RP501K SERIES
1A Step-down DC/DC Converters with synchronous rectifier
NO.EA-199-111124
OUTLINE
The RP501K Series are CMOS-based step-down DC/DC Converters with synchronous rectifier.
Each of these ICs consists of an oscillator, a switching control circuit, a reference voltage unit, an error
amplifier, a soft-start circuit, protection circuits, UVLO circuit, switching transistors. A low ripple, high efficiency
step-down DC/DC converter can be easily composed of this IC with only an inductor and capacitors. In terms of
the output voltage, since the feedback resistances are built-in, the voltage is fixed internally. 50mV
(custom-made) step output can be set by laser-trim and
±1.5%
or
±24mV
tolerance depending on the output
voltage is guaranteed.
Mode alternative circuit works automatically for improving the efficiency. Considering fixed noise frequency,
PWM fixed control type is also available. As protection circuits, the current limit circuit which limits peak current
of L
X
at each clock cycle, and the latch type protection circuit which works if the term of the over-current condition
keeps on a certain time exist. The latch-type protection circuit works to latch an internal driver with keeping it
disable. To release the condition of the protection, after disabling this IC with a chip enable circuit, enable it again,
or restart this IC with power-on or make the supply voltage at UVLO detector threshold level or lower than UVLO.
Since the package is DFN(PLP)2527-10, high density mounting on boards is possible.
FEATURES
Input Voltage Range ..............................................2.5V to 5.5V
Output Voltage .......................................................1.0V to 3.3V
High Accuracy Output Voltage ...............................±1.5% (V
OUT
≥1.6V)
±24mV (V
OUT
<1.6V)
Oscillator Frequency..............................................Typ. 2.25MHz
Built-in Soft start Function......................................Max.0.2ms
Built-in Peak current limit .......................................Typ.1.5A
Built-in UVLO Function ..........................................Typ. 2.2V
Switching Mode can be controlled by Mode pin ....Automatic PWM/VFM mode change / PWM fixed
Package .................................................................DFN(PLP)2527-10
APPLICATIONS
Power source for portable equipment such as cellular, PDA, DSC, Notebook PC
Power source for HDD, WLA N, Car accessories
Power source for Li-ion battery-used equipment
1
RP501K
BLOCK DIAGRAM
RP501Kxx1A
A
IN
V
CE
CHIP
ENABLE
SLOPE
COMPENSATION
CURRENT
FEEDBACK
PV
IN
OSCILLATOR
CURRENT
PROTECTION
SWITCHING
CONTROL
L
X
VREF
PWM/VFM
CONTROL
UVLO
SOFT
START
V
OUT
MODE
AGND
PGND
TEST1
TEST2
RP501Kxx1B
A
IN
V
CE
CHIP
ENABLE
SLOPE
COMPENSATION
CURRENT
FEEDBACK
PV
IN
OSCILLATOR
CURRENT
PROTECTION
SWITCHING
CONTROL
L
X
VREF
PWM/VFM
CONTROL
UVLO
SOFT
START
V
OUT
MODE
AGND
PGND
TEST1
Mode="H": PWM/VFM alternative , Mode="L": PWM fix control
Test Pin must be connected to GND.
TEST2
2
RP501K
Selection Guide
In the RP501K series, output voltage and version can be designated with user's request.
Part number can be designated as follows:
Product Name
RP501Kxx1∗-TR
Package
DFN(PLP)2527-10
Quantity per Reel
5,000 pcs
Pb Free
Yes
Halogen Free
Yes
xx : Designation of output voltage(V
OUT
):
Designation is possible in the range from 1.0V to 3.3V with a step of 0.1V
∗
: Designation of Active Type
(A) without auto-discharge function
(B) with auto-discharge function
When the mode is into standby with CE signal, auto-discharge transistor turns on, and it makes the turn-off speed
faster then normal type.
* Stepwise setting with 0.05V is possible by custom-made.
3
RP501K
PIN CONFIGURATION
DFN(PLP)2527-10
TOP VIEW
10
9
8
7
6
1
BOTTOM VIEW
2
3
4
5
1
2
3
4
5
10
9
8
7
6
PIN DESCRIPTIONS
Pin No.
1
2
3
4
5
6
7
8
9
10
Symbol
CE
TEST1
AGND
PGND
L
X
PV
IN
TEST2
MODE
AV
IN
V
OUT
Chip Enable Pin (“H” Active)
Test Pin 1 (Connect this pin to the GND)
Ground Pin
Ground Pin
Switch Output Pin
Input Pin
Test Pin 2 (Connect this pin to the GND)
Mode Control Pin
Input Pin
Output Pin
Pin Description
* Tab is GND level. (They are connected to the reverse side of this IC.) The tab is better to be connected to the GND, but
leaving it open is also acceptable.
* All V
IN
terminals must be connected.
* All GND terminals must be connected.
4
RP501K
ABSOLUTE MAXIMUM RATINGS
Symbol
AV
IN
PV
IN
V
LX
V
CE
V
MODE
V
OUT
I
LX
P
D
T
a
T
stg
Item
AV
IN
Supply Voltage
PV
IN
Supply Voltage
L
X
Pin Voltage
CE Pin Input Voltage
MODE Pin Input Voltage
V
OUT
Pin Voltage
L
X
Pin Output Current
Power Dissipation
*
Operating Temp. Range
Storage Temp. Range
Rating
-0.3 to 6.5
-0.3 to 6.5
-0.3 to A/PV
IN
+0.3
-0.3 to 6.5
-0.3 to 6.5
-0.3 to 6.5
1.5
910
-40 to 85
-55 to 125
(
AGND=PGND=0V)
Unit
V
V
V
V
V
V
A
mW
°C
°C
*)
For Power Dissipation, please refer to PACKAGE INFORMATION.
ABSOLUTE MAXIMUM RATINGS
Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause the
permanent damages and may degrade the life time and safety for both device and system using the device
in the field. The functional operation at or over these absolute maximum ratings is not assured.
RECOMMENDED OPERATING CONDITIONS (ELECTRICAL CHARACTERISTICS)
All of electronic equipment should be designed that the mounted semiconductor devices operate within the
recommended operating conditions. The semiconductor devices cannot operate normally over the
recommended operating conditions, even if when they are used over such conditions by momentary
electronic noise or surge. And the semiconductor devices may receive serious damage when they continue
to operate over the recommended operating conditions.
5
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