R1232D SERIES
PWM STEP-DOWN DC/DC CONVERTER WITH SYNCHRONOUS RECTIFIER
NO.EA-129-130510
OUTLINE
The R1232D Series are CMOS-based PWM step-down DC/DC converters with synchronous rectifier, low
supply current. As an output capacitor, a 10μF or more ceramic capacitor can be used with the R1232D.
Each of these ICs consists of an oscillator, a PWM control circuit, a voltage reference unit, an error amplifier, a
soft-start circuit, protection circuits, a protection against miss operation under low voltage (UVLO), a chip enable
circuit, a synchronous rectifier, Nch. driver transistor, and so on. 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 R1232D001x type, divider resistors are also necessary.) In terms of the output voltage, it is
fixed internally in the R1232Dxx1x types. While in the R1232D001x types, the output voltage is adjustable with
external divider resistors.
As protection circuits, current limit circuit which limits peak current of L
X
at each clock cycle, and latch type
protection circuit exist. The latch protection works if the term of the over-current condition keeps on a certain time.
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
•
Two choices of Oscillator Frequency ............................ 1MHz, 2.25MHz
(Small inductors can be used. 4.7μH for 1MHz/2.2μH for 2.25MHz)
•
Built-in Driver ON Resistance ....................................... P-channel 0.2Ω (at V
IN
=5.0V)
•
Built-in Soft-start Function............................................. Typ. 1.0ms (fosc=1MHz type)
•
Output Voltage .............................................................. 0.9V to 3.3V (R1232Dxx1x Type)
0.8V to V
IN
(R1232D001x Type)
•
High Accuracy Output Voltage ......................................±2.0%
•
Built-in Current Limit Circuit .......................................... Typ. 1.4A
•
Package ........................................................................SON-8 (t=0.9mm)
APPLICATIONS
•
Power source for portable equipment such as PDA, DSC, Notebook PC.
•
Power source for HDD
1
R1232D
BLOCK DIAGRAMS
R1232Dxx1A/B
V
DD
3
V
IN
2
Current Limit
Slope
Compensation
Phase
Compensation
Q
R
S
PWM
Comparator
Vref
Error
Amplifer
Soft Start
AGND
7
5
V
OUT
L
X
8
Output
Contorol
Oscillator
4
CE
“H” Active
TEST Circuit
UVLO
Chip Enable
1
PGND
6
TEST
GND Fixed
R1232D001C/D
V
DD
3
V
IN
2
Current Limit
Slope
Compensation
Phase
Compensation
Q
R
S
PWM
Comparator
Error
Amplifer
Soft Start
Vref
AGND
7
5
V
FB
L
X
8
Output
Contorol
Oscillator
4
CE
“H” Active
TEST Circuit
UVLO
Chip Enable
1
PGND
6
TEST
GND Fixed
2
R1232D
SELECTION GUIDE
In the R1232D Series, the output voltage, the oscillator frequency and the output voltage adjustment for the
ICs can be selected at the user’s request.
Product Name
R1232Dxx1∗-TR-FE
Package
SON-8
Quantity per Reel
3,000 pcs
Pb Free
Yes
Halogen Free
Yes
xx : The output voltage can be designated in the range from 0.9 V(09) to 3.3V(33) in 0.1V steps.
(For externally adjustable output voltage type, (00).)
∗
: The oscillator frequency and the output voltage adjustment are options as follows.
Code
A
B
C
D
Oscillator frequency
1MHz
2.25MHz
1MHz
2.25MHz
Output voltage
adjustment
No
No
Yes
Yes
3
R1232D
PIN CONFIGURATION
SON-8
Top View
8
7
6
5
Bottom View
5 6
7
8
∗
∗
∗
1
2
3
4
4 3
2
1
PIN DESCRIPTIONS
Pin No
1
2
3
4
5
6
7
8
Symbol
PGND
V
IN
V
DD
CE
V
OUT
/V
FB
TEST
AGND
L
X
Ground Pin
Voltage Supply Pin
Voltage Supply Pin
Chip Enable Pin (active with "H")
Output/Feedback Pin
Test Pin (Forced to the GND level.)
Ground Pin
L
X
Switching Pin (CMOS Output)
Pin Description
* Tab is GND level. (They are connected to the reverse side of this IC.) The tab is better to be connected to the GND, but
leaving it open is also acceptable.
4
R1232D
ABSOLUTE MAXIMUM RATINGS
Symbol
V
IN
V
DD
V
LX
V
CE
V
TEST
V
OUT
/
V
FB
I
LX
P
D
Ta
Tstg
V
IN
Supply Voltage
V
DD
Pin Voltage
L
X
Pin Voltage
CE Pin Input Voltage
TEST Pin Input Voltage
V
OUT
/
V
FB
Pin Input Voltage
L
X
Pin Output Current
Power Dissipation (SON-8)*
Operating Temperature Range
Storage Temperature Range
Item
Rating
（AGND=PGND=0V)
Unit
V
V
V
V
V
V
V
mW
°C
°C
−0.3
to 6.5
−0.3
to 6.5
−0.3
to V
IN
+
0.3
−0.3
to V
IN
+
0.3
−0.3
to V
IN
+
0.3
−0.3
to V
IN
+
0.3
±1.5
480
−40
to 85
−55
to 125
∗)
For Power Dissipation, please refer to PACKAGE 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 is not assured.
5
电路观察室
