RP508x Series
600 mA 6 MHz Synchronous Step-down DC/DC Converter
NO. EA-318-130828
OUTLINE
The RP508x 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, a soft-start circuit, an
under-voltage lockout (UVLO) circuit, an over current protection circuit, a thermal shutdown circuit and switching
transistors.
By the adoption of the synchronous rectification circuit with built-in switching transistors, the RP508x works as
super efficient step-down DC/DC converter, without connecting external diodes. 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 RP508x are over current protection circuit and thermal shutdown circuit. Over
current 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. Thermal shutdown circuit detects overheating of the converter
if the output pin is shorted to the ground pin (GND) etc. and stops the converter operation to protect it from
damage if the junction temperature exceeds the specified temperature.
The RP508x is offered in a small and thin 6-pin DFN(PLP)1212-6F package which achieves the smallest
possible footprint solution on boards where area is limited.
For an input capacitor (C
IN
) and an output capacitor (C
OUT
), the smaller sized 0402/1005 (inch/mm) capacitor
can be used. For an inductor (L), the smaller sized 0603/1608 or 1005/2012 (inch/mm) inductor can be used.
*1
This is an approximate value. The output current is dependent on conditions and external components.
1
RP508x
NO. EA-318-130828
FEATURES
•
Input Voltage Range (V
IN
)·············································· 2.3 V to 5.5 V (Absolute Maximum Ratings: 6.5 V)
•
Output Voltage Range (V
OUT
) ········································ 0.8 V to 3.3 V (Adjustable in 0.1 V steps)
•
Supply Current (I
DD2
) ····················································· Typ. 18 µA (VFM Mode with No-load)
•
Standby Current (Istandby) ··········································· Max. 5 µA
•
Output Voltage Temperature Coefficient (∆V
OUT
/Ta) ······· Typ. ±100 ppm/°C
•
Oscillator Frequency (fosc) ··········································· Typ. 6.0 MHz
•
Maximum Duty Cycle (Maxduty) ··································· 100%
•
Built-in Driver ON Resistance (R
ONP
, R
ONN
)··················· Typ. Pch. 0.33
Ω,
Nch. 0.24
Ω
(V
IN
= 3.6 V)
•
UVLO Detector Threshold (V
UVLO01
) ······························ Typ. 2.0 V
•
Soft-start Time (tstart)···················································· Typ. 90 µs
•
L
X
Current Limit Circuit (I
LXLIM
)······································· Typ. 1.1 A
•
Output Voltage Accuracy ··············································· ±1.5% (V
OUT
≥
1.2 V) or
±18
mV (V
OUT
< 1.2 V)
•
Package
····································································· DFN(PLP)1212-6F
APPLICATIONS
•
Cellular Phones
•
Smartphones
•
Digital Still Camera
•
Notebook PCs, PDA’s
•
Li-ion Battery-used Equipment
2
RP508x
NO. EA-318-130828
BLOCK DIAGRAM
V
IN
UVLO
Thermal
Protection
Soft Start
Vref
Clock
Generator
Delay
Control
Current
Detector
Delay
Switching
Control
L
X
MODE
CE
Chip
Enable
Mode
Control
OSC
V
OUT
+
RIPPLE
Control
GND
RP508xxx1A Block Diagram
V
IN
UVLO
Thermal
Protection
Soft Start
Vref
Clock
Generator
Delay
Control
Current
Detector
Delay
Switching
Control
L
X
MODE
CE
Chip
Enable
Mode
Control
OSC
V
OUT
+
RIPPLE
Control
GND
RP508xxx1B Block Diagram
3
RP508x
NO. EA-318-130828
SELECTION GUIDE
The set output voltage and the auto discharge
*1
function are user-selectable options.
Selection Guide
Product Name
RP508Kxx1$-TR
Package
DFN(PLP)1212-6F
Quantity per Reel
5,000 pcs
Pb Free
Yes
Halogen Free
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
*2
steps.
If the set output voltage includes the 3rd digit, indicate the digit of 0.01.
(1.05 V, 1.25 V, 1.35 V)
Ex. If the set output voltage is 1.05 V: RP508K101$5
If the set output voltage is 1.25 V: RP508K121$5
If the set output voltage is 1.35 V: RP508K131$5
$: Specify the auto-discharge option.
A: Fixed output voltage type
B: Fixed output voltage type, auto-discharge function in shutdown mode
*1
Auto-discharge function quickly lowers the output voltage to 0 V, when the chip enable signal is switched from the
0.05 V step is also available as a custom code.
active mode to the standby mode, by releasing the electrical charge accumulated in the external capacitor.
*2
PIN DESCRIPTION
Top View
6
5
4
Bottom View
4
5
6
1
2
3
3
2
1
DFN(PLP)1212-6F Pin Configurations
Pin Description
Pin No.
Symbol
1
2
3
4
5
6
V
OUT
MODE
CE
V
IN
L
X
GND
Pin Description
Output Pin
Mode Control Pin
(“H” forced PWM control, “L” PWM/VFM auto switching control)
Chip Enable Pin ("H" active)
Input Pin
L
X
Switching Pin
Ground Pin
4
RP508x
NO. EA-318-130828
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings
Symbol
V
IN
V
LX
V
CE
V
MODE
V
OUT
I
LX
P
D
Ta
Tstg
T
Item
V
IN
Input Voltage
L
X
Pin Voltage
CE Pin Input Voltage
MODE Pin Input Voltage
V
OUT
Pin Voltage
L
X
Pin Output Current
Power Dissipation (JEDEC STD 51-7 Test Land Pattern )*
1
Operating Temperature Range
Storage Temperature Range
Rating
−0.3
to 6.5
−0.3
to V
IN
+0.3
−0.3
to 6.5
−0.3
to 6.5
−0.3
to 6.5
1300
666
−40
to 85
−55
to 125
Unit
V
V
V
V
V
mA
mW
°C
°C
*1
Refer to the section of
PACKAGE INFORMATION
for detailed 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 are 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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