LM3687 Datasheet, PDF (8/35 Pages) National Semiconductor (TI) – Step-Down DC-DC Converter with Integrated Low Dropout Regulator and Startup Mode

LM3687
SNVS473A – DECEMBER 2007 – REVISED JULY 2008
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Electrical Characteristics^{(1) (2)} Linear Regulator, Normal Mode
Symbol
Parameter
Condition
Typ
ΔV_{OUT_LIN} /
V_{OUT_LIN(NOM)}
Output Voltage
Accuracy
In startup and normal mode
ΔV_{OUT_LIN} /
V_{IN_LIN} = V_{OUT_LIN(NOM)} + 0.3V to
0.3
ΔV_{IN_LIN}
Line Regulation Error
4.5V, V_BATT = 4.5V
ΔV_{OUT_LIN} /
V_BATT = V_{OUT_LIN(NOM)} + 1.5V (≥2.7V)
0.5
ΔV_BATT
to 5.5V
ΔV_{OUT_LIN} / ΔmA Load Regulation Error I_{OUT_LIN} = 1mA to 350mA
10
V_{DO_VIN_LIN}
I_{OUT_LIN} = 350mA ,
Output Voltage Dropout ^VBATT ^{= V}OUT_LIN(NOM) ^{+ 1.5V (≥2.7V)}
85
(3)
I_{OUT_LIN} = 150mA ,
V_BATT = V_{OUT_LIN(NOM)} + 1.3V (≥2.7V)
42
I_{Q_VIN_LIN}
Quiescent Current into I_{OUT_LIN} = 0mA
10
V_{IN_LIN}
Shutdown Current into V_{EN_LIN} = 0V
0.1
V_{IN_LIN}
I_{SC_LIN}
Output Current
V_{OUT_LIN} = 0V
500
(short circuit)
PSRR
Sine modulated V_BATT,
f = 10Hz
70
f = 100Hz
65
f = 1kHz
45
Power Supply
Rejection Ratio
Sine modulated V_IN
f = 10Hz
80
f = 100Hz
90
f = 1kHz
95
f = 10kHz
85
E_N
Output Noise linear
10Hz - 100kHz
100
regulator
ΔV_{OUT_LIN}
Dynamic line transient
response V_{IN_LIN}
V_{IN_LIN} = V_{OUT_LIN(NOM)} + 0.3V to
V_{OUT_LIN(NOM)} + 0.9V
tr, tf = 10µs
±1
Dynamic line transient
response V_BATT
V_BATT = V_{OUT_LIN(NOM)} + 1.5V to
V_{OUT_LIN(NOM)} + 2.1V
tr, tf = 10µs
±15
ΔV_{OUT_LIN}
Dynamic load transient Pulsed load 0 ... 350mA
±30
response
di/dt = 350mA/1µs
Limit
Min
Max
-1.5
1.5
-2.0
2.0
1
3.1
60
200
100
28
1
350
Units
%
%
mV/V
µV/mA
mV
mV
µA
µA
mA
dB
dB
µV_RMS
mVp
mVp
mVp
(1) All voltages are with respect to the potential at the SGND pin.
(2) Min and Max limits are guaranteed by design, test, or statistical analysis. Typical numbers are not guaranteed, but do represent the
most likely norm. Unless otherwise specified, conditions for typ. specifications are: V_BATT = 3.6V and T_A = 25°C.
(3) This specification does not apply if the battery voltage V_BATT needs to be decreased below the minimum operating limit of 2.7V.
8
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