a8447 Allegro MicroSystems, Inc., a8447 Datasheet - Page 4

• Manufacturer Part Number: a8447
• Description: A8447 High-voltage Step-down Regulator
• Manufacturer: Allegro MicroSystems, Inc.

A8447
ELECTRICAL CHARACTERISTICS
1
2
3
Negative current is defined as coming out of (sourcing) the specified device pin.
Specifications over the junction temperature range of 0ºC to 125ºC are assured by design and characterization.
VBIAS is connected to VOUT when the V
VIN Quiescent Current
VBIAS Input Current
Buck Switch On Resistance
Fixed Off-Time Proportion
Feedback Voltage
Output Voltage Regulation
Feedback Input Bias Current
Soft Start Time
Buck Switch Current Limit
ENB Open Circuit Voltage
ENB Input Voltage Threshold
ENB Input Current
VIN Undervoltage Threshold
VIN Undervoltage Hysteresis
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Characteristics
3
OUT
V
T
Symbol
R
V
UVLO(hys)
JTSD(hys)
I
1,2
I
V
T
V
ENB(0)
I
target is between 3.3 and 5 V.
VIN(Q)
V
ENB(0)
DS(on)
V
BIAS
I
I
UVLO
JTSD
t
t
OUT
FB
CL
off
ss
OC
FB
at T
A
= 25°C, V
V
V
V
V
V
V
T
T
Based on calculated value
I
V
V
Output disabled
LOW level input (Logic 0), output enabled
V
V
V
Temperature increasing
Recovery = T
OUT
A
A
ENB
BIAS
ENB
BIAS
ENB
BIAS
FB
FB
ENB
IN
IN
= 25°C, I
= 125°C, I
rising
falling
> 0.4 V
< 0.4 V
= 0 mA to 3 A
= LOW, I
= LOW, I
= HIGH
= 0 V
= V
< 3 V
= V
IN
OUT
OUT
= 8 to 50 V (unless noted otherwise)
OUT
High Voltage Step Down Regulator
OUT
JTSD
Test Conditions
OUT
OUT
= 3 A
= 3 A
= 0 mA, V
= 0 mA, V
– T
JTSD(hys)
IN
IN
= 42 V,
= 42 V,
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
0.784
–400
Min.
–15
–10
3.5
0.5
2.0
0.7
6.6
–3
5
–
–
–
–
–
–
–
–
–
–100
Typ.
0.90
450
165
650
4.4
3.5
0.8
6.9
10
15
–
–
–
–
–
–
–
–
–
0.816
Max.
6.35
1.35
100
100
1.5
1.0
7.2
1.1
15
15
–1
5
–
3
5
7
–
–
–
Units
mΩ
mΩ
mA
mA
mA
ms
μA
nA
μA
°C
°C
%
%
V
A
A
V
V
V
V
4