SC1470 Datasheet, PDF (4/25 Pages) Semtech Corporation – Synchronous Buck Pseudo Fixed Frequency Power Supply Controller

SC1470
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Test Conditions: V_BAT = 15V, EN/PSV = 5V, VCCA = VDDP = 5V, V_OUT = 1.25V, R_TON = 1MΩ
Parameter
Conditions
25°C
-40°C to 125°C Units
PGD Fault Delay
FB forced outside PGD window.
VCCA Undervoltage Threshold Falling (100mV Hysteresis)
Over Temperature Lockout
10°C Hysteresis
Inputs/Outputs
Logic Input Low Voltage
EN/PSV low
Logic Input High Voltage
EN High, PSV low (Floating)
Logic Input High Voltage
EN/PSV high
EN/PSV Input Resistance
R Pullup to VCCA
R Pulldown to VSSA
Soft Start
Soft-Start Ramp Time
EN/PSV high to PGD high
Under-Voltage Blank Time
EN/PSV high to UV high
Gate Drivers
Shoot-Through Delay ⁽⁴⁾
DH or DL rising
DL Pull-Down Resistance
DL low
DL Pull-Up Resistance
DL high
DH Pull-Down Resistance
DH low, BST - LX = 5V
DH Pull-Up Resistance ⁽⁵⁾
DH high, BST - LX = 5V
DL Sink Current
DL = 2.5V
DL Source Current
DL = 2.5V
DH Sink/Source Current
DH = 2.5V
Min Typ Max Min Max
5
µs
4.0
3.7
4.3
V
165
°C
1.2
V
2.0
V
3.1
V
1.5
MΩ
1.0
MΩ
440
clks⁽³⁾
440
clks⁽³⁾
30
ns
0.8
1.6
Ω
2
4
Ω
2
4
Ω
2
4
Ω
3.1
A
1.3
A
1.3
A
Notes:
(1) When the inductor is in continuous and discontinuous conduction mode, the output voltage will have a DC
regulation level higher than the error-comparator threshold by 50% of the ripple voltage.
(2) Using a current sense resistor, this measurement relates to PGND minus the voltage of the source on the low-
side MOSFET. These values guaranteed by the ILIM Source Current and Current Comparator Offset tests.
(3) clks = switching cycles.
(4) Guaranteed by design. See Shoot-Through Delay Timing Diagram.
(5) Semtech’s SmartDriver^TM FET drive first pulls DH high with a pullup resistance of 10Ω (typ.) until LX = 1.5V (typ.).
At this point, an additional pullup device is activated, reducing the resistance to 2Ω (typ.). This negates the need for
an external gate or boost resistor.
 2005 Semtech Corp.
4
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