ST B5973D User Manual
Features
■ Qualified following the AEC-Q100
requirements (temperature Grade 1), see
PPAP for more details.
■ 2 A DC output current
■ Operating input voltage from 4 V to 36 V
■ 3.3 V / (±2 %) reference voltage
■ 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
■ Inhibit for zero current consumption
■ Synchronization
■ Protection against feedback disconnection
■ Thermal shutdown
Applications
■ Dedicated to automotive applications
Figure 1. Typical application
VIN=4V to 35V
VIN=4V to 35V
C1
C1
10uF
10uF
35V
35V
CERAMIC
CERAMIC
C3
C3
220pF
220pF
C4
C4
22nF
22nF
VCC
VCC
COMP
COMP
R3
R3
4k7
4k7
8
8
4
4
VREF
VREF
3.3V
3.3V
6
6
B
A5973D
A5973D
7
7
GND
GND
B5973D
2 A step down switching regulator
for automotive applications
HSOP8 exposed pad
Description
The B5973D is a step down monolithic power
switching regulator with a minimum switch current
limit of 2.25 A so it is able to deliver up to 2 A DC
current to the load depending on the application
conditions. The output voltage can be set from
1.235 V to 35 V. The high current level is also
achieved thanks to an SO8 package with exposed
frame, that allows to reduce the R
approximately 40 °C/W. The device uses an
internal P-channel DMOS transistor (with a typical
R
of 250 mΩ) as switching element to
DSon
minimize the size of the external components. An
internal oscillator fixes the switching frequency at
250 kHz. Having a minimum input voltage of 4V
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. Pulse by pulse current
limit with the internal frequency modulation offers
an effective constant current short circuit
protection.
L1 15uH
L1 15uH
OUT
OUT
1
1
SYNCH
SYNCH
2
INH
INH
2
FB
FB
5
5
3
3
D1
D1
STPS340U
STPS340U
R1
R1
5k6
5k6
R2
R2
3k3
3k3
th(JA)
down to
Vout=3.3V
Vout=3.3V
C2
C2
330uF
330uF
6.3V
6.3V
August 2008 Rev 3 1/11
www.st.com
1
B5973D Contents
Contents
1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1/11
B5973D
1 Pin settings
1.1 Pin connection
Figure 2. Pin connection (top view)
1.2 Pin description
Table 1. Pin description
N° Pin Description
1 OUT Regulator output.
2 SYNCH Master/slave synchronization.
A logical signal (active high) disables the device. If INH not used the pin
3INH
4 COMP E/A output for frequency compensation.
5FB
6 VREF 3.3 V V
7 GND Ground.
8 VCC Unregulated DC input voltage.
must be grounded. When it is open an internal pull-up disable the
device.
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.
REF. No cap is requested for stability.
2/11
Electrical data B5973D
2 Electrical data
2.1 Maximum ratings
Table 2. Absolute maximum ratings
Symbol Parameter Value Unit
V
8
V
1
I
1
V
, V
4
V
3
V
2
P
TOT
T
j
T
STG
Input voltage 40 V
OUT pin DC voltage
OUT pin peak voltage at Δt = 0.1μs
Maximum output current int. limit.
Analog pins 4 V
5
INH -0.3 to V
SYNCH -0.3 to 4 V
Power dissipation at TA ≤ 70 °C 2.25 W
Operating junction temperature range -40 to 150 °C
Storage temperature range -55 to 150 °C
2.2 Thermal data
Table 3. Thermal data
Symbol Parameter SO8 Unit
R
thJA Maximum thermal resistance junction-ambient 40
1. Package mounted on board
-1 to 40
-5 to 40
(1)
CC
V
V
V
°C/W
3/11
Loading...