R1232D Series
PWM Step-down DC/DC Converter with Synchronous Rectifier
EK-129-121001 Step-down DC/DC Converter
The R1232D Series are low supply current CMOS-based PWM step-down DC/DC converters with synchronous rectifier. R1232D
includes a soft start circuit, under-voltage lockout circuit (UVLO) and latch type protection circuit. By simply using an inductor, a
capacitor, and (resistors) as external components, a high-efficiency step-down DC/DC converter can be easily configured. R1232D
comes in two types: R1232Dxx1A/B with internally fixed output voltage and R1232D001C/D with adjustable output voltage with
external resistors.
FEATURES
• Supply Current (IDD)························
Typ. 140
μ
A (1MH z), 240
μ
A (2.25MHz) (No switching)
• Standby Current (Istandby)··················Max. 5μA (CE="L")
• Input Voltage Range (VIN)···············2.6V to 5.5V
• Output Voltage Range (VOUT)··········0.9V to 3.3V (Internally fixed, R1232Dxx1A/B)
Externally adjustable (Feedback voltage : 0.8V, R1232D001C/D)
• Output Voltage Accuracy················± 2% (Feedback Voltage Accuracy : ± 16mV)
• Oscillator Frequency (fosc)···············1MHz, 2.25MHz
•
Oscillator Maxim um Duty Cycle (Maxduty)
·····Min. 100%
• UVLO Detect Voltage (VUVLO) ·········Typ. 2.25V
• Soft Start Time (tstart)·······················Typ. 1ms (1MHz)
Typ. 0.4ms (2.25MHz)
• Coil-current Limit Circuit
················Current limit Typ. 1.4A
• Latch Type Protection Circuit··········
Delay time for protection
Typ. 2ms
• Package··········································SON-8
• Ceramic capacitors can be used.···
C
IN
=C
OUT
=10
μ
F or more
BLOCK DIAGRAMS
R1232Dxx1A/B R1232D001C/D
(Internally fixed output voltage type) (Externally adjustable output voltage type)
2
VIN
LX
PGND
VOUT
CE
Output
Contorol
3
Current Li mit
1
QR
S
Oscillator
TEST Circuit
TEST “L” or GND Fixed
6
Slope
Compensation
Phase
Compensation
5
Soft Start
UVLO
4
“H” Active
VDD 7
A
GND
Error
Amplifer
PWM
Comparator
8 Vref
Chip Enable
2
VIN
LX
PGND
VFB
CE
Output
Contorol
3
Current Limi t
1
QR
S
Oscillator
TEST Circuit
TEST “L” or GND Fixed
6
Slope
Compensation
Phase
Compensation
5
Soft Start
UVLO
Chip Enable
4
“H” Active
VDD 7
A
GND
Error
Amplifer
PWM
Comparator
8Vref
SELECTION GUIDE TYPICAL APPLICATIONS
Halogen Free
Package
Q'ty per Reel
Part No.
R1232D
.
xx
.
1
.
∗
-TR-F
- SON-8 3,000 pcs
R1232D
.
00
.
1
.
$
.
-TR-F
.
xx
.
:
Specify the output voltage within the range of
0.9V (
.
09
.
) to 3.3V (
.
33
.
)
in 0.1V steps.
For the externally adjustable output voltage type
(
.
00
.
)
.
∗
.
:
Select the oscillator frequency and output voltage type from
(
.
A
.
)
1MHz, internally fixed type or
(
.
B
.
)
2.25MHz, internally fixed type.
.
$
.
:
Select the oscillator frequency and output voltage type from
(
.
C
.
) 1MHz
,
externally adjustable type or
(
.
D
.
) 2.25MHz
,
externally adjustable type.
R1232Dxx1A/B
PGND
VIN
VDD
CE VOUT
TEST
AGND
LX
1L VOUT
CIN
COUT
LOAD
2
3
4
8
7
6
5
L=4.7μH, 2.2μH
CIN=10μF, COUT=10μF
R1232D001C/D
PGND
VIN
VDD
CE VFB
TEST
AGND
LX L VOUT
CIN
COUT
Cb R1
R2
1
2
3
4
8
7
6
5
LOAD
For VOUT=2.0V,
R1=33kΩ, R2=22kΩ, Cb=100pF
PACKAGE TYPICAL CHARACTERISTIC
SON-8
1
8
2
7
3
6
4
5
4
5
3
6
2
7
1
8
Bottom View Top View
∗
1 PGND
2 VIN
3 VDD
4 CE
5VOUT or VFB
6TEST
7 AGND
8Lx
R1232D331 A Efficiency vs. Output Current
∗) The tab suspension leads are substrate level (GND).
APPLICATIONS
• Power source for hand-held communication equipment, cameras, and VCRs
• Power source for home appliances • Power source for battery-powered equipment
0
20
100
80
50
30
90
70
60
10
40
1 10 100 1000
Output Current IOUT (mA)
VIN=5.0V
Efficiency η
(%)
RICOHCOMPANY,LTD.
ElectronicDevicesCompany
http://www.ricoh.com/LSI/
For the conservation of the global environment, Ricoh is advancing the decrease of the negative environmental impact material.
After Apr. 1, 2006, we will ship out the lead free products only. Thus, all products that will be shipped from now on comply with RoHS Directive.
Basically after Apr. 1, 2012, we will ship out the Power Management ICs of the Halogen Free products only. (Ricoh Halogen Free products are
also Antimony Free.)
Halogen Free
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