LTC3729_15 Datasheet, PDF (3/30 Pages) Linear Technology – 550kHz, PolyPhase, High Efficiency, Synchronous Step-Down Switching Regulator

LTC3729
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 15V, V_RUN/SS = 5V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loop
V_EAIN
V_SENSEMAX
Regulated Feedback Voltage
Maximum Current Sense Threshold
(Note 3); I_TH Voltage = 1.2V
V_SENSE– = 5V
V_{SENSE1, 2} = 5V
l 0.792
l 62
65
I_INEAIN
Feedback Current
(Note 3)
V_LOADREG Output Voltage Load Regulation
(Note 3)
Measured in Servo Loop; I_TH Voltage = 0.7V
l
Measured in Servo Loop; I_TH Voltage = 2V
l
V_REFLNREG Reference Voltage Line Regulation V_IN = 3.6V to 30V (Note 3)
V_OVL
Output Overvoltage Threshold
Measured at V_EAIN
l 0.84
UVLO
Undervoltage Lockout
V_IN Ramping Down
3
g_m
Transconductance Amplifier g_m
I_TH = 1.2V; Sink/Source 5µA; (Note 3)
g_mOL
Transconductance Amplifier Gain
I_TH = 1.2V; (g_mxZ_L; No Ext Load); (Note 3)
I_Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 4)
EXTV_CC Tied to V_OUT ; V_OUT = 5V
V_RUN/SS = 0V
I_RUN/SS
Soft-Start Charge Current
V_RUN/SS = 1.9V
–0.5
V_RUN/SS
RUN/SS Pin ON Threshold
V_RUN/SS Rising
1.0
V_RUN/SSLO RUN/SS Pin Latchoff Arming
V_RUN/SS Rising from 3V
I_SCL
RUN/SS Discharge Current
Soft Short Condition V_EAIN = 0.5V; V_RUN/SS = 4.5V
0.5
I_SDLDO
Shutdown Latch Disable Current
V_EAIN = 0.5V
I_SENSE
Total Sense Pins Source Current
Each Channel; V_{SENSE1–, 2–} = V_{SENSE1+, 2+} = 0V
–85
DF_MAX
Maximum Duty Factor
In Dropout
98
TG1, 2 t_r
TG1, 2 t_f
Top Gate Transition Time:
Rise Time
Fall Time
C_LOAD = 3300pF
C_LOAD = 3300pF
BG1, 2 t_r
BG1, 2 t_f
Bottom Gate Transition Time:
Rise Time
Fall Time
C_LOAD = 3300pF
C_LOAD = 3300pF
TG/BG t_1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time C_LOAD = 3300pF Each Driver
BG/TG t_2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C_LOAD = 3300pF Each Driver
t_ON(MIN)
Minimum On-Time
Tested with a Square Wave (Note 5)
Internal V_CC Regulator
V_INTVCC
Internal V_CC Voltage
6V < V_IN < 30V; V_EXTVCC = 4V
4.8
V_LDO INT
INTV_CC Load Regulation
I_CC = 0 to 20mA; V_EXTVCC = 4V
V_LDO EXT EXTV_CC Voltage Drop
I_CC = 20mA; V_EXTVCC = 5V
V_EXTVCC
EXTV_CC Switchover Voltage
I_CC = 20mA, EXTV_CC Ramping Positive
l 4.5
V_LDOHYS
EXTV_CC Switchover Hysteresis
I_CC = 20mA, EXTV_CC Ramping Negative
Oscillator and Phase-Locked Loop
0.800
75
75
–5
0.1
–0.1
0.002
0.86
3.5
3
1.5
580
20
–1.2
1.5
3.8
2
1.6
–60
99.5
30
40
30
20
90
90
100
5.0
0.2
80
4.7
0.2
0.808
88
85
–50
0.5
–0.5
0.02
0.88
4
40
1.9
4.5
4
5
90
90
90
90
5.2
1.0
160
V
mV
mV
nA
%
%
%/V
V
V
mmho
V/mV
µA
µA
µA
V
V
µA
µA
µA
%
ns
ns
ns
ns
ns
ns
ns
V
%
mV
V
V
f_NOM
f_LOW
f_HIGH
R_PLLIN
Nominal Frequency
Lowest Frequency
Highest Frequency
PLLIN Input Resistance
V_PLLFLTR = 1.2V
V_PLLFLTR = 0V
V_PLLFLTR ≥ 2.4V
360
400
440
kHz
230
260
290
kHz
480
550
590
kHz
50
kΩ
3729fb
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