A4491 Datasheet, PDF (5/16 Pages) Allegro MicroSystems – Designed to provide the power supply requirements of printers, office automation, industrial, and portable equipment, the A4491 provides three high current,

A4491
Triple Output Step-Down Switching Regulator
ELECTRICAL CHARACTERISTICS^* at T_A = 25°C, V_BB = 12 V, V_DD supplied externally, unless noted otherwise
Characteristics
Symbol
Test Conditions
Min. Typ.
General
VBB Quiescent Current
VDD Supply Range
VDD Quiescent Current
I_BBON
I_BBOFF
V_DD
I_DD
ENBx = high, I_LOAD = 0 mA, V_BB = 12 V,
current drawn by feedback resistors ignored
ENBx = 0 V
ENBx = high
ENBx = 0 V
–
1
–
1
3.3
–
–
–
–
1
REG1, REG2, and REG3
Feedback Input Bias Current
Feedback Voltage
Fixed Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Buck Switch On-Resistance
Current Limit Threshold
Soft Start Duration
Logic Inputs and Outputs
I_BIAS
V_FB
f_SW
DC_max
DC_min
R_DS(on)
I_LIM
t_ss
With respect to 0.8 V target voltage; V_BB = 6 to 23 V
T_J = 25°C, I_LOAD = 1.5 A, V_BB = 6.0 V
T_J = 125°C, I_LOAD = 1.5 A, V_BB = 6.0 V
T_J = 25°C, I_LOAD = 1.5 A, V_BB = 4.5 V
T_J = 125°C, I_LOAD = 1.5 A, V_BB = 4.5 V
Peak current through switch with D = 0.9
–400
–
470
90
–
–
–
–
–
2.0
0.625
–100
±1
550
–
5
450
700
560
870
1.25
ENBx Input Voltage
ENBx Input Hysteresis
ENBx Input Current
PORZ Output (Open Drain)
PORZ Output Leakage Current
Power-On Reset Duration
Protection
V_IL
V_IH
V_I(hys)
I_IL
V_PORZL
I_PORZH
t_POR
V_IH ≤ 5 V
I_PORZL = 1 mA, fault asserted
V_PORZ = 5 V, fault not asserted
C_POR = 470 nF
–
–
2.0
–
300
500
–1
–
–
–
–1
–
75
115
VREGx Undervoltage Lockout Startup
VREGx Undervoltage Lockout Shutdown
VREGx Undervoltage Lockout
Startup Hysteresis
V_REGUV(su)
V_REGUV(sd)
FB1, FB2, and FB3 rising
FB1, FB2, and FB3 falling
V_REGUV(suhys)
–
85
–
80
–
5
VBB Undervoltage Lockout Startup
V_BBUV(su)
V_BBCPUV(su)
No external VDD supply, V_BB rising
External VDD supply, V_BB rising
3.7
4.3
3.8
4.2
VBB Undervoltage Lockout Shutdown
V_BBUV(sd)
V_BBCPUV(sd)
No external VDD supply, V_BB falling
External VDD supply, V_BB falling
3.6
4.1
3.0
3.5
VBB Undervoltage Lockout
Shutdown Hysteresis
V_BBUV(sdhys) No external VDD supply
V_{BBCPUV(sdhys)} External VDD supply
–
500
–
600
VBB Undervoltage Warning Threshold
V_BBUV(por)
V_BB falling (forces PORZ low); switchers continue
to operate
–
3.6
Junction Overtemperature Shutdown
Junction Overtemperature Shutdown
Hysteresis
T_JTSD
T_JTSD(hys)
Temperature rising
Recovery = T_JTSD –T_JTSD(hys)
–
165
–
15
*_{For input and output current specifications, negative current is defined as coming out of (sourcing) the specified pin.}
Max.
2
–
5.5
6
–
100
–
630
–
–
–
–
–
–
1.875
0.8
–
–
1
0.4
1
155
–
–
–
4.7
4.6
4.7
4.3
–
–
–
–
–
Units
mA
μA
V
mA
μA
nA
%
kHz
%
%
mΩ
mΩ
mΩ
mΩ
A
ms
V
V
mV
μA
V
μA
ms
%V_FB
%V_FB
%
V
V
V
V
mV
mV
V
°C
°C
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com