A6902D
Datasheet
Up to 1 A step down switching regulator with adjustable current limit for
automotive applications
Features
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Qualified following the AEC-Q100 requirements
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
S O-8
Applications
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•
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Automotive applications
Adjustable current generator
Simple step-down converters with adjustable current limit
Description
Maturity status link
A6902D
The
A6902D
is a complete step down switching regulator with adjustable current
limit. Based on a voltage mode structure it integrates an additional current error
amplifier to implement both a constant voltage and constant current control.
The current limit programming is very simple and accurate (± 5%) selecting the
proper sensing resistor.
The DC-DC converter can be used either as a voltage source with adjustable current
limit (set by using the external sense resistor) or as current source to charge NiMH /
NiCd batteries or drive voltage load like LEDs.
The internal P-Channel DMOS transistor (typ. R
DSON
250 mΩ) assures high
efficiency and minimum dropout even at high output current level.
DS5503
-
Rev 6
-
October 2018
For further information contact your local STMicroelectronics sales office.
www.st.com
A6902D
Pin description
1
Pin description
Figure 1.
Pin connection (top view)
OUT
CS+
CS-
COMP
1
2
3
4
8
7
6
5
VCC
GND
VREF
FB
Table 1.
Pin description
Pin n°
1
2
3
4
5
6
7
8
Name
OUT
CS+
CS-
COMP
FB
VREF
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 extenal 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
DS5503
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Rev 6
page 2/33
A6902D
Absolute maximum ratings
2
Absolute maximum ratings
Stressing the device above the rating listed in the table below may cause permanent damage to the device.
These are stress ratings only and operation of the device at these or any other conditions above those indicated
in the operating sections of this specification is not implied.
Exposure to absolute maximum rating conditions may affect device reliability.
Table 2.
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 Δt = 0.1 μs
Maximum output current
Analog pins
Analog pins
Power dissipation at T
A
≤ 70 °C
Operating junction temperature range
Storage temperature range
-40
-55
-0.3
-0.3
Parameter
Min.
-0.3
-1
-5
int. limit.
4
V
CC
0.7
150
150
V
V
W
°C
°C
Max.
40
40
40
Unit
V
V
Table 3.
Thermal data
Symbol
R
thJA
Parameter
Thermal resistance junction to ambient (device soldered
on a standard demonstration board)
SO-8
110
Unit
°C/W
DS5503
-
Rev 6
page 3/33
A6902D
Electrical characteristics
3
Electrical characteristics
T
J
= -40 to 125 °C, V
CC
= 12 V, unless otherwise specified.
Table 4.
Electrical characteristics
Symbol
V
CC
R
DS(on)
I
L
f
SW
Parameter
Operating input voltage range
MOSFET on resistance
Maximum limiting current
Switching frequency
Duty cycle
Dynamic characteristics (see test circuit)
V5
η
Voltage feedback
Efficiency
8 V < V
CC
< 36 V; 20 mA < I
0
< 1 A
V
0
= 5 V, V
CC
= 12 V
DC characteristics
I
qop
I
q
Total operating quiescent
current
Quiescent current
Duty cycle = 0; V
FB
= 1.5 V
Error amplifier
V
OH
V
OL
I
o source
I
o sink
I
b
High level output voltage
Low level output voltage
Source output current
Sink output current
Source bias current
DC open loop gain
gm
V
OFFS
I
CS+
Transconductance
Input offset voltage
CS+ output current
R
L
= ∞
I
COMP
= -0.1 mA to 0.1 mA;
V
COMP
= 1.9 V
V
CS-
= 1.8 V; V
CS+
= V
comp
I
0
=1 A; R
SENSE
= 100 mΩ;
V
OUT
< V
CC
- 2 V
I
0
= 1 A; R
SENSE
= 100 mΩ;
V
OUT
< V
CC
- 2 V
Reference section
Reference voltage
Line regulation
Load regulation
Short circuit current
I
REF
= 0 to 5 mA; V
CC
= 8 V to 36 V
I
REF
= 0 mA; V
CC
= 8 V to 36 V
I
REF
= 0 to 5 mA
5
3.2
3.3
5
8
18
3.399
10
15
35
V
mV
mV
mA
90
50
V
FB
= 1 V
V
FB
= 1.5 V
V
COMP
= 1.9 V; V
FB
= 1 V
V
COMP
= 1.9 V; V
FB
= 1.5 V
160
1
300
1.5
2.5
58
2.3
100
1.5
110
3
4
3.6
0.4
V
V
μA
mA
μA
dB
mS
mV
μA
3
5
2.7
mA
mA
1.198
1.235
90
1.272
V
%
V
CC
= 8.5 V
(1)
V
CC
= 8.5 V, T
J
= 25 °C
1.8
2
212
0
Test conditions
V
0
= 1.235 V; I
0
= 2 A
Min.
8
0.250
2.5
2.5
250
Typ.
Max.
36
0.5
3.2
3.2
280
100
Unit
V
Ω
A
kHz
%
I
CS-
CS- output current
1.5
3
μA
1. With T
J
= 85 °C, I
lim_min
= 2 A, assured by design, characterization and statistical correlation.
DS5503
-
Rev 6
page 4/33
A6902D
Datasheet parameters over the temperature range
4
Datasheet parameters over the temperature range
The 100% of the population in the production flow is tested at three different ambient temperatures (-40 °C; +25
°C, +125 °C) to guarantee the datasheet parameters inside the junction temperature range (-40 °C; +125 °C).
The device operation is so guaranteed when the junction temperature is inside the (-40 °C; +150 °C) temperature
range. The designer can estimate the silicon temperature increase respect to the ambient temperature evaluating
the internal power losses generated during the device operation (please refer to the
Section 8.4 Thermal
considerations).
However the embedded thermal protection disables the switching activity to protect the device in case the junction
temperature reaches the T
SHTDWN
(+150 °C ± 10 °C) temperature.
All the datasheet parameters can be guaranteed to a maximum junction temperature of +125 °C to avoid
triggering the thermal shutdown protection during the testing phase because of self-heating.
DS5503
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Rev 6
page 5/33
