MC34717EP Freescale Semiconductor, MC34717EP Datasheet - Page 16

• Manufacturer Part Number: MC34717EP
• Description: IC CONVERTER DDR 26QFN
• Manufacturer: Freescale Semiconductor

Specifications of MC34717EP

• Applications: Converter, DDR
• Voltage - Input: 3 ~ 6 V
• Number Of Outputs: 2
• Voltage - Output: 0.7 ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 26-QFN
• Output Voltage: 0.7 V to 3.6 V
• Output Current: 5 A
• Input Voltage: 3 V to 6 V
• Switching Frequency: 1 MHz
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• No. Of Outputs: 2
• Power Dissipation Pd: 2.03W
• No. Of Pins: 26
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS 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 34717 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
16
34717
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
T
J
V
The 34717 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 34717 checks the status
OUT2
>= 170°C
I
For>=10 ms
OUT2
>=V
>=I
Thermal Shutdown
OVR2
V
LIM2
OUT2
V
V
Channel 2
Over-voltage
OUT2
OUT1
V
V
PG = 1
OUT1
OUT2
<=V
PG = 1
V
=OFF
OUT2
=ON
UVF2
=ON
=ON
Under-voltage
Over-current
TIMEOUT=1
V
V
V
V
Channel 2
OUT2
OUT1
OUT2
T
T
PG = 1
OUT1
V
PG = 1
V
J
IMEOUT
OUT2
<=145°C
OUT2
V
=OFF
=ON
=ON
OUT2
=ON
=>=V
T
Expired
Expired
<=V
IMEOUT
UVR2
OVF2
IN
SD = 0
FUNCTIONAL DEVICE OPERATION
needs to be within its
F
V
V
SW
OUT1
OUT2
I
Figure 5. Operation Modes Diagram
Shutdown
is programmed
OUT2
PG = 1
Short-circuit
T
Expired
TIMEOUT=1
V
= Discharge
= Discharge
V
SD =1
IMEOUT
OUT2
OUT1
PG = 1
>=I
V
OPERATIONAL MODES
OUT2
SHORT2
=OFF
I
=ON
LM1
V
OUT1
F
, I
SW
LM2
V
V
3.0 V<=V
and V
is programmed
OUT1
OUT2
Normal
PG = 0
are programmed
OUT2
= ON
= ON
IN
the SD pin is set to high, the V
the bias currents will be established, so the internal V
signal can be released. The rest of the internal blocks will be
enabled and the buck converter switching frequency and soft
start timing values are determined by reading the FREQ,
ILIM1, and ILIM2 pins. A soft start cycle is then initiated to
ramp up the output of the buck converter. The first channel
uses an internal 0.7 V reference for its error amplifier while
the second channel’s error amplifier uses the voltage on the
VREFIN pin as its reference voltage until V
0.7 V, then the error amplifier defaults to the internal 0.7 V
reference voltage. This method allows the second output to
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
<=6.0 V
t
ss
Short-circuit
TIMEOUT=1
V
Soft start is used to prevent the output voltage from
= 1
V
V
V
OUT1
OUT2
Power Off
PG = 1
I
V
OUT1
OUT2
T
Expired
OUT1
PG = 1
IMEOUT
OUT1
=OFF
=ON
=OFF
=OFF
>=I
SHORT1
V
IN
< 3.0 V
V
Analog Integrated Circuit Device Data
T
Expired
OUT1
IMEOUT
V
T
T
OUT1
J
IMEOUT
<=145°C
OUT
<= V
Under-voltage
Over-current
TIMEOUT=1
V
V
Channel 1
V
V
OUT1
>= V
OUT2
DDI
IN
PG = 1
OUT1
OUT2
PG = 1
V
OVF1
= 0 V. Therefore, the voltage
OUT1
Expired
during the capacitor charge
UVR1
=OFF
=ON
internal supply voltage and
=ON
=ON
Freescale Semiconductor
Thermal Shutdown
Over-voltage
V
V
V
OUT1
V
V
OUT1
OUT2
Channel 1
PG = 1
V
OUT1
OUT2
PG = 1
OUT1
REFIN
<=V
=ON
=ON
=OFF
=ON
V
OUT1
I
For>=10 ms
OUT1
OUT1
is equal to
T
>=V
J
>=I
>=170°C
DDI
LIM1
OVR1
POR