Preliminary Specification
TM
CR-F33T
PFM STEP-UP
DC/DC CONVERTER
GENERAL DESCRIPTION
The
CR-F33T
is a PFM step-up DC/DC
converter IC and has a high efficiency.
These devices consist of a bandgap, a
comparator, an oscillator, a driver, and a
high current output switch.
The CR-F33T provides a higher fixed
voltage from the smaller input voltage.
The CR-F33T is used for single- or
dual-cell battery operation.
FEATURES
BLOCK DIAGRAM
VDD
Bandgap
LX
Digital
Control
FB
Clock
Select
VSSA
EN
150KHz
OSC
VSS
PIN CONFIGURATION
Low Voltage Operation Possible
Low Supply Current
Small Number of External
Components
Internal Power Switch
APPLICATIONS
Battery-Powered Instruments
Hand-Held Instruments
Hand-Held Communication
Instruments
Cameras
SOP-8
(Top View)
VDD 1
FB 2
EN 3
NC 4
8 LX
7 VSSA
6 VSS
5 NC
SOT-89-3
(Top View)
1
3
2
VSS VDD LX
ORDERING INFORMATION
CR-FXXX
Step-up
Package
P: SOP-8
T: SOT-89-3
Output Voltage
33 : 3.3V
1
Preliminary Specification
TM
CR-F33T
PFM STEP-UP
DC/DC CONVERTER
PIN DESCRIPTION
Pin No.
1
2
3
4
5
6
7
8
Pin Name
VDD
FB
EN
NC
NC
VSS
VSSA
LX
Pin Function
Output voltage pin and also power supply pin for
the device
The pin of feedback voltage
Chip enable pin
No internal connection to this pin
No internal connection to this pin
Ground pin
Ground pin
Switch pin, connected to inductor/diode
STEP-UP CONVERTER APPLICATION
1N5819
220uH
1N5819
220uH
VDD
EN
VDD
FB
100uF
CR-F33-P
VSSA
V
IN
100uF
LX
CR-F33-T
LX
V
IN
Absolute Maximum Ratings
Supply Voltage-------------------------------------------------------------- - 0.3V to 7V
Input Voltage---------------------------------------------------------------- - 0.3V to V
DD
+0.3
Operating Temperature Range--------------------------------------------- 0
o
C to 50
o
C
Storage Temperature Range----------------------------------------------- - 40
o
C to 150
o
C
VSS
VSS
2
Preliminary Specification
TM
CR-F33T
PFM STEP-UP
DC/DC CONVERTER
Electrical Characteristics
Parameter
Start-Up Voltage
Holding Voltage
Input Voltage
Output Voltage
No-Load Input Current
Standby Current
Input Low Voltage
Input High Voltage
Oscillator Frequency
Efficiency
Symbol
V
ST
V
Hold
V
IN
V
DD
I
IN
I
SB
V
IL
V
IH
Fosc
η
Test Conditions
I
load
= 1mA
I
load
= 1mA
No Load
Min.
0.45
1
3
Typ. Max. Units
0.9
1
V
V
3.5
3.3
8
3.6
14
2
V
V
μA
μA
V
V
KHz
%
No Load
V
EN
= 0
Enable/Disable Pin
Enable/Disable Pin
0
1
0.4
V
DD
150
V
IN
= 1.5V, I
load
= 10mA
83
OPERATION OF STEP-UP CONVERTER
A step-up converter diagram is illustrated below. In the diagram, the converter can
generate a fixed, higher voltage from a lower one. When SW stays ON, I
L1
flows
through L, and the converter converts the electric energy into the magnetic one and
stores it in L, in which I
max
is proportional to t
on
; when SW lies OFF, Shottky diode is
forced to be ON, while the energy stored in inductor L be discharged into capacitor,
thereby charging the output voltage to a value expected.
I
L
I
L2
L
+
I
L1
V
IN
--
SW
C
L
V
out
--
I
Lmin
t
on
T=1/f
osc
t
off
t
D
I
out
+
I
Lmax
3
Preliminary Specification
TM
CR-F33T
PFM STEP-UP
DC/DC CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
L=47uH; C=100uF
90
Vin=3V
80
70
Vin=1.2V
60
Efficiency (% )
50
40
30
20
10
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
Vin=1.5V
Vin=2V
4
Vin=3V
Vin=2.5V
3
Vin=1.2V
E fficiency (% )
Vin=1.5V
Vin=2.5V
Vin=2V
2
1
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
L=100uH; C=100uF
90
80
70
60
Efficiency (%)
50
40
30
20
10
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
Vin=1.5v
4
Vin=3V
Vin=1.2V
Vin=2V
Vin=2.5V
Vin=3V
3
Vin=1.5V
Vin=1.2V
Efficiency (%)
Vin=2.5V
Vin=2V
2
1
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
4
Preliminary Specification
TM
CR-F33T
PFM STEP-UP
DC/DC CONVERTER
L=150uH; C=100uF
100
90
Vin=3V
4
80
70
Efficiency (%)
60
Vin=1.5V
50
40
30
1
Vin=1.2V
3
Vin=3V
Efficiency (%)
Vin=1.2V
Vin=1.5V
Vin=2V
Vin=2.5V
Vin=2V
Vin=2.5V
2
20
10
0
0
10
20
30
40
50
Iload(mA)
60
70
80
90
100
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
L=220uH; C=100uF
90
80
4
Vin=3V
70
60
E fficiency (% )
Vin=1.5V
50
40
30
20
10
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
Vin=2V
Vin=3V
Vin=1.2V
3
Vin=1.5V
Vin=2.5V
Vin=2V
Vin=1.2V
E fficiency (% )
Vin=2.5V
2
1
0
0
10
20
30
40
50
Iload (mA)
60
70
80
90
100
5
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