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R5972D Schematic ( PDF Datasheet ) - STMicroelectronics

Teilenummer R5972D
Beschreibung Up to 1.5A step-down switching regulator
Hersteller STMicroelectronics
Logo STMicroelectronics Logo 




Gesamt 30 Seiten
R5972D Datasheet, Funktion
R5972D
Up to 1.5 A step-down switching regulator for aerospace
applications
Datasheet - preliminary data
– Advanced mold and frame designs for
superior resilience in harsh environments
(acceleration, EMI, thermal, humidity)
– Extended screening capability on request
Application
SO-8
Dedicated to aerospace applications
Features
General features
– 1.5 A DC output current
– Operating input voltage from 4 V to 36 V
– 3.3 V / (± 2%) reference voltage
– Large ambient temperature range:
-40 °C to 125 °C
– Output voltage adjustable from 1.235 V to
VIN
– Low dropout operation: 100% duty cycle
– 250 kHz internally fixed frequency
– Voltage feed-forward
– Zero load current operation
– Internal current limiting
– Inhibit for zero current consumption
– Protection against feedback disconnection
– Thermal shutdown
Aerospace and defense features
– Suitable for use in aerospace and defense
applications
– Dedicated traceability and part marking
– Production parts approval documents
available
– Adapted extended life time and
obsolescence management
– Extended product change notification
process
– Designed and manufactured to meet sub-
ppm quality goals
Description
The R5972D is a step-down monolithic power
switching regulator with a minimum switch current
limit of 1.8 A so it is able to deliver up to 1.5 A DC
current to the load depending on the application
conditions. The output voltage can be set from
1.235 V to VIN.
The device uses an internal P-channel DMOS
transistor (with a typical RDS(on) of 250 m) as
a switching element to minimize the size of the
external components.
An internal oscillator fixes the switching frequency
at 250 kHz. The large ambient temperature range
makes it ideal for aerospace and defense
applications. A pulse-by-pulse current limit with
the internal frequency modulation offers an
effective constant current short-circuit protection.
October 2014
DocID026873 Rev 1
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.
1/35
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R5972D Datasheet, Funktion
Electrical characteristics
3 Electrical characteristics
R5972D
TJ = -40 °C to 125 °C, VCC = 12 V, unless otherwise specified.
Symbol
Table 4. Electrical characteristics
Parameter
Test condition
Min. Typ. Max.
VCC
RDS(on)
Operating input voltage range
MOSFET on resistance
IL Maximum limiting current(1)
fSW Switching frequency
Duty cycle
VCC = 5 V
VCC = 5 V, TJ = 25 °C
4
1.8
2
212
0
Dynamic characteristics (see test circuit)
V5 Voltage feedback
Efficiency
DC characteristics
4.4 V < VCC < 36 V
V0 = 5 V, VCC = 12 V
1.198
Iqop Total operating quiescent current
Iq Quiescent current
Error amplifier
Duty cycle = 0; VFB= 1.5 V
VOH High level output voltage
VOL Low level output voltage
VFB = 1 V
VFB = 1.5 V
3.5
Io source Source output current
VCOMP = 1.9 V; VFB = 1 V
190
Io sink
Ib
Sink output current
Source bias current
VCOMP = 1.9 V; VFB = 1.5 V
1
DC open loop gain
RL =
50
gm Transconductance
ICOMP = -0.1 mA to 0.1 mA;
VCOMP = 1.9 V
1. With TJ = 85 °C, Ilim_min = 2 A, assured by design, characterization and statistical correlation.
0.250
2.5
2.5
250
1.235
90
3
300
1.5
2.5
65
2.3
36
0.5
3
3
280
100
1.272
5
2.5
0.4
4
Unit
V
A
kHz
%
V
%
mA
mA
V
V
A
mA
A
dB
mS
6/35 DocID026873 Rev 1

6 Page









R5972D pdf, datenblatt
Additional features and protection
6 Additional features and protection
R5972D
6.1 Feedback disconnection
If the feedback is disconnected, the duty cycle increases towards the maximum allowed
value, bringing the output voltage close to the input supply. This condition could destroy the
load.
To avoid this hazardous condition, the device is turned OFF if the feedback pin is left
floating.
6.2 Output overvoltage protection
Overvoltage protection, or OVP, is achieved by using an internal comparator connected to
the feedback, which turns OFF the power stage when the OVP threshold is reached. This
threshold is typically 30% higher than the feedback voltage.
When a voltage divider is required to adjust the output voltage (Figure 13 on page 24), the
OVP intervention will be set at:
Equation 1
VOVP = 1.3 -R----1--R--+---2--R-----2- VFB
Where R1 is the resistor connected between the output voltage and the feedback pin, and
R2 is between the feedback pin and ground.
6.3 Zero load
Due to the fact that the internal power is a PDMOS, no boostrap capacitor is required and so
the device works properly even with no load at the output. In this case it works in burst
mode, with a random burst repetition rate.
12/35
DocID026873 Rev 1

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