RP508K Series
600 mA 6 MHz Synchronous Step-down DC/DC Converter
NO. EA-318-171106
OUTLINE
The RP508K is a low supply current 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 RP508K works as
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 RP508K 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 RP508K 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.
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. 15 µA (VFM Mode with No-load)
•
Standby Current (Istandby) ··································· Typ. 0 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
(1)
This is an approximate value. The output current is dependent on conditions and external components.
1
RP508K
NO. EA-318-171106
•
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
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 steps
(2)
.
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)
(2)
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
RP508K
NO. EA-318-171106
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings
Symbol
V
IN
V
LX
V
CE
V
MODE
V
OUT
I
LX
P
D
Tj
Tstg
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
(1)
(JEDEC STD 51-7 Test Land Pattern )
Junction Temperature Range
Storage Temperature Range
Item
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 125
−55
to 125
Unit
V
V
V
V
V
mA
mW
°C
°C
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
Symbol
V
IN
Ta
Input Voltage
Operating Temperature Range
Item
Rating
2.3 to 5.5
−40
to 85
Unit
V
°C
RECOMMENDED OPERATING CONDITIONS
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.
(1)
Refer to
POWER DISSIPATION
for detailed information.
5
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