500 mA DC-DC Step Down Converter P78AS-Series
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Non isolated
10 Pin SMD package
Function compatible with 78Mxx linear regulator
Efficiency up to 96 %
Operating temperature range -40...+85 °C
Continuous short circuit protected
Thermal shut down
Adjustable output voltage
Model guide
Type
P78AS3R3
P78AS05
P78AS09
P78AS12
P78AS15
Input voltage
Range
Nominal
[VDC]
[VDC]
[VDC]
Output
Adjust trim
Current
range
[VDC]
[mA]
4.5..28
6..28
11..28
14..28
17..28
12
12
24
24
24
3.3
5.0
9.0
12.0
15.0
1.8…5.5
2.5…8
3…11.5
4.5…13.5
4.5…15.5
Voltage
Capacitive
load max.
[µF]
500
500
500
500
500
1000
1000
1000
1000
1000
Efficiency
@ Vin min.
@ Vin max.
[%]
[%]
90
94
95
95
96
75
81
87
90
92
Specifications
Output
Voltage accuracy
Input voltage regulation
Load regulation
Dynamic load stability
Temperature coefficient
Ripple and noise
(at 20 MHz BW)
Short circuit protection
(hiccup mode)
Thermal shutdown
Output current limit
Input
Short circuit input power
Quiescent current
ON control threshold
OFF control threshold
ON / OFF control current
Shut down quiescent current
± 3 %, max.
± 0.5 %, max.
± 0.75 % @ load 10..100 %
± 75 mV @ load 10..100 %
± 0.02 % / °C
25 mVp-p, max.
Continuous, automatic
recovery
150 °C, typ. internal temp.
1.8 A, typ.
1.8 W, max.
15 mA, typ.
> 1.5 V, max. 6 V
<1V
< 2 µA
30 µA, max.
General
Thermal shutdown
Switching frequency
Reliability calc. MTBF @
25 °C MIL-HDBK-217F
Environmental
Operating ambient
temperature
Operating case temperature
Storage temperature
Derating
Humidity
Cooling
Physical
Dimensions
Weight
Case material
Soldering temperature
160 °C, internal junction
330 kHz, typ.
> 2 Mio. h
-40 °C ... +85 °C
100 °C, max.
-55 °C ... +125 °C
see diagram
Up to 95%,
non-condensing
Free air convection
SMD10
15.24 x 8.5 x 7.25 mm
2.3 g
Plastic UL94-V0
See soldering profile
Page 1 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch
500 mA DC-DC Step Down Converter P78AS-Series
Standard application circuit
5
1
P78AS
+Vin
+Vout
Rtd
10
6
7,9
Open
ONstate
C1
10 µF
470
pF
C3
100 µF
C2
Rtu
GND
GND
1.
2.
3.
Type
P78AS3R3
P78AS05
P78AS09
P78AS12
P78AS15
C2
22 µF, 16 V
10 µF, 25 V
C1,C2: Choose a ceramic type capacitors; C3 is require ,for best performance , use a 100 μF or more capacitance.
C1,C2 are require and should be placed close to the pins of the converter, with shortest possible traces.
Do not connect the converter parallel or a hot swap connection.
Adjustment resistor values
Type
Adj. range
Adj. Vout [V]
1.8
2.5
3.0
3.3
3.6
3.9
4.5
4.9
5.0
5.1
5.5
6.5
7.2
8.0
9.0
10.0
11.0
11.5
12.0
13.0
13.5
14.0
14.5
15.0
15.5
P78AS3R3
1.8…5.5 V
Rtd [kΩ]
Rtu [kΩ]
24.31
98.9
364
∞
∞
129.1
59.1
24.3
15.25
14.05
12.8
8.65
P78AS05
2.5…8 V
Rtd [kΩ] Rtu [kΩ]
25.28
47.5
67.3
95.8
140.9
411
2060
∞
∞
208.5
58.5
15.57
7.8
3.15
P78AS09
3…11.5 V
Rtd [kΩ]
Rtu [kΩ]
3.1
5.79
8.47
11.8
19.14
25.77
27.3
29.22
37.8
70.8
115.3
243.1
∞
∞
18.84
4.47
1.61
P78AS12
4.5…13.5 V
Rtd [kΩ]
Rtu [kΩ]
4.55
8.05
9.16
10.41
15
29.8
43.5
64.8
105
180.6
370
635
∞
∞
40.6
15
P78AS15
4.5…15.5 V
Rtd [kΩ]
Rtu [kΩ]
2.69
5.55
6.17
6.98
10
18.5
26.2
36.7
52.9
76.3
111
134.1
167.7
277.8
385
586
1128
∞
∞
88.2
Note: The above dates only are as reference, you could make corresponding adjustment with actual output when they are at practical application.
Application circuit to reduce output ripple.
It is recommented to add a LC filter to output.
5
1
10
C1
10 µF
GND
L 10…47µH
P78AS
+Vin
7,9
+Vout
6
470
pF
C2
100µF
C3
22 µF
GND
Page 2 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch
500 mA DC-DC Step Down Converter P78AS-Series
ON / OFF control function
The ON/OFF pin 10 provides several features for adjusting and sequencing the power supply.
An user has the flexibility of using the ON/OFF pin 10 as:
1) A digital on/off control by pulling down the ON/OFF pin with an open-drain transistor.
1
+Vin
ON/
OFF
C1
7, 9
10
5
P78AS
On/Off
Contr.
+Vout
C2
6
C3
470
pF
GND
GND
2) Line UVLO. If desired to achieve a UVLO voltage, an resistor divider from Vin to ON/OFF to GND can be used to disable the
converter until a higher input voltage is achieved. For example, it is not useful for a converter with 12 V output to start up with a 12 V
input voltage, as theoutput cannot teach regulation. To enable the converter when the input voltage reaches 14 V, a 51 kΩ / 5.1 kΩ
resistor divider from Vin to GND can be connected to the ON/OFF pin. Both the precision 1.25 V threshold and 150 mV hysteresis
are multiplied by the resistor ratio, providing a proportional 12 % hysteresis for any startup threshold. So, the turn off threshold
would be between 12.3 V to 15.7 V.
1
5
P78AS
+Vin
+Vout
51kΩ
10
C1
5.1kΩ
100 µF
6
7,9
470
pF
GND
GND
3) Power supply sequencing. By connecting a small capacitor from ON/OFF to GND, the 2 μA current source and 1.25 V threshold
can provide a stable and predictable delay between startup of multiple power supplies. For example, a startup delay of roughly 64
ms is provided using C5 100 nF, or roughly 136 ms by using 220 nF.
1
5
P78AS
+Vin
10
C1
+Vout
100 µF
6
7,9
C5
470 pF
GND
GND
C5 220 nF, Power on delay 136 ms
Channel 1 yellow: Voltage on pin 10,
Channel 2 blue: + Vout
Test circuit for output ripple & noise, start up time and load tansient response
25.4
+Vin
P78AS
1
10
7, 9
C1
12.7
Unit:mm
1µ
+Vout
10 µ
Cer.
Cer.
5
6
C2
470
pF
12.7
C3
Oscilloscope
measure points
GND
GND
Page 3 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch
500 mA DC-DC Step Down Converter P78AS-Series
Page 3 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch
500 mA DC-DC Step Down Converter P78AS-Series
Page 4 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch
500 mA DC-DC Step Down Converter P78AS-Series
Dimensions
Pin
1
5
6
7
9
10
Connections
+V Input
+V Output
Trim input
GND
GND
ON/OFF control
PHI-CON is a trademark of HY-LINE Power Components.
Only for professional use by professionals! Not for resale or distribution to the general public in any way! Read the instructions for
use carefully before using!
Life Support Policy: HY-LINE does not authorize the use of any of its products for use in life support devices or systems without
the express written approval of an officer of the Company. Life support systems are devices which support or sustain life, and
whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably
expected to result in significant injury to the user. Rev: 2.14 f
Page 5 of 5
Deutschland:
Inselkammerstraße 10
D-82008 Unterhaching
Tel.: 089 614 503-10
E-Mail: power@hy-line.de
Schweiz:
Gründenstrasse 82
CH-8247 Flurlingen
Tel.: 052 647 42 00
E-Mail: power@hy-line.ch