Datasheet

LM2621
www.ti.com SNVS033C –MAY 2004–REVISED MARCH 2005
ELECTRICAL CHARACTERISTICS
Limits in standard typeface are for T
J
= 25°C, and limits in boldface type apply over the full operating temperature range of
−40°C to +85°C. Unless otherwise specified: V
DD
= V
OUT
= 3.3V.
Symbol Parameter Condition Typ Min Max Units
V
IN_ST
Minimum Start-Up Supply Voltage
(1)
I
LOAD
= 0mA 1.1 1.2 V
V
IN_OP
Minimum Operating Supply Voltage I
LOAD
= 0mA 0.65 V
(once started)
V
FB
FB Pin Voltage 1.24 1.2028 1.2772 V
V
OUT_M
Maximum Output Voltage 14 V
AX
V
HYST
Hysteresis Voltage
(2)
30 45 mV
η Efficiency V
IN
= 3.6V; V
OUT
= 5V; I
LOAD
= 500mA 87
%
V
IN
= 2.5V; V
OUT
= 3.3V; I
LOAD
= 200mA 87
D Switch Duty Cycle 70 60 80 %
I
DD
Operating Quiescent Current
(3)
FB Pin > 1.3V; EN Pin at V
DD
80 110 µA
I
SD
Shutdown Quiescent Current
(2)
V
DD
, BOOT and SW Pins at 5.0V; 0.01 2.5 µA
EN Pin <200mV
I
CL
Switch Peak Current Limit 2.85 A
R
DS_ON
MOSFET Switch On Resistance 0.17 Ω
Enable Section
V
EN_LO
EN Pin Voltage Low
(4)
0.15V
DD
V
V
EN_HI
EN Pin Voltage High
(4)
0.7V
DD
V
(1) Output in regulation, V
OUT
= V
OUT (NOMINAL
) ± 5%
(2) This is the total current into pins V
DD
, BOOT, SW and FREQ.
(3) This is the current into the V
DD
pin.
(4) When the EN pin is below V
EN_LO
, the regulator is shut down; when it is above V
EN_HI
, the regulator is operating.
PIN DESCRIPTION
Pin Name Function
1 PGND Power Ground
2 EN Active-Low Shutdown Input
3 FREQ Frequency Adjust. An external resistor connected between this pin and Pin 6 (V
DD
) sets the switching
frequency of the LM2621.
4 FB Output Voltage Feedback
5 SGND Signal Ground
6 V
DD
Power Supply for Internal Circuitry
7 BOOT Bootstrap Supply for the Gate Drive of Internal MOSFET Power Switch
8 SW Drain of the Internal MOSFET Power Switch
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