PWM/VFM STEP-DOWN DC/DC CONVERTER
WITH SYNCHRONOUS RECTIFIER
R1230D SERIES
NO. EA-085-0305
OUTLINE
The R1230D Series are CMOS-based PWM step-down DC/DC Converters with synchronous rectifier, low supply
current.
Each of these ICs 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/VFM alternative
circuit, a chip enable circuit, and a driver transistor. A low ripple, 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. (As for
R1230D001G/H types, divider resistors are also necessary.) In terms of Output Voltage, it is fixed internally in the
R1230Dxx1E/F types. While in the R1230D001G/H types, Output Voltage is adjustable with external divider resistors.
PWM/VFM alternative circuit is active with Mode Pin of the R1230D Series. Thus, when the load current is small,
the operation can be switching into the VFM operation from PWM operation by the logic of MODE pin and the effi-
ciency at small load current can be improved. As protection circuits, Current Limit circuit which limits peak current of
Lx at each clock cycle, and Latch type protection circuit which works if the term of Over-current condition keeps on a
certain time in PWM mode exist. Latch-type protection circuit works to latch an internal driver with keeping it disable.
To release the condition of 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 0.35Ω, N-channel 0.45Ω (at V
IN
=3V)
•
Built-in Soft-start Function (Typ. 1.5ms), and Latch-type Protection Function (Delay Time; Typ. 1.5ms)
•
Two choices of Oscillator Frequency...........................500kHz, 800kHz
•
PWM/VFM alternative with MODE pin .....................PWM operation; MODE pin at "L",
VFM operation; MODE pin at "H"
•
High Efficiency .............................................................Typ. 90%
•
Output Voltage..............................................................Stepwise Setting with a step of 0.1V in the range of 1.2V ~
3.3V (xx1E/F Type) or adjustable in the range of 0.8V to V
IN
(001G/H Type)
•
High Accuracy Output Voltage ....................................±2.0% (xx1E/F Type)
•
Package .........................................................................SON8 (Max height 0.9mm, thin type)
1
R1230D
APPLICATIONS
•
Power source for portable equipment.
BLOCK DIAGRAM
•
R1230Dxx1E/F
3
V
IN
V
DD
6
MODE
“L” PWM “H” VFM
1
PWM/VFM
CONTROL
OUTPUT
CONTROL
Current Protection
UVLO
OSC
Phase
Compensation
5
V
OUT
8
2
PGND
•
R1230D001G/H
3
V
IN
V
DD
1
PWM/VFM
CONTROL
OUTPUT
CONTROL
Current Protection
UVLO
8
2
PGND
2
-
-
+
L
X
-
-
+
7
AGND
6
7
AGND
L
X
-
+
Vref
CE
“H” Active
Soft Start
Chip Enable
4
CE
MODE
“L” PWM “H” VFM
OSC
Phase
Compensation
5
V
FB
-
+
Vref
Soft Start
Chip Enable
“H” Active
4
CE
R1230D
SELECTION GUIDE
In the R1230D Series, the output voltage, the oscillator frequency, and the taping type for the ICs can be selected at
the user's request.
The selection can be made by designating the part number as shown below;
R1230Dxxxx-xx
↑ ↑↑ ↑
a bc d
Code
Setting Output Voltage(V
OUT
):
a
b
Stepwise setting with a step of 0.1V in the range of 1.2V to 3.3V is possible for E/F version.
"00" is for Output Voltage Adjustable G/H version (0.8V ~ )
1 : fixed
Designation of Optional Function
E : 500kHz, Fixed Output Voltage
c
F : 800kHz, Fixed Output Voltage
G : 500kHz, Adjustable Output Voltage
H : 800kHz, Adjustable Output Voltage
d
Designation of Taping Type; (Refer to Taping Specification)
"TR" is prescribed as a standard.
Contents
←
Part Number
PIN CONFIGURATION
SON-8
8 7 6 5
1
2
3
4
3
R1230D
PIN DESCRIPTION
Pin No.
1
2
3
4
5
6
7
8
Symbol
V
IN
PGND
V
DD
CE
V
OUT
/V
FB
MODE
AGND
L
X
Voltage Supply Pin
Ground Pin
Voltage Supply Pin
Chip Enable Pin (active with "H")
Output/Feedback Pin
Mode changer Pin (PWM mode at "L", VFM mode at "H".)
Ground Pin
L
X
Pin
Description
ABSOLUTE MAXIMUM RATINGS
AGND=PGND=0V
Symbol
V
IN
V
DD
V
LX
V
CE
V
MODE
V
FB
I
LX
P
D
Topt
Tstg
Item
V
IN
Supply Voltage
V
DD
Pin Voltage
L
X
Pin Voltage
CE Pin Input Voltage
MODE Pin Input Voltage
V
FB
Pin Input Voltage
LX Pin Output Current
Power Dissipation
Operating Temperature Range
Storage Temperature Range
Rating
6.5
6.5
-0.3 ~ V
IN
+0.3
-0.3 ~ V
IN
+0.3
-0.3 ~ V
IN
+0.3
-0.3 ~ V
IN
+0.3
-0.8
250
-40 ~ +85
-55 ~ +125
Unit
V
V
V
V
V
V
A
mW
°C
°C
4
R1230D
ELECTRICAL CHARACTERISTICS
•
R1230Dxx1E/F
Topt=25°C
Symbol
V
IN
V
OUT
∆V
OUT
/
∆T
fosc
fosc
I
DD
I
DD
Istb
R
ONP
R
ONN
I
LX
leak
I
VOUT
I
CE
V
CEH
V
CEL
Maxdty
V
LX
Item
Operating Input Voltage
Step-down Output Voltage
Step-down Output Voltage Tem-
perature Coefficient
Oscillator Frequency (xx1E)
Oscillator Frequency (xx1F)
Supply Current (xx1E)
Supply Current (xx1F)
Standby Current
ON Resistance of Pch Transistor
ON Resistance of Nch Transistor
L
X
Leakage Current
V
OUT
Leakage Current
CE Input Current
CE "H" Input Voltage
CE "L" Input Voltage
Oscillator Maximum Duty Cycle
L
X
Limit Voltage
,
V
IN
=V
CE
=V
SET
+1.5V
V
MODE
=0V I
OUT
=10mA
,
-40°C
≤
Topt
≤
85°C
V
IN
=V
CE
=V
SET
+1.5V
V
IN
=V
CE
=V
SET
+1.5V
,
V
IN
=V
CE
=V
SET
+1.5V
V
OUT
=V
MODE
=0V
,
V
IN
=V
CE
=V
SET
+1.5V
V
OUT
=V
MODE
=0V
,
V
IN
=5.5V V
CE
=V
OUT
=0V
V
IN
=5.0V
V
IN
=5.0V
,
,
V
IN
=5.5V V
CE
=0V
V
LX
=0V/5.5V
,
,
V
IN
=5.5V V
CE
=0V
V
LX
=0V/5.5V
,
,
V
IN
=5.5V V
MODE
=0V
V
CE
=5.5V/0V
V
IN
=5.5V V
OUT
=0V
,
V
IN
=2.4V V
OUT
=0V
,
V
MODE
=0V
,
V
MODE
=V
OUT
=0V
V
IN
=V
CE
=3.0V
100
V
IN
-
0.15
V
IN
-
0.35
V
IN
-
0.55
0.20
0.20
-0.1
-0.1
-0.1
1.5
0.3
425
680
Conditions
Min.
2.4
Typ.×
0.980
V
SET
±150
500
800
230
250
0
0.35
0.45
0.0
0.0
0.0
575
920
300
350
5
0.60
0.70
0.1
0.1
0.1
Typ.
Max.
5.5
Typ.×
1.020
Unit
V
V
ppm/
°C
kHz
kHz
µA
µA
µA
Ω
Ω
µA
µA
µA
V
V
%
V
5
PCB设计
