Very High Efficiency DC/DC Converter
24/48V Input, 1.5V, 1.8V, 2.0V, 2.5V, 3.3V DC, 30A Output
or 5.0V DC, 20A Output
PISCES Series
The Pisces Series is the first high-efficiency
quarter brick
CoolConverter
™
in the Galaxy
family of high-efficiency DC/DC converters.
Industry Standard Pinout and Footprint
Typical Efficiency
92% at 3.3V, 15A; 90% at 3.3V, 30A
No Heat Sink Required
Very Low Common-mode Noise for a
Commercial DC/DC Converter
Two-stage Input Filter
Constant Switching Frequency
Remote Sense
Single Board Design
Optional Baseplate or Low Profile Heatsink for
Improved Thermal Performance
Header with M3 Metal Inserts for Mechanical
Connection to PCB
Two Year Warranty
The open-frame Pisces is available with an optional
baseplate or low profile heatsink for maximum
thermal performance.
Control Functions
Uses Patented Power Supply Control
and Architecture
Microprocessor Controlled
Primary-side Enable, Choice of Logic
Protection Features
Over Temperature Protection
Over Voltage Protection
Over Current Protection
Over/Under Input Voltage Protection
Typical Characteristics
Output Setpoint Accuracy:
±1%
Load Regulation:
±0.2%
Line Regulation:
±0.2%
Regulation over Line, Load, and Temperature:
±2%
Low Output Ripple
Output Trim
Pisces Series, Page 1
WWW.GALAXYPWR.COM
Part No. 99-002 Rev. 4.0–093003
General Specifications
V
IN
= 48V
DC
, T
A
@25
°
C, 300 LFM Airflow, V
OUT
=3.3V, I
OUT
= Full Load unless otherwise noted.
Available output power depends on ambient temperature and good thermal management. (See application graphs for limits.)
Input Characteristics
Parameter
Min
Typ
Max
Units
Operating Input Voltage
Input Current (Model Dependent)
Input Capacitance
Input Hysteresis, Low Line
Output Characteristics
Regulation Over Line, Load & Temperature
Voltage Ripple
Voltage Ripple, 20MHz BW
Current Range
Current Limit Inception
Short Circuit Current, Peak (see Note below)
Output Transient Response, 50% to 75% load change, 1A/µsec
Settling Time to
±1%
Turn-on Time to 98%Vnom
Output Overshoot at Turn-on
Trim Range
Overvoltage Protection, Latching
Isolation
Isolation Test Voltage, Input/Output (Basic)
Isolation Resistance
Features
Overtemperature Protection, Thermal Sensor, Latching*
Switching Frequency, Fixed
36
48
4.5
2
75
5
V
DC
A
µF
V
DC
98
102
20
150
%V
NOM
mV
RMS
mV
P–P
A
A
A
%V
OUT
µS
mS
%V
OUT
%V
OUT
%V
OUT
V
DC
MΩ
0
31
30
37
41
5
300
35
1
90
130
2000
10
110
117
200
°C
kHz
Notes: During short circuit, converter will shut down and attempt to restart once per second. The average current during this
condition will be very low and the device can be safely left in this condition continuously. For specific output voltage
specifications, see the corresponding detailed data sheet.
*PCB less than 130
°
C
General Specifications
Operating Temperature
Storage Temperature
Relative Humidity
Vibration
Material Flammability
Weight
MTBF
Telcordia (Bellcore)
-40°C to +100°C
-55°C to +125°C
10% to 95% RH,
Non-condensing
2 to 9Hz, 3mm disp.,
9 to 200Hz 1g
UL V-0
35 grams
1,600,000 hours
Approvals and Standards
UL and c-UL Recognized Component, TUV,
UL60950, CSA 22.2 No. 950, IEC/EN 60950**
EMC Characteristics:
Designed to meet emission and immunity
requirements per EN55022, CISPR 22, Class B,
and CISPR 24.
** An external fuse shall be used to comply with the
requirements.
Pisces Series, Page 2
WWW.GALAXYPWR.COM
Part No. 99-002 Rev. 4.0–093003
Application Notes
CoolConverter
™
Galaxy’s proprietary
CoolConverter
™
provides:
• Patented single-stage power conversion architecture,
control, and magnetic design allow unprecedented power
density and efficiency in an isolated power supply.
• An advanced microcontroller reduces parts count while
adding features, performance, and flexibility in the design.
• Low common-mode noise as a result of lower capacitance
in the transformer compared to planar magnetics and
metal baseplate designs.
• Higher reliability than planar transformer designs that can
suffer from via fatigue from thermal cycling, and metal
baseplate designs with board to board interconnects that
are subject to mechanical stress on electrical connections.
Protection and Control
Valid Input Voltage Range:
The converter measures the input voltage and will not
allow operation outside of the input voltage
specification. As shown by the graphs, hysteresis is
added to both the high and low voltage to prevent the
converter from turning on and off repeatedly when the
voltage is held near either voltage extreme. At low line
this assures the maximum input current is not exceeded;
at high line this assures the semiconductor devices in
the converter are not damaged by excessive voltage
stress.
Overvoltage Lockout
Input Current
Voltage
Rising
Voltage
Falling
75
76
77
78
79
80
Input Voltage (V)
ON/OFF Logic Option:
The ON/OFF control logic can be either Negative
(standard) or Positive to enable the converter. For
Negative logic, the ON/OFF pin is brought below 1.0 V
with respect to the –INPUT pin to enable the converter.
The pull down must be able to sink 100µA. For
Positive logic, the ON/OFF pin is brought to greater
than 4.0V with respect to the –INPUT pin and be
limited to less than 10V. To request the Positive logic
version, add the suffix (P) to the standard part number.
The ON/OFF pin has a built-in pull up resistor of
approximately 100kΩ to +5V.
Undervoltage Lockout
Input Current
Voltage
Rising
Voltage
Falling
30
32
34
36
38
40
Input Voltage (V)
Pisces Series, Page 3
WWW.GALAXYPWR.COM
Part No. 99-002 Rev. 4.0–093003
Application Notes
Output Over Voltage Protection:
The output voltage is constantly monitored by the
microprocessor and a redundant secondary-side crowbar
circuit that is set to a higher trip point than the
microprocessor protection. If the output voltage
exceeds the over-voltage specification, the
microprocessor will latch the converter off. To turn the
converter on requires either cycling the ON/OFF pin or
power to the converter. This advanced feature prevents
the converter from damaging the load if there is a
converter failure or application error. If non-latching is
required, consult factory.
Trim:
To trim the output voltage higher, connect the
required trim resistor from the Trim pin to the +Sense
pin. To trim the output voltage lower, connect the
required trim resistor from the Trim pin to the –Sense
pin. See diagram below.
Trim-down
Thermal Shutdown:
The printed circuit board temperature is measured
using a semiconductor sensor. If the maximum rated
temperature is exceeded, the converter is latched off.
To re-enable the converter requires cycling the ON/OFF
pin or power to the converter. If non-latching is
required, consult factory.
Trim-down (%)
Control Options:
As the behavior of the circuit is determined by
firmware in the microcontroller, specific customer
requirements such as
• non-latching thermal protection
• custom valid input voltage range
• controlled delay from initiating an ON/OFF
signal for power sequencing
can be accomplished with no change to hardware.
The standard behavior was chosen based on system
design experience but we understand that customers
often have their own requirements.
Please consult Galaxy Power for your special needs.
R
TRIM-DOWN
=
{
100
–2
∆%
}
5.11kΩ
Trim-up (for 3.3V)
Remote Sense:
The output voltage is regulated at the point where the
sense pins connect to the power output pins. Total
sense compensation should not exceed 0.4V or 10% of
Vout, whichever is greater.
R
TRIM-UP
=
{
Vo (100+∆%) (100+2∆%)
−
1.225∆%
∆%
}
5.11kΩ
Safety:
An external input fuse must always be used to meet
these safety requirements.
External Output Trimming
+ Sense
Trim
– Sense
Pisces Series, Page 4
WWW.GALAXYPWR.COM
Part No. 99-002 Rev. 4.0–093003
GHPW3V3–30 Operation
Efficiency
94
92
14
Power Dissipation
Power Dissipation (W)
12
10
8
6
4
2
0
Efficiency (%)
90
88
86
84
82
80
0
5
10
15
20
25
30
36V Vin
48V Vin
75V Vin
36V Vin
48V Vin
75V Vin
0
5
10
15
20
25
30
Output Current (A)
Load Current (A)
Output Voltage vs Line Load
3.5
Output Voltage (V)
3.0
2.5
2.0
1.5
1.0
0.5
0
28
30
32
34
36
38
40
42
36V Vin
48V Vin
75V Vin
Output Current (A)
Transient Response
Voltage Ripple
V
OUT
V
OUT
20
I
OUT
10
Start-up Waveform w/No Load
[
T
T
Thermal Derating Curves
35
]
30
V
OUT
Iout (A)
25
20
300 LFM, Low Profile Heat Sink
300 LFM, Metal Plate
200 LFM, Low Profile Heat Sink
300 LFM, Open Frame
5
200 LFM, Metal Plate
200 LFM, Open Frame
0
2
15
ON/OFF
10
1
Ch1
5.00V
Ch2
1.00 V
M 4.00ms A
Ch1
2.40V
20
30
40
50
60
70
80
Ambient Air Temperature (deg C)
Pisces Series, Page 5
WWW.GALAXYPWR.COM
Part No. 99-002 Rev. 4.0–093003
