IXD3235/36/37
Step-
Converter
Synchronous 600 mA Step-Down DC/DC Converter
FEATURES
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Built-in transistors
Operating Input Voltage Range:
2.0 V ~ 6.0 V
(A/B/C types) or 1.8 V ~ 6.0 V (D/E/F/G types)
Output Voltage Range Externally Set:
0.8 V ~ 4.0 V
(internally set) or 0.9 ~ 6.0 V (externally set)
Output Current:
600 mA
High Efficiency:
92%
Oscillation Frequency:
1.2 MHz, 3 MHz
Maximum Duty Cycle:
100%
Operating Modes:
PWM, PWM/PFM auto select or
PWM/PFM manual select
Functions:
Build-in Current Limit, Load Capacitor
Discharge, High Speed Soft start
0
Operating Ambient temperature:
-40 ~ +85 C
Packages:
SOT-25, USP-6C, USP-6EL, WLP-5-03
EU RoHS Compliant, Pb Free
APPLICATION
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Mobile Phones
Bluetooth headsets
Digital home appliances
Office automation equipment
Various portable equipment
DESCRIPTION
The IXD3235/36/37 series is a group of synchronous-
rectification type DC/DC converters with a built-in
0.52
Ω
N-channel synchronous rectification transistor
and 0.42
Ω
P-channel switching transistor providing
up to 600 mA output current.
Operating voltage range is from 2.0 V to 6.0 V (A
½
C types) or 1.8 V to 6.0 V (D
½
G types). For the D/F
types, which have a reference voltage of 0.8 V with ±
2.0% accuracy, the output voltage can be set from
0.9 V by using two external resistors.
The A/B/C/E/G types have a fixed output voltage
from 0.8 V to 4.0 V in increments of 0.05 V with
± 2.0% accuracy. The device requires only an
inductor and two externally connected ceramic
capacitors. The built-in oscillator, either 1.2 MHz or
3.0 MHz, can be selected.
The IXD3235 operates in PWM mode, the IXD3236
automatically switches between PWM/PFM modes,
and the IXD3237 allows switch manually between the
PWM and the automatic PWM/PFM switching control
modes. This allows fast response, low ripple, and
high efficiency over the full range of loads from light
to heavy.
The soft start and current control functions are
internally optimized. All circuits are disabled in a
standby mode to reduce current consumption to less
than 1.0
µA.
The B/F/G types have a 0.25 ms high-speed soft-
start for quick turn-on. The built-in Under Voltage
Lockout (UVLO) function forces the internal
P-channel transistor OFF, when input voltage
becomes 1.4 V or lower.
The B to G types have the output capacitor C
L
discharge circuitry, which allows fast C
L
discharge
when IC goes into standby mode.
Device is available in four types of packages: SOT-
25, USP-6C, USP-6EL, and WLP-5-03.
TYPICAL APPLICATION CIRCUITS
TYPICAL PERFORMANCE CHARACTERISTIC
Efficiency vs. Output Current (f
OSC
= 1.2 MHz, V
OUT
= 1.8 V)
PWM/PFM Automatic Switching mode
IXD3235/36/37 A, B, C, E, and G types
IXD3235/36/37 D and F types
© 2014 IXYS Corp.
Characteristics subject to change without notice
1
Doc. No. IXD3235_DS, Rev. N0
IXD3235/36/37
ABSOLUTE MAXIMUM RATINGS
PARAMETER
V
IN
Pin Voltage
L
X
Pin Voltage
V
OUT
Pin Voltage
FB Pin Voltage
CE/MODE Pin Voltage
Lx Pin Current
SOT-25
Power Dissipation
USP-6C
USP-6EL
WLP-5-03
Operating Temperature Range
Storage Temperature Range
T
OPR
T
STG
P
D
SYMBOL
V
IN
V
LX
V
OUT
V
FB
V
CE
I
LX
RATINGS
– 0.3 ~ 6.5
– 0.3 ~ V
IN
+ 0.3
– 0.3 ~ 6.5
– 0.3 ~ 6.5
– 0.3 ~ 6.5
±1500
250
120
120
750
– 40 ~ + 85
– 50 ~ +125
0
0
1
UNITS
V
V
V
V
V
mA
mW
C
C
ELECTRICAL OPERATING CHARACTERISTICS
IXD3235/36/37 A series, V
OUT
= 1.8 V, Ta = 25
0
C
PARAMETER
Operating Voltage Range
Output Voltage
Maximum Output Current
UVLO Voltage
Supply
Current
IXD323xA18Cxx
IXD323xA18Dxx
IXD323xA18Cxx
IXD323xA18Dxx
SYMBOL
V
IN
V
OUT
I
OUT_MAX
V
UVLO
I
Q
I
STB
f
OSC
I
PFM12)
t
PON_MAX12)
D
MAX
D
MIN
EFFI
R
LXH1
R
LXH2
R
LXL1
R
LXL2
I
LXH
I
LXH
I
LIM
∆
∆
V
CEH
V
CEL
6), 13)
CONDITIONS
V
IN
= V
CE
= 5.0 V, I
OUT
= 30 mA
V
IN
= V
OUT(E)
+ 2.0 V, V
CE
= 1.0 V
9)
V
CE
= V
IN
, V
OUT
= 0
1), 11)
MIN.
2.0
600
1.00
TYP.
-
MAX.
6.0
UNIT
V
V
mA
V
µA
µA
kHz
mA
CIRCUIT
1.764 1.800 1.836
1.40
15
21
0
1020
2550
120
170
100
0
92
86
0.35
0.42
0.45
0.52
0.01
0.01
900
1050
±100
0.65
0
V
IN
–
0.25
-0.1
6.0
0.25
V
IN
-1.0
0.55
0.67
0.65
0.77
1.0
1.0
1350
1220
3000
160
220
1.78
33
35
1.0
1380
3460
200
270
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= 5.0 V, V
CE
= 0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= V
OUT(E)
+ 2 V, V
CE
= 1.0 V, I
OUT
= 100 mA
V
IN
= V
CE
= V
OUT(E)
+ 2 V, , I
OUT
= 1 mA (see table A)
V
IN
= V
CE
= (see table B), I
OUT
= 1 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 0.9 V
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= V
CE
= V
OUT(E)
+ 1.2 V, I
OUT
= 100 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, I
LX
= 100 mA
V
IN
= V
CE
= 3.6 V, V
OUT
= 0 V, I
LX
= 100 mA
V
IN
= V
CE
= 5.0 V
V
IN
= V
CE
= 3.6 V
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, V
LX
= 5.0 V
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, V
LX
= 5.0 V
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 0.9 V
8)
-40
0
C
≤
T
OPR
≤
85
0
C, I
OUT
= 30 mA
V
OUT
= 0 V
V
OUT
= 0 V
I
OUT
= 1 mA
I
OUT
= 1 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V
Standby Current
Oscillation
Frequency
PFM
IXD323xA18Cxx
Switching
IXD323xA18Dxx
Current
P-channel ON time maximum
Maximum Duty Cycle Ratio
Minimum Duty Cycle Ratio
Efficiency
2)
IXD323xA18Cxx
IXD323xA18Dxx
3)
2D
max
3D
MAX
%
%
%
Ω
Ω
Ω
Ω
µA
µA
mA
ppm/
0
C
V
V
L
X
“H” ON Resistance 1
3)
L
X
“H” ON Resistance 2
L
X
“L” ON Resistance 1
L
X
“L” ON Resistance 2
L
X
“L” Leakage Current
4)
4)
L
X
“H” Leakage Current
5)
5)
Current Limit
10)
Output Voltage Temperature
Characteristics
CE “H” Voltage
14)
CE “L” Voltage
15)
PWM mode Start Voltage
PWM/PFM mode
Start Voltage
6), 13)
CE “H” Current
V
PWM
V
PFM
I
ENH
0.1
µA
© 2014 IXYS Corp.
Characteristics subject to change without notice
2
Doc. No. IXD3235_DS, Rev. N0
IXD3235/36/37
CE “L” Current
Soft-Start
Time
Latch Time
7)
Short Protection Threshold
Voltage
IXD323xA18Cxx
IXD323xA18Dxx
I
ENL
t
SS
t
LAT
V
SHORT
V
IN
= 5.0 V, V
CE
= 0 V, V
OUT
= 0 V
I
OUT
= 1 mA (see table C)
V
IN
= V
CE
= 5.0 V, V
OUT
= 0.8 x V
OUT(E),
L
X
short with
1
Ω
resistor to ground
V
IN
= V
CE
= 5.0 V, L
X
short with 1
Ω
resistor to
ground
-0.1
0.5
0.5
1.0
1.0
0.9
0.1
2.5
2.5
20.0
µA
ms
ms
V
0.675 0.900 1.150
NOTE:
Test conditions: Unless otherwise stated, V
IN
= 5.0 V, V
OUT(E)
= Nominal Voltage
1) Including hysteresis operating voltage range
2) EFFI = {(output voltage × output current) / (input voltage × input current)} × 100%
3) ON resistance (Ω) = (V
IN
- Lx pin measurement voltage) / 100mA
4) Design target value
5) A 10µA (maximum) current may leak at high temperature
6) The CE/MODE pin of the IXD3237A series functions also as an external switching pin between PWM and PWM/PFM control. Control
is switched to the automatic PWM/PFM switching mode when the CE/MODE pin voltage is equal to or greater than V
IN
minus 0.3 V,
and to the PWM mode when the CE/MODE pin voltage is equal to or lower than VIN minus 1.0V. However, it should be equal to or
greater than V
CEH
7) Time from moment when V
OUT
is shorted to GND via 1
Ω
resistor to the moment, when Current Limit generates pulse stopping L
X
oscillations
8) When V
IN
is less than 2.4 V, current limit may not be reached because of voltage drop across ON resistance
9) When the difference between input and output voltage is small, some cycles may be skipped completely before current maximizes. If
load current increases in this state, output voltage will decrease because of the voltage drop across P-channel transistor
10) Current limit denotes the level of an inductor peak current
11) Voltage, when L
X
pin voltage is “L”=+0.1 V ~ -0.1 V
12) Not for IXD3235 series, because they have PWM mode only
13) The IXD3237 series only
14) Voltage at which L
X
pin state changes from “L” to “H” = V
IN
~ V
IN
- 1.2 V”
15) Voltage at which L
X
pin state changes from “H” to “L” ”=+0.1 V ~ -0.1 V
© 2014 IXYS Corp.
Characteristics subject to change without notice
3
Doc. No. IXD3235_DS, Rev. N0
IXD3235/36/37
ELECTRICAL OPERATING CHARACTERISTICS (CONTINUED)
IXD3235/36/37 B/C/E/G series, V
OUT
= 1.8 V, Ta = 25
0
C
PARAMETER
Operating Voltage
Range
Output Voltage
Maximum Output Current
UVLO Voltage
Supply
Current
IXD323xx18Cxx
IXD323xx18Dxx
IXD323xx18Cxx
IXD323xx18Dxx
B/C series
E/G series
SYMBOL
V
IN
V
OUT
I
OUT_MAX
V
UVLO
I
Q
I
STB
f
OSC
I
PFM12)
t
PON_MAX12)
D
MAX
D
MIN
EFFI
R
LXH1
R
LXH2
R
LXL1
R
LXL2
I
LXH
I
LXH
I
LIM
∆
∆
V
CEH
V
CEL
6), 13)
CONDITIONS
MIN.
2.0
1.8
TYP.
-
MAX.
6.0
6.0
UNIT
V
V
mA
V
µA
µA
kHz
mA
CIRCUIT
V
IN
= V
CE
= 5.0 V, I
OUT
= 30 mA
V
IN
= V
OUT(E)
+ 2.0 V, V
CE
= 1.0 V
V
CE
= V
IN
, V
OUT
= V
OUT(E)
x 0.5 V
9)
1), 11), 16)
1.764 1.800 1.836
600
1.00
1.40
15
21
0
1020
2550
120
170
100
0
92
86
0.35
0.42
0.45
0.52
0.01
0.01
900
1050
±100
0.65
0
V
IN
–
0.25
-0.1
-0.1
0.25
0.5
0.5
1.0
0.32
0.9
6.0
0.25
V
IN
-1.0
0.55
0.67
0.65
0.77
1.0
1.0
1350
1220
3000
160
220
1.78
33
35
1.0
1380
3460
200
270
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= 5.0 V, V
CE
= 0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= V
OUT(E)
+ 2 V, V
CE
= 1.0 V, I
OUT
= 100 mA
V
IN
= V
CE
= V
OUT(E)
+ 2 V, , I
OUT
= 1 mA (see table A)
V
IN
= V
CE
= (see table B), I
OUT
= 1 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 0.9 V
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 1.1 V
V
IN
= V
CE
= V
OUT(E)
+ 1.2 V, I
OUT
= 100 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, I
LX
= 100 mA
V
IN
= V
CE
= 3.6 V, V
OUT
= 0 V, I
LX
= 100 mA
V
IN
= V
CE
= 5.0 V
V
IN
= V
CE
= 3.6 V
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, V
LX
= 5.0 V
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V, V
LX
= 5.0 V
V
IN
= V
CE
= 5.0 V, V
OUT
= V
OUT(E)
x 0.9 V
8)
-40
0
C
≤
T
OPR
≤
85
0
C, I
OUT
= 30 mA
V
OUT
= 0 V
V
OUT
= 0 V
I
OUT
= 1 mA
I
OUT
= 1 mA
V
IN
= V
CE
= 5.0 V, V
OUT
= 0 V
V
IN
= 5.0 V, V
CE
= 0 V, V
OUT
= 0 V
Standby Current
Oscillation
Frequency
PFM
IXD323xx18Cxx
Switching
IXD323xx18Dxx
Current
P-channel ON time maximum
Maximum Duty Cycle Ratio
Minimum Duty Cycle Ratio
Efficiency
2)
IXD323xx18Cxx
IXD323xx18Dxx
2D
max
3D
MAX
%
%
%
Ω
Ω
Ω
Ω
µA
µA
mA
ppm/
0
C
V
V
L
X
“H” ON Resistance 1
3)
L
X
“H” ON Resistance 2
3)
L
X
“L” ON Resistance 1
L
X
“L” ON Resistance 2
L
X
“L” Leakage Current
4)
4)
5)
L
X
“H” Leakage Current
5)
Current Limit
10)
Output Voltage Temperature
Characteristics
CE “H” Voltage
14)
CE “L” Voltage
15)
PWM mode Start Voltage
PWM/PFM mode
Start Voltage
6), 13)
CE “H” Current
CE “L” Current
IXD323xB(G)18Cxx
Soft-Start IXD323xC(E)18Cxx
Time
IXD323xB(G)18Dxx
IXD323xC(E)18Dxx
Latch Time
7)
B/C series
Short Protection
Threshold Voltage E/G series
C
L
Discharge Resistance
V
PWM
V
PFM
I
ENH
I
ENL
0.1
0.1
0.4
2.5
0.50
2.5
20.0
µA
µA
t
SS
I
OUT
= 1 mA (see table C)
ms
t
LAT
V
SHORT
R
DCL
V
IN
= V
CE
= 5.0 V, V
OUT
= 0.8 x V
OUT(E),
L
X
short with
1
Ω
resistor to ground
V
IN
= V
CE
= 5.0 V, L
X
short with 1
Ω
resistor to
ground
V
IN
= V
LX
= 5.0 V, V
CE
= 0 V, V
OUT
- open
1.0
ms
V
Ω
0.675 0.900 1.150
0.338 0.450 0.563
200
300
450
NOTE:
Test conditions: Unless otherwise stated, V
IN
= 5.0 V, V
OUT(E)
= Nominal Voltage
1) Including hysteresis operating voltage range
2) EFFI = {(output voltage × output current) / (input voltage × input current)} × 100%
3) ON resistance (Ω) = (V
IN
- Lx pin measurement voltage) / 100mA
4) Design target value
© 2014 IXYS Corp.
Characteristics subject to change without notice
4
Doc. No. IXD3235_DS, Rev. N0
IXD3235/36/37
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
A 10µA (maximum) current may leak at high temperature
The CE/MODE pin of the IXD3237A series functions also as an external switching pin between PWM and PWM/PFM control. Control
is switched to the automatic PWM/PFM switching mode when the CE/MODE pin voltage is equal to or greater than V
IN
minus 0.3 V,
and to the PWM mode when the CE/MODE pin voltage is equal to or lower than VIN minus 1.0V. However, it should be equal to or
greater than V
CEH
Time from moment when V
OUT
is shorted to GND via 1
Ω
resistor to the moment, when Current Limit generates pulse stopping L
X
oscillations
When V
IN
is less than 2.4 V, current limit may not be reached because of voltage drop across ON resistance
When the difference between input and output voltage is small, some cycles may be skipped completely before current maximizes. If
load current increases in this state, output voltage will decrease because of the voltage drop across P-channel transistor
Current limit denotes the level of an inductor peak current
Voltage, when L
X
pin voltage is “L”=+0.1 V ~ -0.1 V
Not for IXD3235 series, because they have PWM mode only
The IXD3237 series only
Voltage at which L
X
pin state changes from “L” to “H” = V
IN
~ V
IN
- 1.2 V”
Voltage at which L
X
pin state changes from “H” to “L” ”=+0.1 V ~ -0.1 V
Voltage at which V
OUT
becomes more than V
IN
, while V
IN
is rising from 0 V to V
OUT (E)
x 0.5 V
© 2014 IXYS Corp.
Characteristics subject to change without notice
5
Doc. No. IXD3235_DS, Rev. N0
