LP3971 Datasheet, PDF (13/57 Pages) National Semiconductor (TI) – POWER MANAGEMENT UNIT FOR ADVANCED APPLICATION PROCESSORS

LP3971
www.ti.com
SNVS432U – JANUARY 2006 – REVISED OCTOBER 2008
Buck Converters SW1, SW2, SW3
Unless otherwise noted, V_IN = 3.6V, C_IN = 10 μF, C_OUT = 10 μF, L_OUT = 2.2 μH ceramic. Typical values and limits appearing in
normal type apply for T_J = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for
operation, −40°C to +125°C. ^{(1) (2) (3)} and ⁽⁴⁾.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V_OUT
Eff
Output Voltage Accuracy
Efficiency
Default V_OUT
Load Current = 500 mA
−3
+3
%
95
%
I_SHDN
Shutdown Supply Current
EN is de-asserted
0.1
μA
Sync Mode Clock Frequency
Synchronized from 13 MHz System 10.4
13
15.6
MHz
Clock
f_OSC
I_PEAK
I_Q
Internal Oscillator Frequency
Peak Switching Current Limit
Quiescent Current “On”
No Load PFM Mode
No Load PWM Mode
2.0
MHz
2.1
2.4
A
21
μA
200
R_DSON (P)
R_DSON (N)
T_ON
C_IN
C_O
Pin-Pin Resistance PFET
Pin-Pin Resistance NFET
Turn On Time
Input Capacitor
Output Capacitor
Start up from Shut-down
Capacitance for Stability
Capacitance for Stability
240
200
500
8
8
mΩ
mΩ
μsec
µF
µF
(1) All voltages are with respect to the potential at the GND pin.
(2) All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits
are production tested, guaranteed through statistical analysis or guaranteed by design. All limits at temperature extremes are
guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing
Quality Level (AOQL).
(3) The input voltage range recommended for ideal applications performance for the specified output voltages is given below:V_IN = 2.7V to
5.5V for 0.80V < V_OUT < 1.8VV_IN = (V_OUT+ 1V) to 5.5V for 1.8V ≤ V_OUT ≤ 3.3V
(4) Test condition: for V_OUT less than 2.7V, V_IN = 3.6V; for V_OUT greater than or equal to 2.7V, V_IN = V_OUT+ 1V.
Buck 1 Output Efficiency vs. Load Current Varied from 1mA to 1.5 Amps
V_IN = 3, 3.5 volts V_OUT = 1.4 volts Forced PWM
100.00
V_IN = 3V
80.00
60.00
V_IN = 3.5V
V_IN = 4.0, 4.5 volts V_OUT = 1.4 volts Forced PWM
90.00
72.00 ^{VIN = 4V}
54.00
V_IN = 4.5V
40.00
36.00
20.00
18.00
0.00
1
1e1
1e2
1e3
1e4
OUTPUT CURRENT (mA)
0.00
1
1e1
1e2
1e3
1e4
OUTPUT CURRENT (mA)
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