R5220D SERIES
PWM Step-down DC/DC Converter with Synchronous Rectifier and LDO mode
NO.EA-121-0603
OUTLINE
The R5220D Series are CMOS-based PWM step-down DC/DC Converters with synchronous rectifier, low
supply current and LDO mode.
DC/DC converter of the R5220D consists of an oscillator, a PWM control circuit, a reference voltage unit, an
error amplifier, a soft-start circuit, protection circuits, a protection against miss operation under low voltage
(UVLO), PWM-DC to DC converter / LDO alternative circuit, a chip enable circuit, and a driver transistor. A high
efficiency step-down DC/DC converter can be easily composed of this IC with only a few kinds of external
components, or an inductor and capacitors.
LDO of the R5220D consists of a vortage reference unit, an error amplifier, resistors for voltage setting, output
current limit circuit, a driver transistor, and so on. The output voltage is fixed internally in the R5220D. The output
voltage of the DC/DC converter and the LDO can be set independently.
PWM step-down DC/DC converter / LDO alternative circuit is active with Mode Pin of the R5220D Series.
Thus, when the load current is small, the operation can be switching into the LDO operation from PWM operation
by the logic of MODE pin and the consumption current of the IC itself will be small at light load current. As
protection circuits, the current limit circuit which limits peak current of Lx 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 in PWM mode.
Latch-type protection circuit works to latch an internal driver with keeping it disable. To release the protection,
after disable 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.
FEATURES
Built-in Driver ON Resistance ......................................... P-channel 0.5Ω, N-channel 0.5Ω (at V
IN
=3.6V)
Input Voltage ................................................................... 2.8V to 5.5V
Built-in Soft-start Function (Typ. 0.2ms), and Latch-type Protection Function (Delay Time; Typ. 3.0ms)
Low Supply Current ........................................................ Typ. 5µA(LDO)
Standby Current .............................................................. Typ. 0.1µA
Output Current ................................................................ Min. 400mA(DC/DC), Min. 50mA(LDO)
Oscillator Frequency ....................................................... Typ. 1.2MHz
PWM/LDO alternative with MODE pin
Absolute Input Maximum Rating ..................................... 6.5V
Output Voltage ................................................................ Stepwise Setting with a step of 0.1V in the range of
1.0V to 3.3V
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Package .......................................................................... SON-6 (Maximum height 0.85mm, thin type)
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APPLICATIONS
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Power source for portable equipment such as DSC, DVC, and communication equipment.
1
R5220D
BLOCK DIAGRAM
V
IN
OSC
OUTPUT
CONTROL
Vref
Current Limit
Soft
Start
L
X
MODE
∗
1
CE
V
OUT
Vref
Current Limit
GND
*1 R5220DxxxA: DCDC mode: Mode pin= “H”, VR mode: Mode pin= “L”
R5220DxxxB: DCDC mode: Mode pin= “L”, VR mode: Mode pin= “H”
SELECTION GUIDE
In the R5220D Series, the output voltage, the version, and the taping type for the ICs can be selected at the
user's request.
The selection can be made with designating the part number as shown below;
R5220Dxxxx-xx
↑ ↑↑ ↑
a bc d
Code
a
b
←Part
Number
Contents
Setting Output Voltage (V
OUT
) or alphanumeric custom code.
Setting Output Voltage
1: standard (a: output voltage; DC/DC output voltage
=
LDO output voltage
2: custom code (a: custom code; DC/DC output voltage
≠
LDO output voltage
Designation of chip enable and Mode pin polarities
A: CE; "H" active, Mode pin; "H"=DC/DC converter mode, "L"=LDO Mode
B: CE; “H” active, Mode pin; “L”=DC/DC converter mode, “H”=LDO Mode
Designation of Taping Type; (Refer to Taping Specification)"TR" is prescribed as a standard.
c
d
2
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