LTC3772B Datasheet, PDF (3/20 Pages) Linear Technology – Micropower No RSENSE Constant Frequency Step-Down DC/DC Controller

LTC3772B
ELECTRICAL CHARACTERISTICS The ● indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 4.2V unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX
V_FB Input Current
(Note 5)
–10
2
10
Overvoltage Protect Threshold
Overvoltage Protect Hysteresis
Measured at V_FB
0.850
0.880
40
0.910
Oscillator Frequency
Normal Operation
Output Short Circuit
V_FB = 0.8V
V_FB = 0V
500
550
650
200
Gate Drive Rise Time
C_LOAD = 3000pF
40
Gate Drive Fall Time
Peak Current Sense Voltage
C_LOAD = 3000pF
I_PRG = GND (Note 6)
I_PRG = Floating
I_PRG = V_IN
40
● 55
70
85
● 120
138
155
● 190
208
225
Default Soft-Start Time
Time for V_FB to Ramp from 0.05V to 0.75V
0.8
UNITS
nA
V
mV
kHz
kHz
ns
ns
mV
mV
mV
ms
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3772BETS8/LTC3772BEDDB are guaranteed to meet
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formula:
T_J = T_A + (P_D • θ_JA°C/W)
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5: The LTC3772B is tested in a feedback loop that servos V_FB to the
output of the error amplifier while maintaining I_TH/RUN at the midpoint of
the current limit range.
Note 6: Peak current sense voltage is reduced dependent on duty cycle as
given in Figure 1.
TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current (No Load)
vs Input Voltage
225
220
215
210
205
200
195
2 3 4 5 6 7 8 9 10
V_IN (V)
3772B G01
Quiescent Current (No Load)
vs Temperature
250
V_IN = 5V
230
210
190
170
150
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80 100
3772B G02
Quiescent Current (Shutdown)
vs Input Voltage
25
20
15
10
5
0
2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
3772B G03
3772bfa
3