RP504x SERIES
600mA Step-down DC/DC Converter with Synchronous Rectifier
NO.EA-259-130520
OUTLINE
The RP504x Series are low supply current CMOS-based 600mA step-down DC/DC Converters with
synchronous rectifier. Each of these ICs consists of an oscillator, a reference voltage unit, an error amplifier, a
switching control circuit, a mode control circuit(Ver.A, D), a soft-start circuit, a "latch type" protection circuit, an
under voltage lockout (UVLO) circuit, and switching transistors. A low ripple, high efficiency synchronous rectifier
step-down DC/DC converter can be easily composed of this IC with only an inductor and capacitors. Since
packages are SOT-23-5, DFN1616-6B, DFN(PLP)1216-6F, high density mounting on boards is possible.
As protection circuits, the RP504x Series contain a current limit circuit which limits the Lx peak current in each
clock cycle, and a latch type protection circuit which latches the built-in driver to the OFF state if the load current
exceeds the limit value or the output short continues for a specified time (the protection delay time). The latch
protective circuit can be released by once putting the IC into the standby mode with the CE pin and then into the
active mode, or, by turning the power off and back on. Setting the supply voltage lower than the UVLO detector
threshold can also release the latch protective circuit.
In terms of the output voltage, since the feedback resistances are built-in, the voltage is fixed internally. 0.1V
step output can be set by laser-trim and
1.5%
or
18mV
tolerance depending on the output voltage is
guaranteed. By inputting a signal to a MODE pin, the RP504x Series can be switched between PWM/VFM auto
switching control and Forced PWM control. PWM/VFM auto switching control switches to high-efficiency VFM
mode in low output current. Forced PWM control switches to fixed-frequency Forced PWM mode for reducing
noise in low output current.
)This
is an approximate value, because output current depends on conditions and external parts.
FEATURES
Supply Current ...................................................... Typ. 25A(at VFM mode, at no load)
Standby Current .................................................... Max. 5A
Input Voltage Range ............................................. 2.3V to 5.5V (V
OUT
≧1.0V)
Output Voltage Range........................................... 0.8V to 3.3V (With a 0.1V step)
Output Voltage Accuracy.......................................
1.5%
(V
OUT
1.2V), 18mV
(V
OUT
<1.2V)
Temperature-Drift Coefficient of Output Voltage ... Typ.
40ppm/C
Oscillator Frequency ............................................. Typ. 2.25MHz
Oscillator Maximum Duty Cycle ............................ Min. 100%
Built-in Driver ON Resistance ............................... Typ. Pch. 0.34Ω、Nch. 0.43Ω(V
IN
=3.6V)
UVLO Detector Threshold..................................... Typ. 2.0V
Soft Start Time....................................................... Typ. 0.15ms
L
X
Current Limit ..................................................... Typ. 900mA
Latch type Protection Circuit ................................. Typ. 1.5ms
Auto discharge function ........................................ Only for D Version
Two choices of Switching Mode............................ DFN1616-6B and DFN(PLP)1216-6F are available in
adjustable switching control options from PWM/VFM auto switching type or Forced PWM type by using
MODE pin. SOT-23-5 is available in fixed switching control options: PWM/VFM auto switching type for B
version or Forced PWM type for C version.
Packages .............................................................. SOT-23-5, DFN1616-6B, DFN(PLP)1216-6F
1
RP504x
APPLICATIONS
Power source for battery-powered equipment.
Power source for hand-held communication equipment, cameras, VCRs, camcorders.
Power source for HDD, portable equipment.
BLOCK DIAGRAMS
RP504xxxxA
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
UVLO
SOFT
START
V
OUT
MODE
GND
RP504xxxxB
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
UVLO
SOFT
START
V
OUT
MODE
GND
2
RP504x
RP504xxxxC
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
UVLO
SOFT
START
V
OUT
MODE
GND
RP504xxxxD
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
SWITCHING
CONTROL
UVLO
L
X
VREF
PWM
SOFT
START
V
OUT
MODE
GND
3
RP504x
SELECTION GUIDE
In the RP504x Series, output voltage, MODE control, auto discharge function, and package for the ICs are
selectable at the user’s request.
Product Name
RP504Nxx1$-TR-FE
RP504Lxx1$-TR
RP504Kxx1$-E2
Package
SOT-23-5
DFN1616-6B
DFN(PLP)1216-6F
Quantity per Reel
3,000 pcs
5,000 pcs
5,000 pcs
Pb Free
Yes
Yes
Yes
Halogen Free
Yes
Yes
Yes
xx : The output voltage can be designated in the range from 0.8V(08) to 3.3V(33) in 0.1V steps
1
.
Designation is possible in the range from 0.8V to 3.3V with a step of 0.1V
(Refer to the marking information)
$ : Designation of mask option
Symbol
A
B
C
D
Package
DFN1616-6B
DFN(PLP)1216-6F
SOT-23-5
SOT-23-5
DFN1616-6B
DFN(PLP)1216-6F
Mode Control
Yes
(“H” forced PWM,
“L” PWM/VFM automatic shift)
No
(PWM/VFM automatic shift)
No
(forced PWM)
Yes
(“H” forced PWM,
“L” PWM/VFM automatic shift)
Auto discharge function
No
No
No
Yes
Auto-discharge function quickly lowers the output voltage to 0V, when the chip enable signal is switched from the active
mode to the standby mode, by releasing the electrical charge accumulated in the external capacitor.
1)
0.05V step is also available as a custom code.
PIN CONFIGURATIONS
SOT-23-5
Top View
5
4
6
5
DFN1616-6B
Top View
4
DFN(PLP)1216-6F
Top View
6
5
4
Bottom View
4
5
6
Bottom View
4
5
6
(mark side)
1
2
3
3
2
1
1
2
3
3
2
1
1
2
3
4
RP504x
PIN DESCRIPTIONS
RP504Nxx1B, RP504Nxx1C : SOT-23-5
Pin No.
1
2
3
4
5
Symbol
V
OUT
GND
L
X
V
IN
CE
Output Pin
Ground Pin
L
X
Switching Pin
Input Pin
Chip Enable Pin ("H" Active)
Description
RP504Lxx1A, RP504Lxx1D : DFN1616-6B
Pin No.
1
2
3
4
5
6
Symbol
CE
MODE
V
IN
L
X
GND
V
OUT
Description
Chip Enable Pin ("H" Active)
Mode Control Pin (“H” forced PWM, “L” PWM/VFM automatic shift)
Input Pin
L
X
Switching Pin
Ground Pin
Output Pin
)
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.
RP504Kxx1A, RP504Kxx1D : DFN(PLP)1216-6F
Pin No.
1
2
3
4
5
6
Symbol
V
IN
MODE
CE
V
OUT
GND
L
X
Input Pin
Mode Control Pin (“H” forced PWM, “L” PWM/VFM automatic shift)
Chip Enable Pin ("H" Active)
Output Pin
Ground Pin
L
X
Switching Pin
Description
5
