Datasheet

1
1e1 1e2 1e3 1e4
OUTPUT CURRENT (mA)
0.00
20.00
40.00
60.00
80.00
100.00
EFFICIENCY (%)
V
IN
= 3.5V
V
IN
= 3V
1
1e1 1e2 1e3 1e4
OUTPUT CURRENT (mA)
0.00
18.00
36.00
54.00
72.00
90.00
EFFICIENCY (%)
V
IN
= 4.5V
V
IN
= 4V
LP3972
www.ti.com SNVS468K –SEPTEMBER 2006–REVISED MAY 2013
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)(4)
Symbol Parameter Test Conditions Min Typ Max Unit
V
OUT
Output Voltage Accuracy Default V
OUT
−3 +3 %
Eff Efficiency Load Current = 500 mA 95 %
I
SHDN
Shutdown Supply Current EN is de-asserted 0.1 µA
Sync Mode Clock Frequency Synchronized from 13 MHz System Clock 10.4 13 15.6 MHz
f
OSC
Internal Oscillator Frequency 2.0 MHz
I
PEAK
Peak Switching Current Limit 2.1 2.4 A
I
Q
Quiescent Current "On" No Load PFM Mode 21
µA
No Load PWM Mode 200
R
DSON
(P) Pin-Pin Resistance PFET 240 mΩ
R
DSON
(N) Pin-Pin Resistance NFET 200 mΩ
T
ON
Turn On Time Start up from Shut-down 500 µsec
C
IN
Input Capacitor Capacitance for Stability 8 µF
C
O
Output Capacitor Capacitance for Stability 8 µF
(1) All voltages are with respect to the potential at the GND pin.
(2) All limits specified at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are
production tested, ensured through statistical analysis or ensured by design. All limits at temperature extremes are ensured 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.
Buck1 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 V
IN
= 4.0-4.5 volts V
OUT
= 1.4 volts Forced PWM
Figure 8. Figure 9.
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