Datasheet

LM3242
SNOSB48D –OCTOBER 2011–REVISED MARCH 2013 www.ti.com
Electrical Characteristics
Limits in standard typeface are for T
A
= T
J
= 25°C. Limits in boldface type apply over the full operating ambient temperature
range (−30°C ≤ T
A
= T
J
≤ +90°C). Unless otherwise noted, all specifications apply to the Typical Application Circuit (page 1)
with VIN = EN = 3.6V, and BPEN = NC = 0V.
Symbol Parameter Condition Min Typ Max Units
V
FB,MIN
Feedback voltage at PWM mode, VCON = 0.16V
(1)
0.38 0.4 0.42 V
minimum setting
V
FB,MAX
Feedback voltage at PWM mode, VCON = 1.44V, V
IN
= 4.0V 3.55 3.6 3.65 V
maximum setting
I
SHDN
Shutdown supply current EN = SW = VCON = FB = BPEN = NC = 0.1 1.0 µA
0V
(2)
I
Q
_PWM PWM mode quiescent PWM mode, No switching 650 795 µA
current VCON = 0.13V, FB = 1V
(3)
EN = VIN, BPEN = NC = 0V, SW = µA
I
Q
_SLEEP Low-power SLEEP mode TriState 60 80
VCON < 0.08V
(4)
I
Q
_ECO ECO mode Quiescent ECO mode, No switching 60 80 µA
current VCON = 0.8V, FB = 2.05V
(3)
R
DSON (P)
Pin-pin resistance for PFET V
IN
= V
GS
= 3.6V, I
SW
= 200 mA 170 260 mΩ
R
DSON (N)
Pin-pin resistance for NFET VIN = V
GS
= 3.6V, I
SW
= −200 mA 110 200 mΩ
Pin-Pin resistance for
R
DSON (BP)
V
IN
= V
GS
= 3.1V, I
SW
= −200 mA 80 110 mΩ
BPFET
I
LIM P
PFET switch peak current
(5)
1300 1450 1600 mA
limit
BPFET switch peak current
I
LIM BP
V
FB
= V
IN
− 1V
(5)
310 400 mA
limit
F
OSC
Internal oscillator frequency 5.7 6 6.3 MHz
V
IH
EN, BPEN Logic high input 1.2 V
threshold
V
IL
EN, BPEN Logic low input 0.4 V
threshold
Gain VCON to V
OUT
gain 0.16V ≤ VCON ≤ 1.44V
(6)
2.5 V/V
I
VCON
VCON pin leakage current VCON = 1.0V ±1 µA
Auto Bypass Detection VCON = 1.2V (V
OUT-SET
= 3.0V)
V
BP,NEG
165 200 235 mV
Negative Threshold V
IN
= 3.2V, R
L
= 6Ω (I
OUT
= 500 mA)
(7)
Auto Bypass Detection VCON = 1.2V (V
OUT-SET
= 3.0V)
V
BP,POS
215 250 285
Positive Threshold V
IN
= 3.25V, R
L
= 6Ω (I
OUT
= 500 mA)
(8)
Auto Bypass I
OUT
Slew
I
BP,SLEW
BPEN = High, Forced Bypass 1600 mA
Current
(1) All 0.4V V
OUT
specifications are at steady-state only.
(2) Shutdown current includes leakage current of PFET.
(3) I
q
specified here is when the part is not switching under test mode conditions. For operating quiescent current at no load, refer to
datasheet curves.
(4) FB has 200 kΩ to SGND.
(5) Current limit is built-in, fixed, and not adjustable.
(6) Care should be taken to keep the VCON pin voltage less than the VIN pin voltage as this can place the part into a manufacturing test
mode.
(7) Entering Bypass Mode V
IN
is compared to the programmed output voltage (2.5 × VCON). When V
IN
− (2.5 × VCON) falls below V
BP,NEG
longer than T
BP,NEG
, the Bypass FET turns on, and the switching FET turns on.
(8) Bypass Mode is exited when V
IN
− (2.5 × VCON) exceeds V
BP,POS
longer than T
BP,POS
, and PWM mode resumes. The hysteresis for
the bypass detection threshold V
BP,POS
-V
BP,NEG
will always be positive and will be approximately 50 mV.
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