RP504x Series
600 mA PWM/VFM Step-Down DC/DC Converter with Synchronous Rectifier
NO.EA-259-170620
OUTLINE
The RP504x is a low supply current CMOS-based PWM/VFM step-down DC/DC converter with synchronous
rectifier featuring 600 mA
*1
output current. Internally, a single converter consists of an oscillator, a reference
voltage unit, an error amplifier, a switching control circuit, a mode control circuit (RP504xxx1A/D), a soft-start
circuit, a Latch-type protection circuit, an under voltage lockout (UVLO) circuit a.nd switching transistors.
The RP504x is employing synchronous rectification for improving the efficiency of rectification by replacing
diodes with built-in switching transistors. Using synchronous rectification not only increases circuit performance
but also allows a design to reduce parts count.
Power controlling method can be selected from forced PWM control type or PWM/VFM auto switching control
type by inputting a signal to the MODE pin. In low output current, forced PWM control switches at fixed frequency
rate in order to reduce noise. Likewise, in low output current, PWM/VFM auto switching control automatically
switches from PWM mode to VFM mode in order to achieve high efficiency.
Output voltage is internally fixed type which allows output voltages that range from 0.8 V to 3.3 V in 0.1 V step.
The output voltage accuracy is as high as ±1.5% or ±18 mV.
Protection circuits included in the RP504x are overcurrent protection circuit and latch type protection circuit.
Overcurrent protection circuit supervises the inductor peak current in each switching cycle, and if the current
exceeds the L
X
current limit (I
LXLIM
), it turns off P-channel Tr. Latch type protection circuit latches the built-in driver
to the OFF state and stops the operation of the step-down DC/DC converter if the overcurrent status continues or
V
OUT
continues being the half of the setting voltage for equal or longer than protection delay time (tprot). To cancel
the latch type protection circuit, select the standby mode or the active mode with the CE pin, or drop the power
supply voltage below the UVLO detector threshold.
The RP504x is offered in 6-pin DFN(PLP)1216-6F, 6-pin DFN1616-6B and 5-pin SOT-23-5 packages which
achieve the smallest possible footprint solution on boards where area is limited.
*1
This is an approximate value. The output current is dependent on conditions and external components.
1
RP504x
NO.EA-259-170620
FEATURES
•
Supply Current ...................................................... Typ. 25 µA in VFM mode without any load
•
Standby Current .................................................... Max. 5 µA
•
Input Voltage Range ............................................. 2.3 V to 5.5 V (V
OUT
≥
1.0 V)
•
Output Voltage Range........................................... 0.8 V to 3.3 V in 0.1 V step
•
Output Voltage Accuracy....................................... ±1.5% (V
OUT
≥
1.2 V), ±18 mV (V
OUT
< 1.2 V)
•
Temperature-Drift Coefficient of Output Voltage ... Typ. ±40 ppm/°C
•
Oscillator Frequency ............................................. Typ. 2.25 MHz
•
Oscillator Maximum Duty Cycle ............................ Min. 100%
•
Built-in Driver ON Resistance ............................... Typ. Pch. 0.34
Ω,
Nch. 0.43
Ω
(V
IN
= 3.6 V)
•
UVLO Detector Threshold..................................... Typ. 2.0 V
•
Soft Start Time ...................................................... Typ. 0.15 ms
•
L
X
Current Limit ..................................................... Typ. 900 mA
•
Latch-type Protection Circuit ................................. Typ. 1.5 ms
•
Auto-discharge Function ....................................... Only for RP504xxxxD
•
Power Controlling Method ..................................... forced PWM control or PWM/VFM auto switching control
•
MODE Pin
*1
........................................................... “H”: forced PWM control,
“L”: PWM/VFM auto switching control
•
Package
*1
.............................................................. DFN1616-6B, DFN(PLP)1216-6F, SOT-23-5
*1
DFN(PLP)1216-6F, DFN1616-6B: forced PWM control by pulling MODE pin “H” or PWM/VFM auto switching control by
pulling MODE pin “L”
SOT-23-5: forced PWM control for RP504xxxxC and PWM/VFM auto switching control for RP504xxxxB
APPLICATIONS
•
Power source for battery-powered equipment.
•
Power source for hand-held communication equipment, cameras, VCRs, camcorders.
•
Power source for HDD, portable equipment.
2
RP504x
NO.EA-259-170620
SELECTION GUIDE
The set output voltage, the package type, the MODE control pin function and the auto-discharge
*1
function
are user-selectable options.
Product Name
RP504Kxx1$-E2
RP504Lxx1$-TR
RP504Nxx1$-TR-FE
Package
DFN(PLP)1216-6F
DFN1616-6B
SOT-23-5
Quantity per Reel
5,000 pcs
5,000 pcs
3,000 pcs
Pb Free
Yes
Yes
Yes
Halogen Free
Yes
Yes
Yes
xx: Specify the set output voltage (V
SET
) within the range of 0.8 V(08) to 3.3 V(33) in 0.1 V steps.
Refer to the section of
PACKAGE INFORMATION
for detailed information.
$: Specify the package type, the MODE control pin function and the auto-discharge function.
$
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 Pin Function
MODE Pin
Yes
No
No
Yes
Power Controlling Method
“H”: forced PWM
“L”: PWM/VFM auto switching control
PWM/VFM auto switching control
forced PWM control
“H”: forced PWM control
“L”: PWM/VFM auto switching control
Auto-discharge
Function
No
No
No
Yes
*1
Auto-discharge function quickly lowers the output voltage to 0 V, 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.
0.05 V step is also available as a custom code.
*2
3
RP504x
NO.EA-259-170620
BLOCK DIAGRAMS
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
SOFT
START
UVLO
V
OUT
MODE
GND
RP504xxxxA Block Diagram
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
SOFT
START
UVLO
V
OUT
MODE
GND
RP504xxxxB Block Diagram
4
RP504x
NO.EA-259-170620
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
Lx
VREF
PWM
SWITCHING
CONTROL
SOFT
START
UVLO
V
OUT
MODE
GND
RP504xxxxC Block Diagram
V
IN
CE
CHIP
ENABLE
RAMP
COMPENSATION
CURRENT
FEEDBACK
OSCILLATOR
CURRENT
PROTECTION
SWITCHING
CONTROL
L
X
VREF
PWM
SOFT
START
UVLO
V
OUT
MODE
GND
RP504xxxxD Block Diagram
5
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