Technical Reference Notes
ALO25F24
(Single Output 8
th
Brick)
ALO25F24 Single Output 8
th
Brick: Open-Frame Module
The ALO25F24 is Astec’s 8
th
Brick industry standard offering. Operating from an input voltage range of 18V to 36V. It
delivers up to 25A max current at 3.3V output voltage. It provides tight regulation and exhibits clean and monotonic output
start up characteristics. This model comes with industry standard features such as Input UVLO; Enable On/Off, OCP, OVP and
OTP; Output Trim; Differential Remote Sense pins. Open frame construction is available with TH and SMT termination. With
its wide operating temperature range of -40°C to 85°C ambient, the converter is deployable into almost any environment.
Electrical Parameters
Input
Input Range
Input Surge
18-36 VDC
50V / 100ms
Control
Enable
TTL compatible
(Positive or Negative Logic Enable Options)
Output
Load Current
Line/Load Regulation
Ripple and Noise
Output Voltage
Adjust Range
Transient Response
3.3V @ 25A max (P
O
= 82.5W)
< 1% V
O
75mV
P-P
±10% V
O
5% Typical deviation
50% to 75% Load Change
100µs settling time (Typ)
µ
+10%V
O
120% (Typ)
130% (Typ)
103°C
°
Special Features
•
•
•
•
•
•
•
•
Industry Standard 8
th
Brick Footprint
Open frame construction
Low Ripple and Noise
Regulation to zero load
High Capacitive Load Start-up
Fixed Switching Frequency
Industry standard features: Input UVLO;
Enable; OVP, OCP and OTP; Output Trim,
Remote Sense
Meets Basic Insulation
Remote Sense
Over Current
Protection
Over Voltage
Protection
Over Temperature
Protection
Environmental Specifications
•
•
•
-40ºC to 85ºC Operating Temperature
-40ºC to 125ºC Storage Temperature
MTBF > 1 million hours
Safety
UL + cUL 60950, Recognized
EN60950 through TUV-PS
MODEL: ALO25F24
AUGUST 23, 2005 - REVISION H
SHEET 1 OF 13
Technical Reference Notes
ALO25F24
(Single Output 8
th
Brick)
Electrical Specifications
ABSOLUTE MAXIMUM RATINGS
Stresses in excess of the absolute maximum ratings can cause permanent damage to the converter. Functional
operation of the device is converter is not implied at these or any other conditions in excess of those given in the
operational section of the specs. Exposure to absolute maximum ratings for extended period can adversely affect
device reliability.
Parameter
Input Voltage
Continuous
Transient (100ms)
I/O Isolation
(Conditions 50µA for 5 sec, slew
rate of 1500V/10sec)
Input-to-Output
Operating Temperature
Storage Temperature
Operating Humidity
Max Voltage at Enable Pin
Max Output Power
All
All
All
All
All
All
-
T
A
T
STG
-
P
O,MAX
-
-40
-40
10
-
-
-
-
-
-
-
-
1500
85
125
85
25
82.5
Vdc
ºC
ºC
%
Vdc
W
Device
All
Symbol
Vin
Vin
trans
Min
-
-
Typical
-
-
Max
36
50
Unit
Vdc
INPUT SPECIFICATIONS
Parameter
Operating Input Voltage Range
Input Under-Voltage Lock-out
T_ON Threshold
T_OFF Threshold
Input Line Drop Out Time (25°C)
- within overshoot spec
- within 450mV overshoot
Max Input Current
1
(V
IN
= V
IN, Min
; I
O
= I
O, Max
)
Max P
diss
@ I
O
= 0A
(V
IN
= V
IN, Nom
)
Temperature: T
A
= 25°C
Input Ripple Current
2
5Hz to 20MHz
Input Voltage Rise Time
10% to 90% of Vout
Inrush Current
dI
IN
/dt
Device
All
All
Symbol
V
IN
Min
18
17.2
15.8
All
All
All
All
V
IN
V
IN
Iin
max
5
1
-
-
Typical
24
-
-
-
-
-
-
Max
36
17.95
16.50
-
-
6.0
4.6
Unit
Vdc
Vdc
ms
A
W
All
All
All
I
I1
-
-
-
6
-
-
-
1.7
5
mAp-p
V/ms
A
pk
MODEL: ALO25F24
AUGUST 23, 2005 - REVISION H
SHEET 2 OF 13
Technical Reference Notes
ALO25F24
(Single Output 8
th
Brick)
Electrical Specifications (continued)
OUTPUT SPECIFICATIONS
Parameter
Output Voltage Set point
V
IN
= V
IN, Min
to V
IN, Max
I
O
= I
O, Max
Output Regulation
Line
V
IN
= V
IN, Min
to V
IN, Max
Load
I
O
= I
O, Min
to I
O, Max
Temperature:
T
A
= -40°C to 85°C
Output Ripple and Noise
3
Peak-to-Peak: (5Hz to 20MHz)
External Load Capacitance
Capacitor ESR
Output Current
4
Output Current-limit Inception
V
OUT
= 90% V
O, Set
;
T
A
= 25°C
Output Over Voltage Protection
Over Temperature Protection
(AVG. PCB TEMP)
Device
All
Symbol
V
O, SET
Min
3.24
Typical
3.30
Max
3.35
Unit
Vdc
All
-
-
-
-
-
-
-
-
15
0
26.5
-
-
-
40
-
-
-
-
±
0.20
±
0.20
±
1.00
75
15,000
-
25
35
%
All
All
All
All
-
-
I
O
I
O
mVp-p
µF
mΩ
A
A
All
All
All
V
O
η
-
-
3.9
103
87
4.1
-
88
4.9
117
-
V
°C
%
Efficiency
V
IN
= V
IN, Nom
; I
O
= I
O, Max
T
A
= 25ºC
Turn On Response Time
V
IN
= V
IN, Min
toV
IN, Max
Enable to Output Turn-On Delay
V
IN
= V
IN, Min
toV
IN, Max
I
O
= I
O, Min
to I
O, Max
+ V
IN
to Output Turn-On Delay
Enable Pin: Active
V
IN
= V
IN, Nom
I
O
= I
O, Max
Switching Frequency
Output Voltage Remote Sensing
Output Voltage Trim Range
5
Output Enable ON/OFF
6
Enable Signal Slew Rate
Negative Enable (“N” suffix)
Enable Pin Voltage: Mod-ON
Mod-OFF
Positive Enable (No suffix)
Enable Pin Voltage: Mod-ON
Mod-OFF
MODEL: ALO25F24
AUGUST 23, 2005 - REVISION H
All
All
-
-
-
-
15
15
ms
ms
All
-
-
-
15
ms
All
All
All
All
-
-
580
-
90
0.01
0
2.95
660
-
740
10
110
-
0.8
20
kHz
%V
O
%V
O
V/ms
V
V
-
-
-
-
-
-
-
-
2.95
0
-
-
20
0.8
V
V
SHEET 3 OF 13
Technical Reference Notes
ALO25F24
(Single Output 8
th
Brick)
Electrical Specifications (continued)
OUTPUT SPECIFICATIONS
Parameter
Dynamic Response
C
O
= 0µF
Peak Deviation
Load Change from I
O
= 50% to
75% of I
O, Max
:
Settling Time to V
O, Set
Tolerance
Peak Deviation
Load Change from I
O
= 50% to
25% of I
O, Max
:
Settling Time to V
O, Set
Tolerance
Output Overshoot
At T-on / t-off
Passive Resistive Full Load
T < 0°C
Device
∆I
O
/∆t
All
Symbol
-
-
-
-
Min
-
-
-
-
Typical
0.1
5
100
300
Max
-
Unit
A/µs
%V
O
µs
%V
O
300
3
µs
%V
O
%V
O
All
All
All
-
-
-
-
-
-
-
-
-
-
5
100
-
-
-
-
-
4
Note: 1. The converter is not internally fused. An input line fuse such as Littlefuse 3AB type must be used.
2. Refer to Figure 1 for the external input capacitance required.
3. Refer to Figure 2 for output ripple and noise test measurement setup.
4. Output power derating applies at elevated temperature. Refer to Figure 11.
5. Refer to the output trim equations provided (Equations 1 and 2).
6. For temperature greater than -20°C, minimum pin disable time is 100ms.
For temperature less than -20°C, minimum pin disable time is 1s.
SAFETY AGENCY / MATERIAL RATING / ISOLATION
Parameter
Safety Approval
Material Flammability Rating
Parameter
Input to Output Capacitance
Input to Output Resistance
Input to Output Insulation Type
Device
All
All
Device
All
All
All
UL/cUL 60950, 3rd Edition – Recognized
EN 60950 through TUV
UL94V-0
Symbol
Min
Typical
Max
-
1000
-
-
TBD
-
-
Basic
-
Unit
pF
Ohms
-
MODEL: ALO25F24
AUGUST 23, 2005 - REVISION H
SHEET 4 OF 13
Technical Reference Notes
ALO25F24
(Single Output 8
th
Brick)
Electrical Specifications (continued)
TO OSCILLOSCOPE
Ltest
12 uH
BATTERY
Cs 220 uF
ESR < 0.1 OHM
@ 20 ºC, 100 kHz
33 uF
ESR < 0.7 OHM
@ 20 ºC, 100 kHz
Vi(+)
Vi(-)
Measure input reflected-ripple current with a simulated source inductance (Ltest) of
12uH. Capacitor Cs offsets possible battery impedance. Measure current as shown
above.
Figure 1. Input Reflected Ripple Current Measurement Setup.
COPPER STRIP
Vo(+)
0.1 uF
Vo(-)
10 uF SCOPE
RESISTIVE
LOAD
Use a 0.1µF @50V X7R ceramic capacitor (connected an inch away from the output
terminals of the UUT) and a 10µF @ 25V tantalum capacitor (2 inches away from
the output terminals of the UUT). Scope measurement should be made using a BNC
socket, positioned 3 inches away from output terminals of the converter.
Figure 2. Peak to Peak Output Noise Measurement Setup.
MODEL: ALO25F24
AUGUST 23, 2005 - REVISION H
SHEET 5 OF 13
