PTB78520W Datasheet, PDF (1/15 Pages) Texas Instruments – 20-A, 18–60-V Input Auto-Track Compatible Isolated DC/DC Converter

PTB78520W
Not Recommended for New Designs
20-A, 18–60-V Input Auto-Track
Compatible Isolated DC/DC Converter
SLTS226A – JULY 2004 – REVISED OCTOBER 2005
Features
• Wide-Input Voltage Range:
18 V to 60 V
• Auto-Track Compatible
Sequenced Output
• 20 A Total Output Current
• Smart-Sense Remote Sensing
• 90% Efficiency
• Wide-Adjust Output Voltage:
1.8 V to 3.6 V
• Under-voltage Lockout
• Industry Standard Footprint
• Surface Mountable
• Over-Current Protection
• 1500 VDC Isolation
• Output Over-Voltage Protection • Agency Approvals (Pending):
• Over-Temperature Shutdown
UL/cUL 60950, EN 60950
• Output Enable Control
Description
The PTB78520W is a 20-A rated,
wide-input (18-60 V) isolated DC/DC
converter that incorporates Auto-Track™
power-up sequencing. This allows these
modules to simultaneously power up with
any other downstream non-isolated, Auto-
Track compliant module.
The PTB78520W module provides
two outputs, each regulated to the same
voltage. During power up, the voltage at
‘V_O Bus’ rises first, allowing this output
to provide input power to any downstream
non-isolated module. The voltage from
‘V_O Seq’ is then allowed to rise simulta-
neously, under the control of Auto-Track,
along with the outputs from the down-
stream modules.
Whether used to facilitate power-up
sequencing, or operated as a stand-alone
module, the PTB78520W includes many
features expected of high-performance
DC/DC converter modules. The combi-
Typical Application
nation of input-output isolation and a
wide-input voltage range, allows operation
from either +24 V or –48 V. The wide-
output adjust enables the output voltage
to be set to to any voltage over the range,
1.8 V to 3.6 V, using a single external
resistor. Precise output voltage regula-
tion is assured using Smart-Sense. This
is a differential remote sense that will
intelligently regulate the sequenced out-
put, depending on its sequence status.
Other operational features include an
input under-voltage lockout (UVLO) and
an output enable control. Over-current,
over-voltage, and over-temperature pro-
tection assures the module’s ability to
survive any load fault.
Typical applications include distributed
power architectures in both telecom and
computing environments, particularly
complex digital systems requiring power-
sequencing of multiple power supply rails.
Pin-Out Information
Pin Function
1 +V_IN
2 V_O Enable *
3 –V_IN
4 Track
5 V_O Com
6 (–) Sense
7 Vo Adjust
8 (+) Sense
9 V_O Bus
10 V_O Seq
Shaded functions indicate signals
electrically common with the input.
* Denotes negative logic:
Low (–V_IN) = Normal operation
Open = Output off
AuSteoq-Tureanccki™ng
4
Track
PTB78520W
Simultaneous Powerup
V1
V2
8
+Sense
10
+VI
1
VO Seq
+VI
9
VO Bus
V1 =3.3 V
2
VO Enable
7
VO Adjust
2
Track
3 _{VI PTH03050W VO} 6
V2 =1.8 V
5
VO COM
RSET
887
Inhibit GND Adjust
–VI
3
6
–VI
–Sense
C1
100 µF
4
15
R1
C2
100 µF
5.49 k
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