RT7257J
Absolute Maximum Ratings (Note 1)
z Supply Input Voltage, VIN ----------------------------------------------------------------------------------------- −0.3V to 20V
z Switch Voltage, SW ------------------------------------------------------------------------------------------------ −0.3V to (VIN + 0.3V)
z VBOOT − VSW ---------------------------------------------------------------------------------------------------------- −0.3V to 6V
z Other Pins Voltage ------------------------------------------------------------------------------------------------- −0.3V to 20V
z Power Dissipation, PD @ TA = 25°C
SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------- 1.333W
z Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad), θJA ---------------------------------------------------------------------------------------- 75°C/W
SOP-8 (Exposed Pad), θJC --------------------------------------------------------------------------------------- 15°C/W
z Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------- 260°C
z Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
z Storage Temperature Range -------------------------------------------------------------------------------------- −65°C to 150°C
z ESD Susceptibility (Note 3)
HBM (Human Body Model)---------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions (Note 4)
z Supply Input Voltage, VIN ----------------------------------------------------------------------------------------- 4.5V to 18V
z Junction Temperature Range-------------------------------------------------------------------------------------- −40°C to 125°C
z Ambient Temperature Range-------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 12V, TA = 25°C, unless otherwise specified)
Parameter
Shutdown Supply Current
Supply Current
Symbol
Test Conditions
Min
--
Typ
0.5
0.8
0.8
Max
3
Unit
μA
mA
V
VEN = 0V
VEN = 3 V, VFB = 0.9V
--
1.2
Reference Voltage
VREF
GEA
4.5V ≤ VIN ≤ 18V
0.788
0.812
Error Amplifier
ΔIC = ±10μA
--
--
--
940
110
90
--
--
--
μA/V
mΩ
Transconductance
High Side Switch
On-Resistance
Low Side Switch
On-Resistance
High Side Switch Leakage
Current
RDS(ON)1
RDS(ON)2
mΩ
VEN = 0V, VSW = 0V
--
--
0
10
--
μA
A
Upper Switch Current Limit
Min. Duty Cycle, VBOOT − VSW = 4.8V
5.1
4.7
340
100
COMP to Current Sense
Transconductance
GCS
--
--
A/V
kHz
kHz
Oscillation Frequency
fOSC1
fOSC2
300
--
380
--
Short Circuit Oscillation
Frequency
VFB = 0V
Maximum Duty Cycle
Minimum On Time
DMAX
tON
VFB = 0.7V
--
--
93
--
--
%
100
ns
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is a registered trademark of Richtek Technology Corporation.
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4
DS7257J-02 September 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
