4. DC/DC Converters __________________________________________________________________________________
XC6385 SeriesꢀPFM (Frequency) Controlled, Step-up DC/DC Converter IC
DETAILS
General Description
Features
The XC6385 series is a group of PFM (frequency) controlled
step-up DC/DC converters. The XC6385 series employs
CMOS process and laser trimming technologies to attain low
power and high accuracy.
Low noise
Operating voltage range: 0.9V - 10V
Output voltage range: 2.0V - 7.0V
(programmable in 0.1V steps)
A common problem among pagers is one of noise, but with
the XC6385, high frequency noise that occurs during switch-
ing is reduced.
Output Voltage Accuracy: ± 2.5%
Maximum oscillator frequency: 100kHz ( ± 15% )
Built-in switching transistor
Output voltage is programmable in 0.1V steps between 2.0V -
7.0V and maximum frequency is 100 kHz (typ.)
With a built-in switching transistor, a step-up circuit can be
configured using a coil, diode and capacitor connected exter-
nally.
CE function and/or separated VDD/VOUT types selectable with 5 pin
packages
Small package: SOT-23/25 mini-mold (3 pin, 5 pin)
SOT-89/89-5 mini-power mold (3 pin, 5 pin)
Also available is a CE (chip enable) function that reduces
power consumption during shut-down mode, and an inde-
pendent VDD pin function ( separated power supply and volt-
age detect pins ) for fly-back circuits.
SOT-89-5 and SOT-23/25 small packages.
Pin Configuration
Pin Assignment
5
4
(1) XC6385A
3
5
4
PIN NUMBER
PIN
FUNCTION
SOT-89
SOT-89-5
(TOP VIEW)
NAME
SOT-23
(TOP VIEW)
SOT-25
(TOP VIEW)
SOT-23
SOT-89
1
(TOP VIEW)
1
3
2
VSS
VOUT
LX
Ground
Output voltage monitor/
IC internal power supply
Switch
2
3
1
2
1
2
3
1
2
3
1
2
3
Pin Assignment
(2) XC6385C
PIN NUMBER
(3) XC6385E
SOT-25
PIN NUMBER
PIN
PIN
FUNCTION
Ground
FUNCTION
NAME
NAME
SOT-25
4
SOT-89-5
5
SOT-89-5
VSS
4
2
5
1
3
5
2
4
3
1
VSS
VDD
LX
VOUT
NC
Ground
IC internal power supply
Switch
Output voltage monitor
No connection
Output voltage monitor/
IC internal power supply
Switch
2
2
VOUT
5
1
3
4
3
1
LX
CE
NC
Chip enable
No connection
Block Diagram
(1) XC6385A, XC6385C ( VOUT pin also serves as VDD)
(2) XC6385E
VDD
VDD
VDD
LX
VLX limiter
Vref
・
LX
VOUT
VLX limiter
Vref
・
・
・
・
・
VOUT
Buffer
・
Buffer
+
-
PFM Control OSC
100kHz
VSS
+
PFM Control OSC
100kHz
・
VSS
・
-
Chip Enable
CE
Note : The VDD pin is set up for XC6385E
Note : The CE pin is set up for XC6385C
Selection Guide
START
3-pin
Built-inTransistor
XC6385A
XC6385C
XC6385E
Chip Enable
Built-inTransistor
Separated "VDD" and "VOUT" leads
Built-inTransistor
44