LTC3448_15 Datasheet, PDF (3/20 Pages) Linear Technology – 1.5MHz/2.25MHz, 600mA Synchronous Step-Down Regulator with LDO Mode

LTC3448
ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T_A = 25°C. V_IN = 3.6V unless otherwise specified.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
I_S
Input DC Bias Current
V_IN = 3.6V (Note 5)
Active Mode (Pulse Skip, No LRO)
V_FB = 0.5V or V_OUT = 90%, I_LOAD = 0A, 1.5MHz
V_FB = 0.5V or V_OUT = 90%, I_LOAD = 0A, 2.25MHz
250 375
275 400
Linear Regulator Operation (LRO)
I_LOAD ≤ I_LDO(ON)
32
43
Shutdown
V_RUN = 0V, V_IN = 5.5V
0.1
1
f_OSC
Oscillator Frequency
FREQ = Low, V_IN = 3.6V
FREQ = High
● 1.2
1.5
1.8
● 1.8
2.25
2.7
f_SYNC
V_TH(SYNC)
R_PFET
R_NFET
I_LSW
V_RUNH
V_RUNL
I_RUN
V_FREQH
V_FREQL
I_FREQ
V_MODEH
V_MODEL
I_MODE
I_SYNC
I_LDO(ON)
I_LDO(OFF)
Synchronization Frequency
SYNC Activation Input Threshold
R_DS(ON) of P-Channel FET
R_DS(ON) of N-Channel FET
SW Leakage
RUN Threshold High
RUN Threshold Low
RUN Leakage Current
FREQ Threshold High
FREQ Threshold Low
FREQ Leakage Current
MODE Threshold High
MODE Threshold Low
MODE Leakage Current
SYNC Leakage Current
LRO ON Load Current Threshold
LRO OFF Load Current Threhold
(Note 6)
I_SW = 100mA
I_SW = –150mA
V_RUN = 0V, V_SW = 0V or 5V, V_IN = 5V
2.2mH Inductor (Note 8)
1.5
>4
1
1.3
0.4
0.35
±0.01 ±1
● 1.5
●
0.3
●
±0.01 ±1
● V_IN – 1
●
1
●
±0.01 ±1
● V_IN – 0.15
●
0.12
●
±0.1
±1
●
±0.01 ±1
3
5
8
11
17
UNITS
µA
µA
µA
µA
MHz
MHz
MHz
V
Ω
Ω
µA
V
V
µA
V
V
µA
V
V
µA
µA
mA
mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3448E is guaranteed to meet performance 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)(43°C/W)
Note 4: The LTC3448 is tested in a proprietary test mode that connects
V_FB to the output of the error amplifier.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. LRO is “linear regulator operation.”
Note 6: 4MHz operation is guaranteed by design but is not production
tested and is subject to duty cycle limitations.
Note 7: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature is active. Continu-
ous operation above the specified maximum operating junction tempera-
ture may impair device reliability.
Note 8: The load current below which the switching regulator turns off and
the LDO turns on is, to first order, inversely proportional to the value of
the inductor. This effect is covered in more detail in the Operation section.
This parameter is not production tested but is guaranteed by design.
Note 9: For 2.5V < V_IN < 2.7V the output voltage is limited to V_IN – 0.7V
to ensure regulation in linear regulator mode. This parameter is not
production tested but is guaranteed by design.
3448f
3