V to 4.5V, the output is almost unchanged
©2000 California Micro Devices Corp. All rights reserved.
6
215 Topaz Street, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
12/5/2000
Share Link: 