STMICROELECTRONICS A5972D_0808

A5972D
Up to 1.5 A step down switching regulator
for automotive applications
Features
■
Qualified following the AEC-Q100
requirements (temperature grade 3), see PPAP
for more details.
■
1.5 A DC output current
■
Operating input voltage from 4 V to 36 V
■
Output voltage adjustable from 1.235 V to 35 V
■
Low dropout operation: 100 % duty cycle
■
250 kHz Internally fixed frequency
■
Voltage feedforward
■
Zero load current operation
■
Internal current limiting
■
Protection against feedback disconnection
■
Thermal shutdown
SO-8
Description
The A5972D is a step down monolithic power
switching regulator with a minimum switch current
limit of 1.8 A so it is able to deliver more than
1.5 A DC current to the load depending on the
application conditions.
The output voltage can be set from 1.235V to 35V.
The device uses an internal P-channel D-MOS
transistor (with a typical RDS(on) of 250 mΩ) as
switching element to minimize the size of the
external components.
Applications
■
An internal oscillator fixes the switching frequency
at 250 kHz.
Automotive applications
Having a minimum input voltage of 4 V only, it is
particularly suitable for 5 V bus.
Pulse by pulse current limit with the internal
frequency modulation offers an effective constant
current short circuit protection.
Figure 1.
Application schematic
33uH
VIN=4.4V to 35V
VCC
COM P
C4
22nF
C1
A5972D
D1
STPS2L40U
10uF
VO UT=3.3V
OUT
GND
R1
C2
100uF
5.6K
FB
C3
220pF
4.7KΩ
R2
R3
August 2008
3.3K
Rev 4
1/11
www.st.com
1
A5972D
Contents
Contents
1
2
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2/11
A5972D
1
Pin settings
1.1
Pin connection
Figure 1.
1.2
Pin connection (top view)
Pin description
Table 1.
Pin description
N°
Pin
Description
1
OUT
Regulator output.
2,3,6,7
GND
Ground.
4
COMP
5
FB
8
VCC
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.
Unregulated DC input voltage.
3/11
Electrical data
A5972D
2
Electrical data
2.1
Maximum ratings
Table 2.
Absolute maximum ratings
Symbol
Unit
40
V
V
V
Input voltage
V1
OUT pin DC voltage
OUT pin peak voltage at Δt = 0.1 μs
-1 to 40
-5 to 40
I1
Maximum output current
int. limit.
PTOT
TJ
TSTG
Analog pins
4
V
1.2
W
Operating junction temperature range
-40 to 150
°C
Storage temperature range
-55 to 150
°C
SO8
Unit
(1)
°C/W
Power dissipation at TA ≤ 70 °C
Thermal data
Table 3.
Thermal data
Symbol
RthJA
Parameter
Maximum thermal resistance junction-ambient
1. Package mounted on board
4/11
Value
V8
V4 , V5
2.2
Parameter
65
A5972D
Electrical characteristics
Table 4.
Electrical characteristics
(TJ = -40 to 125 °C, VCC = 12 V, unless otherwise specified)
Symbol
VCC
RDS(on)
IL
fSW
Parameter
Operating input
voltage range
Test condition
V0 = 1.235 V; I0 = 2 A
Min
Max
Unit
Maximum limiting
current (1)
VCC = 5 V
VCC = 5 V, TJ = 25 °C
Switching frequency
Duty cycle
Typ
36
V
0.250
0.5
Ω
1.8
2.5
3
2
2.5
3
212
250
280
kHz
100
%
1.272
V
4
Mosfet on resistance
A
0
Dynamic characteristics (see test circuit)
V5
Voltage feedback
4.4 V < VCC < 36 V,
20 mA < I0 < 2 A
η
Efficiency
V0 = 5 V, VCC = 12 V
1.198
1.235
90
%
DC characteristics
Iqop
Total operating
quiescent current
Iq
Quiescent current
3
Duty cycle = 0; VFB= 1.5 V
5
mA
2.5
mA
Error amplifier
VOH
High level output
voltage
VFB = 1 V
VOL
Low level output
voltage
VFB = 1.5 V
Io source
Source output current
Io sink
Sink output current
Ib
Source bias current
3.5
V
0.4
190
300
μA
1
1.5
mA
VFB = 1 V
VCOMP = 1.9 V;
V
VFB = 1.5 V
DC open loop gain
gm
VCOMP = 1.9 V;
Transconductance
2.5
RL=
8
3
ICOMP = -0.1 mA to 0.1 mA;
50
4
μA
65
dB
2.3
mS
VCOMP = 1.9 V
1. With TJ = 85 °C, Ilim_min = 2 A, assured by design, characterization and statistical correlation.
5/11
Typical characteristics
4
6/11
A5972D
Typical characteristics
Figure 2.
Output voltage vs junction
temperature
Figure 3.
Quiescent current vs junction
temperature
Figure 4.
Line regulatior
Figure 5.
Shutdown current vs junction
temperature
Figure 6.
Output voltage vs junction
temperature
Figure 7.
Junction temperature vs
output current
A5972D
Figure 8.
Junction temperature vs
output current
Figure 9.
Efficiency vs output current
Figure 10. Efficiency vs output current
7/11
Package mechanical data
5
A5972D
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect . The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
8/11
A5972D
Table 5.
SO-8 mechanical data
mm
inch
Dim
Min
Typ
Max
Min
Typ
Max
A
1.35
1.75
0.053
0.069
A1
0.10
0.25
0.004
0.010
A2
1.10
1.65
0.043
0.065
B
0.33
0.51
0.013
0.020
C
0.19
0.25
0.007
0.010
D (1)
4.80
5.00
0.189
0.197
E
3.80
4.00
0.15
0.157
e
1.27
0.050
H
5.80
6.20
0.228
0.244
h
0.25
0.50
0.010
0.020
L
0.40
1.27
0.016
0.050
k
ddd
0° (min), 8° (max)
0.10
0.004
1. Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs
shall not exceed 0.15mm (0.006 inch) in total (both side).
Figure 11. SO-8 mechanical data
9/11
Revision history
6
A5972D
Revision history
Table 6.
10/11
Document revision history
Date
Revision
Changes
06-Aug-2007
1
Initial release
5-Nov-2007
2
Updated: Table 4 on page 5
2-May-2008
3
Updated: Cover page, Table 4 on page 5
27-Aug-2008
4
Updated: Coverpage and Table 4 on page 5
A5972D
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