R6902D
Up to 1 A step-down switching regulator with adjustable current limit
for aerospace applications
Datasheet
-
preliminary data
SO-8
Features
General features
– Up to 1 A DC output current
– Operating input voltage from 8 V to 36 V
– Output voltage adjustable from 1.235 V to
35 V
– Precise 3.3 V (± 2%) reference voltage
– 250 kHz internally fixed frequency
– Voltage feedforward
– Zero load current operation
– Internal current limiting
– 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
– Advanced mold and frame designs for
superior resilience in harsh environments
(acceleration, EMI, thermal, humidity)
– Extended screening capability on request
Applications
Aerospace applications
Adjustable current generator
Simple step-down converters with adjustable
current limit
Figure 1. Application schematic
October 2014
DocID026994 Rev 1
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This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.
Contents
R6902D
Contents
1
2
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
2.2
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1
3.2
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
5
6
7
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
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DocID026994 Rev 1
R6902D
Description
1
Description
The R6902D is a complete and simple step-down switching regulator with an adjustable
current limit. Based on a voltage mode structure it integrates a current error amplifier to
have a constant voltage and constant current control. By means of an on-board current
sense resistor and the availability of the current sense pins (both compatible to Vcc and for
Cs- compatible with GND too) current limit programming is very simple and accurate.
Moreover constant current control can be used to charge NiMH and NiCd batteries. The
device can be used as a standard DC/DC converter with the adjustable current limit (set by
using the external sense resistor). The internal robust P-channel DMOS transistor with
a typical of 250 m assures high efficiency and a minimum dropout even at a high output
current level. The internal limiting current (latched function) of typical value of 2.5 A protects
the device from an accidental output short-circuit avoiding dangerous loads damage. If the
temperature of the chip goes higher than a fixed internal threshold (150 °C with 20 °C
hysteresis), the power stage is turned off. The large ambient temperature range makes it
ideal for aerospace and defense applications.
Other protections beside the thermal shutdown complete the device for a safe and reliable
application: overvoltage protection, frequency foldback overcurrent protection and
protection vs. feedback disconnection. The internal fixed switching frequency of 250 kHz,
and the SO-8 package pin allow to built an ultra compact DC/DC converter with a minimum
board space.
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Pin connection
R6902D
2
2.1
Pin connection
Pin connection
Figure 2. Pin connection (top view)
2.2
Pin description
Table 1. Pin description
No.
1
2
3
4
5
6
7
8
Pin
OUT
CS+
CS-
COMP
FB
V
REF
GND
VCC
Regulator output.
Current error amplifier input (current sense at higher voltage)
Current error amplifier input (current sense at lower voltage)
E/A output for frequency compensation.
Feedback input. Connecting directly to this pin results in an output
voltage of 1.23 V. An external resistive divider is required for higher
output voltages.
3.3 V reference voltage. No cap is need for stability.
Ground.
Unregulated DC input voltage.
Description
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R6902D
Electrical data
3
3.1
Electrical data
Maximum ratings
Table 2. Absolute maximum ratings
Symbol
V
8
V
1
I
1
V
4
, V
5
V
2
, V
3
P
TOT
T
J
T
STG
Input voltage
OUT pin DC voltage
OUT pin peak voltage at
t
= 0.1
s
Maximum output current
Analog pins
Analog pins
Power dissipation at T
A
70 °C
Operating junction temperature range
Storage temperature range
Parameter
Value
40
-1 to 40
-5 to 40
Int. limit.
4
-0.3 to V
CC
0.7
-40 to 150
-55 to 150
V
V
W
°C
°C
Unit
V
V
V
3.2
Thermal data
Table 3. Thermal data
Symbol
R
thJA
Parameter
Maximum thermal resistance junction ambient
SO-8
110
(1)
Unit
°C/W
1. Package mounted on board.
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