OM1575 Series
OMH1575 Series
STEP-DOWN SWITCHING VOLTAGE REGULATOR IN
HERMETIC ISOLATED PACKAGE
1.0 Amp, 5V, 12V, 15V And Adjustable Output
Voltage Versions In MO-078 Metal Package
FEATURES
•
•
•
•
•
•
•
Similar To Industry Standard LM1575
Available in 5V, 12V, 15V, And Adjustable Versions
1.0 Amp Output
Wide Input Voltage Range, 4V to 60V
53 kHz Fixed Frequency Internal Oscillator
High Efficiency
Hermetic Metal Packages
DESCRIPTION
This series of regulators are monolithic integrated circuits designed for the active
functions of a step down, buck or buck/boost regulator. It requires only four readily
available standard components to complete the DC to DC converter design at 1 Amp.
Current limiting and thermal shutdown features fully protect the device against
overstress. The hermetic package is ideally suited for those critical environments
requiring high reliability over a wide operating temperature range.
ABSOLUTE MAXIMUM RATINGS
@ T
C
= 25°C
Maximum Supply Voltage
OM1575. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 V
OMH1575 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 V
ON/OFF Pin Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V V V
IN
Output Voltage To Ground (Steady State) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1 V
Power Dissipation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally Limited
Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55°C to + 150°C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65°C to + 150°C
Thermal Resistance, Rq
JC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4°C/W
Lead Soldering Temperature (10 seconds). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
3.3
BLOCK DIAGRAM
INPUT
Feedback
Internal
Resistors
For Fixed
Options Only
+
E/A
-
REF
REG
ON/OFF
ON/OFF
+
PWM
-
OSC
RESET
DRV
PROTECTION
Output
GND
4 11 R0
3.3 - 33
OM1575 OMH1575 Series
Unless otherwise specified V
IN
= 12V for 5V and ADJ options; 25V for 12V; and
,
30V for 15V models; V
OUT
= 5V for ADJ, I
O
= 0.2A to 1A, T
J
= 25°C. V
IN
rated = 40V and 60V for OMH Series.
Test Conditions
Parameter
OM1575-05
Symbol
V
IN
V
O
8V to V
IN
Rated
OM1575-12
V
O
15V to V
IN
Rated
OM1575-15
V
O
18V to V
IN
Rated
Feedback Voltage
V
OUT
= 5V
OM1575-A
Feedback Bias Current
I
B
12V
0.2A
Over Temp.
Efficiency/Option
5
12
15
A V
O
= 5V
Switching Frequency
Saturation Voltage(1)
Maximum Duty Cycle (On)(3)
Current Limit (1)
Peak Current
Output Leakage Current (2)
Output = 0V
Output = -1V
Quiescent Current (2)
I
O
Over Temp.
I
L
V
IN
Rated
7.5
5
2
30
10
12
50
Over Temp.
V
IH
2.2
Over Temp.
V
IL
Over Temp.
On/Off Input Current
On/Off = 5V (Off)
On/Off = 5V (Off)
I
IH
I
IL
0.2A
12
0
30
10
µA
1.2
2.4
1.4
1.0
0.8
V
V
200
500
µA
mA
mA
F
SX
Over Temp.
V
SAT
1A
Over Temp.
93
Peak Current
I
CL
T
on
3µsec
Over Temp.
1.7
1.3
15V
18V
12V
47
43
0.9
98
2.2
3.0
3.2
A
n
1A
82
88
90
82
52
58
62
1.2
1.4
V
%
kHz
%
V
FB
8V to V
IN
Rated
0.2A
Over Temp.
0.2A
Over Temp.
0.2A
Over Temp.
I
O
0.2A
Over Temp.
T
J
MIN.
4.95
4.80
4.85
11.88
11.52
11.64
14.85
14.40
14.55
1.217
1.193
1.205
50
TYP.
MAX.
5.05
5.20
5.15
12.12
12.48
12.36
15.15
15.60
15.45
1.243
1.267
1.255
100
500
nA
V
V
V
V
UNIT
Limits
ELECTRICAL CHARACTERISTICS
DC
3.3
Standby Quiescent
Current (On/Off Pin = 5V)
On/Off Pin Logic
Input Level
V
OUT
= 0V
V
OUT
= Option
I
STBY
Notes:
Over Temperature: -55°C to 150°C.
(1) Output sourcing current - resistive load, no inductor or capacitor.
(2) Feedback = V
O
+1.0V.
(3) Feedback = 0V.
(4) Not all parameters are 100% tested during production. Consult the factory for more information.
3.3 - 34
OM1575 OMH1575 Series
OPERATIONAL DATA
Dropout Voltage
∆V
OUT
= 5%
R
IND
= 0.2Ω
Minimum Operating
Voltage
5.0
Input Voltage (V)
4.0
3.0
2.0
1.0
I
O
= 200mA
V
OUT
= 1.23V
2.5
V
IN
- V
OUT
(V)
2.0
1.5
1.0
0.5
I
O
= 1A
I
O
= 200mA
0
25
50
75 100 125 150
0
-75 -50 -25
0
-75 -50 -25
0
25
50
75 100 125 150
Junction Temperature (°C)
Junction Temperature (°C)
Normalized Feedback Voltage (mV)
20
15
10
5
0
-5
-10
0
Line Regulation
(Adjustable Version Only)
Feedback Current (nA)
Normalized to V
IN
= 10V
I
O
= 200mA, V
OUT
= 5V
T
J
= 25°C
Feedback Pin Current
75
50
25
0
-25
-50
-75
-75 -50 -25
0
25
50
75 100 125 150
10
20
30
40
60
Input Voltage (V)
Junction Temperature (°C)
3.3
25
Normalized Feedback
Voltage (mV)
15
5
0
-5
-15
-25
-75 -50 -25
0
25
50
75 100 125 150
Normalized Feedback Voltage
(Adjustable Version Only)
V
IN
= 12V
I
O
= 200mA
Normalized to T
J
= 25°C
15
10
Feedback Voltage
Change (mV)
5
0
Feedback Voltage vs Duty Cycle
(Adjustable Version Only)
I
O
= 200mA
V
IN
= 40V
V
IN
= 7V
-5
-10
-15
0
20
40
60
80
100
Junction Temperature (°C)
Duty Cycle (%)
3.3 - 35
OM1575 OMH1575 Series
OPERATIONAL DATA
Supply Current vs. Duty Cycle
20
V
IN
= 7V
15
V
IN
= 40V
10
I
O
= 200mA
20
18
Supply Current (mA)
16
14
12
10
8
80
100
6
0
I
LOAD
= 200mA
10
20
30
Input Voltage (V)
40
60
I
LOAD
= 1A
Measured At Ground Pin
T
J
= 25°C, V
OUT
= 5V
Supply Current
Supply Current (mA)
5
20
40
60
Duty Cycle (%)
Current Limit
3.0
Saturation Voltage (V)
1.2
1.0
0.8
Switch Saturation Voltage
Output Current (A)
2.0
V
IN
= 25V
T
J
= -55°C
T
J
= 25°C
0.6
T
J
= 150°C
0.4
0.2
0.2
0.4
0.6
0.8
1.0
1.0
0
-75 -50 -25
0
25
50
75 100 125 150
Junction Temperature (°C)
Switch Current (A)
3.3
95
90
Efficiency (%)
85
V
OUT
= 12V
Efficiency
Standby Quiescent Current (µA)
200
Standby Quiescent Current
V
IN
= 40V
150
V
ON/OFF
= 5V
100
V
IN
= 12V
50
-75 -50 -25 0 25 50 75 100 125 150
Junction Temperature (°C)
1A
200mA
80
75
70
65
0
1A
10
20
30
40
60
200mA
V
OUT
= 3V
Input Voltage (V)
3.3 - 36
OM1575 OMH1575 Series
Catch Diode
If the output must be capable of a sustained short, the I
F
rating must be above 3A. The use of an ultra fast diode
with soft recovery characteristics or a Schottky will be adequate. The major impact on Schottky versus an ultra
fast is efficiency. Schottkys will provide approximately 4% to 5% improvement for output voltage below 12V,
whereas above 12V the difference will become less significant. Breakdown rating must be in excess of V
IN
for
margin.
Input Capacitor
The value shown will be adequate for most applications. Ripple voltage at the switching frequency is caused by
the input capacitor supplying load current during the on time of the power switch. The use of a low ESR
switching type capacitor will minimize ripple to an acceptable level.
Layout
Use short connections with a central point ground to prevent improper operation caused by stray inductance and
ground loops.
Output Capacitor
Ripple voltage on V
OUT
is directly related to the value of C
OUT
and the internal resistance ESR of C
OUT
. Output
noise can be lowered by increasing C
OUT
or by selecting a capacitor with a lower ESR. ESR must be
approximately 0.07 or above to maintain stability, otherwise raise value of C
OUT
.
BUCK MODE FIXED VOLTAGE
1
+
C
IN
68µF
ON/
OFF
REC
+
E/A
-
REF
5
3
+
PWM
-
OSC
RESET
330µH
L1
2
D1
3A
+
C
OUT
330µF
4
DRV
PROTECTION
BUCK MODE ADJUSTABLE VOLTAGE
1
+
C
IN
68µF
ON/
OFF
REC
+
E/A
-
REF
5
3
+
PWM
-
OSC
RESET
330µH
L1
2
D1
3A
+
330µF
C
OUT
2K
R2
R1
3.3
4
DRV
PROTECTION
The above fixed and adjustable voltage selections will be adequate for most applications for output currents from
150mA to 1.0A. Applications of V
OUT
below 5V or above 24V may require component adjustment for maximum
performance; please contact factory for application assistance.
3.3 - 37
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