LTC3727-1_15 Datasheet, PDF (3/32 Pages) Linear Technology – High Efficiency, 2-Phase Synchronous Step-Down Switching Regulators

LTC3727/LTC3727-1
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 15V, V_{RUN/SS1, 2} = 5V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V_LOADREG
g_{m1, 2}
g_{mGBW1, 2}
I_Q
V_FCB
I_FCB
V_BINHIBIT
Output Voltage Load Regulation
Transconductance Amplifier g_m
Transconductance Amplifier GBW
Input DC Supply Current
Normal Mode
Shutdown
Forced Continuous Threshold
Forced Continuous Pin Current
Burst Inhibit (Constant Frequency)
Threshold
(Note 4)
Measured in Servo Loop; ΔI_TH Voltage = 1.2V to 0.7V ●
Measured in Servo Loop; ΔI_TH Voltage = 1.2V to 2.0V ●
I_{TH1, 2} = 1.2V; Sink/Source 5μA (Note 4)
I_{TH1, 2} = 1.2V (Note 4)
(Note 5)
V_IN = 15V, EXTV_CC Tied to V_OUT1, V_OUT1 = 8.5V
V_{RUN/SS1, 2} = 0V
● 0.76
V_FCB = 0.85V
– 0.30
Measured at FCB pin
0.1
– 0.1
1.3
3
670
20
0.800
– 0.18
6.8
0.5
%
– 0.5
%
mmho
MHz
μA
35
μA
0.84
V
– 0.05
μA
7.3
V
UVLO
V_OVL
I_SENSE
Undervoltage Lockout
Feedback Overvoltage Lockout
Sense Pins Total Source Current
V_IN Ramping Down
●
3.5
4
V
Measured at V_{OSENSE1, 2}
● 0.84 0.86 0.88
V
(Each Channel) V_SENSE1–_{, 2} – = V_SENSE1+_{, 2}+ = 0V
– 85 – 60
μA
DF_MAX
Maximum Duty Factor
In Dropout
98
99.4
%
I_{RUN/SS1, 2}
Soft-Start Charge Current
V_{RUN/SS1, 2} = 1.9V
0.5
1.2
μA
V_{RUN/SS1, 2} ON RUN/SS Pin ON Threshold
V_RUN/SS1, V_RUN/SS2 Rising
1.0
1.5
1.9
V
V_{RUN/SS1, 2} LT RUN/SS Pin Latchoff Arming Threshold V_RUN/SS1, V_RUN/SS2 Rising from 3V (LTC3727 Only)
4.1
4.5
V
I_{SCL1, 2}
RUN/SS Discharge Current
Soft-Short Condition V_{OSENSE1, 2} = 0.5V,
V_{RUN/SS1, 2} = 4.5V (LTC 3727 Only)
0.5
2
4
μA
I_SDLHO
Shutdown Latch Disable Current
V_{OSENSE1, 2} = 0.5V (LTC3727 Only)
1.6
5
μA
V_SENSE(MAX) Maximum Current Sense Threshold
V_{OSENSE1, 2} = 0.7V,V_SENSE1–_{, 2}– = 12V
● 105
135
165
mV
TG1, 2 t_r
TG1, 2 t_f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C_LOAD = 3300pF
C_LOAD = 3300pF
50
90
ns
50
90
ns
BG Transition Time:
(Note 6)
BG1, 2 t_r
BG1, 2 t_f
Rise Time
Fall Time
C_LOAD = 3300pF
C_LOAD = 3300pF
40
90
ns
40
80
ns
TG/BG t_1D
Top Gate Off to Bottom Gate On Delay C_LOAD = 3300pF Each Driver
Synchronous Switch-On Delay Time
90
ns
BG/TG t_2D
Bottom Gate Off to Top Gate On Delay C_LOAD = 3300pF Each Driver
Top Switch-On Delay Time
90
ns
t_ON(MIN)
Minimum On-Time
INTV_CC Linear Regulator
V_INTVCC
Internal V_CC Voltage
V_LDO INT
INTV_CC Load Regulation
V_LDO EXT
EXTV_CC Voltage Drop
V_EXTVCC
EXTV_CC Switchover Voltage
V_LDOHYS
EXTV_CC Hysteresis
Oscillator and Phase-Locked Loop
Tested with a Square Wave (Note 7)
8.5V < V_IN < 30V, V_EXTVCC = 6V
I_CC = 0mA to 20mA, V_EXTVCC = 6V
I_CC = 20mA, V_EXTVCC = 8.5V
I_CC = 20mA, EXTV_CC Ramping Positive
180
ns
7.2
7.5
7.8
V
0.2
1.0
%
70
160
mV
● 6.9
7.3
V
0.3
V
f_NOM
Nominal Frequency
f_LOW
Lowest Frequency
f_HIGH
Highest Frequency
V_PLLFLTR = 1.2V
V_PLLFLTR = 0V
V_PLLFLTR ≥ 2.4V
350 380 430
kHz
220 255 290
kHz
460 530 580
kHz
3727fc
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