LTC1438 Datasheet, PDF (6/32 Pages) Linear Technology – Dual High Efficiency, Low Noise, Synchronous Step-Down Switching Regulators

LTC1438/LTC1439
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Oscillator Frequency
vs Temperature
10
5
f_O
–5
–10
– 40 –15
10 35 60 85
TEMPERATURE (°C)
110 135
1438 G10
Maximum Current Sense
Threshold Voltage vs Temperature
154
RUN/SS Pin Current
vs Temperature
4
3
2
1
0
– 40 –15
10 35 60 85
TEMPERATURE (°C)
110 135
1438 G11
SFB1 Pin Current vs Temperature
0
– 0.25
–1.50
– 0.75
–1.00
–1.25
–1.50
– 40 –15
10 35 60 85
TEMPERATURE (°C)
110 135
1438 G12
Transient Response
Transient Response
152
V_OUT
50mV/DIV
150
V_OUT
50mV/DIV
148
146
– 40 –15
10 35 60 85
TEMPERATURE (°C)
110 135
1438 G13
Burst Mode Operation
I_LOAD = 50mA to 1A
1438 G14
Soft Start: Load Current vs Time
V_OUT
20mV/DIV
V_ITH
200mV/DIV
I_LOAD = 50mA
RUN/SS
5V/DIV
INDUCTOR
CURRENT
1A/DIV
1438 G16
1438 G17
I_LOAD = 1A to 3A
1438 G15
Auxiliary Regulator Load
Regulation
12.2
EXTERNAL PNP: 2N2907A
12.1
12.0
11.9
11.8
11.7
0
40
80 120 160 200
AUXILIARY LOAD CURRENT (mA)
1438 G18
6