MC34713EP Freescale, MC34713EP Datasheet - Page 13

• Manufacturer Part Number: MC34713EP
• Manufacturer: Freescale

Specifications of MC34713EP

• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Pin Count: 24
• Mounting: Surface Mount
• Package Type: QFN
• Case Length: 4mm
• Screening Level: Industrial
• Lead Free Status / RoHS Status: Compliant

MODES OF OPERATION
Normal Mode
operational. To be in this mode, the V
operating range, Shutdown input is high, and no faults are
present. This mode consumes the most amount of power.
Shutdown Mode
is in a shutdown state and the output is disabled and
discharged. In this mode, the 34713 consumes the least
amount of power since almost all of the internal blocks are
disabled.
START-UP SEQUENCE
of the SD pin. If the device is in a shutdown mode, no block
will power up and the output will not attempt to ramp. Once
the SD pin is released to enable the device, the V
supply voltage and the bias currents are established and the
internal V
Analog Integrated Circuit Device Data
Freescale Semiconductor
The 34713 has two primary modes of operation:
In normal mode, all functions and outputs are fully
In this mode, activated by pulling the SD pin low, the chip
When power is first applied, the 34713 checks the status
V
OUT
>V
V
OUT
OV
DDI
<V
POR signal is also released. The rest of the
Over-voltage
UV
V
V
PG = 1
OUT
REF
SD = 0
=ON
=ON
Under-voltage
V
V
OUT
REF
PG = 1
V
V
OUT
REF
=ON
=ON
Shutdown
V
PG = 1
V
= Discharge
= Discharge
OUT
OUT
>V
<V
UV
OV
SD = 1
IN
FUNCTIONAL DEVICE OPERATION
needs to be within its
Figure 5. Operation Modes Diagram
3.0 V<=V
T
V
J
IN
>= 170°C
DDI
< 3.0 V
OPERATIONAL MODES
internal
IN
<=6.0 V
Thermal Shutdown
V
Power Off
V
V
V
OUT
REF
Normal
V
PG = 1
PG = 0
V
REF
TT
OUT
REF
PG = 1
= ON
=OFF
=OFF
=ON
=OFF
=OFF
T
T
J
IMEOUT
<=145°C
internal blocks will be enabled and the buck converter
switching frequency and soft start values are determined by
reading the FREQ and ILIM pins respectively. A soft start
cycle is then initiated to ramp up the output of the buck
converter. The buck converter error amplifier uses the
voltage on the VREFIN pin as its reference voltage until
V
the internal 0.7 V reference voltage. This method helps
achieve multiple tracking configurations as will be explained
later in this document.
overshooting during startup. At initial startup, the output
capacitor is at zero volts; V
across the inductor will be PV
phase which will create a very sharp di/dt ramp. Allowing the
inductor current to rise too high can result in a large
difference between the charging current and the actual load
current that can result in an undesired voltage spike once the
capacitor is fully charged. The soft start is active each time
the IC goes out of standby or shutdown mode, power is
recycled, or after a fault retry.
enabled, no faults have occurred, and the output voltage has
reached its regulation point, the 34713 pulls the power good
REFIN
Soft start is used to prevent the output voltage from
After a successful start-up cycle where the device is
Expired
is equal to 0.7 V, then the error amplifier defaults to
T
Expired
T
Expired
IMEOUT
IMEOUT
FUNCTIONAL DEVICE OPERATION
OUT
Over-current
V
V
OUT
IN
REF
PG = 1
= 0 V. Therefore, the voltage
during the capacitor charge
=OFF
=ON
OPERATIONAL MODES
Short-circuit
V
V
OUT
REF
PG = 1
=OFF
=OFF
I
I
For>=10 ms
OUT
OUT1
>=I
>=I
SHORT
LIM1
34713
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