mc33702 Freescale Semiconductor, Inc, mc33702 Datasheet - Page 18

• Manufacturer Part Number: mc33702
• Description: 3.0 A Switch-mode Power Supply With Linear Regulator
• Manufacturer: Freescale Semiconductor, Inc

33702
18
Shorted Load
Inverted Operating Mode
1. Single 3.3 V Supply, V
supplies core voltage (e.g., 1.8 V nominal), and the switcher
V
on the normal LDO intrinsic operation to control the Pass FET.
Power Up
point and the Pass FET will be on. In order not to exceed the
2.0 V differential requirement between the I/O (V
core (LDO), the LDO must start up at 2.0 V or less and be able
to maintain the 2.0 V or less differential. The maximum slew
rate for V
Power Down
therefore the Pass FET will be on. In the case where LDO is
falling faster than V
LDO. In the case where V
FET is also on, and the LDO load capacitor will be discharged
through the Pass FET to V
too fast, the core voltage (LDO) will not exceed the I/O voltage
(V
Shorted Load
OUT
1. V
2. LDO shorted to ground. The switcher uses control
3. V
4. V
5. V
6. LDO shorted to supply. No load protection. 33702
IN
1. LDO shorted to ground. This will cause the I/O voltage to
2. V
The 3.3 V supplies the microprocessor I/O voltage, the LDO
When V
When V
) by more than maximum of 0.4 V.
exceed the core voltage by more than 2.0 V. No load
protection.
discharged, the core voltage will exceed the I/O voltage
by more than 0.4 V. By the intrinsic operation of the LDO,
(2) described in the
methods (4) and (5) described in the
section, page 16.
output shorted to ground.
output shorted to ground.
protected by current limit and thermal limit.
protected by current limit and thermal limit.
operates independently. Power sequencing depends only
OUT
IN1
IN2
OUT
IN
IN
shorted to ground. Until the LDO load capacitance is
shorted to ground. This is equivalent to the LDO
shorted to ground. This is equivalent to the switcher
IN
IN
shorted to ground. The LDO uses method (1) and
shorted to supply. No load protection. 33702
is 1.0 V/ms.
is rising, initially LDO will be below the regulation
is falling, LDO will be below the regulation point;
IN
, the Pass FET will attempt to maintain
Methods of Control
IN
IN
IN
is falling faster than LDO, the Pass
. Thus, provided V
= V
IN1
= V
Freescale Semiconductor, Inc.
IN2
For More Information On This Product,
Methods of Control
= 3.3 V
section, page 16.
IN
IN
does not fall
) and the
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2. Single 5.0 V Supply, V
The LDO supplies the core (e.g., 1.8 V nominal) (see
page 16).
Power Up
current and capacitance, and the relative rise times of the V
and V
Power Down
capacitance and the relative fall times of the V
supplies. There are 2 cases:
Shorted Load
3. LDO shorted to supply. No load protection.
1. V
2. LDO rises faster than V
1. LDO falls faster than V
2. V
1. LDO shorted to ground. The V
2. V
3. V
4. V
5. LDO shorted to supply. No load protection.
6. V
V
The switcher V
This condition depends upon the regulator current limit, load
This condition depends upon the regulator load current and
In the case V
the Buck High-Side FET and the LDO external Pass FET,
and will discharge the V
supply.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
IN2
the load capacitor will be discharged rapidly through the
Pass FET to V
control methods (4) and (5) described in the
Control
methods (1) and (2) described in the
section, page 17.
methods (4) and (5) described in the
section, page 17.
methods (1) and (2) described in the
section, page 17.
(5) described in the
(1) and (2) described in the Methods of Control section.
output shorted to ground.
V
protected by current limit and thermal limit.
IN2
OUT
OUT
OUT
IN1
IN2
OUT
OUT
supplies. There are 2 cases:
shorted to ground. This is equivalent to the LDO
shorted to ground. This is equivalent to the switcher
output shorted to ground.
rises faster than LDO. The switcher V
falls faster than LDO. The LDO uses control
shorted to ground. The LDO uses control methods
shorted to supply. No load protection. 33702
section, page 17.
IN1
OUT
= V
IN
.
supplies the microprocessor I/O voltage.
IN2
Methods of Control
the intrinsic operation will turn both
OUT
IN1
OUT
OUT
= V
load capacitor into the V
. The V
. The LDO uses control
IN2
OUT
, or Dual Supply V
OUT
uses methods (4) and
Methods of Control
Methods of Control
Methods of Control
uses control
section, page 17.
IN1
OUT
and V
Methods of
Figure
uses
IN2
IN
IN1
12,
IN1