LTC3858_15 Datasheet, PDF (3/38 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

LTC3858
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T_A = 25°C (Note 2). V_IN = 12V, V_RUN1,2 = 5V, EXTV_CC = 0V unless
otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
V_LOADREG Output Voltage Load Regulation
g_m1,2
I_Q
Transconductance Amplifier g_m
Input DC Supply Current
Pulse Skip or Forced Continuous Mode
(One Channel On)
Pulse Skip or Forced Continuous Mode
(Both Channels On)
(Note4)
Measured in Servo Loop,
l
∆I_TH Voltage = 1.2V to 0.7V
(Note4)
Measured in Servo Loop,
l
∆I_TH Voltage = 1.2V to 2V
(Note 4) I_TH1,2 = 1.2V, Sink/Source = 5μA
(Note 5)
RUN1 = 5V and RUN2 = 0V, V_FB1 = 0.83V (No Load) or
RUN1 = 0V and RUN2 = 5V, V_FB2 = 0.83V (No Load)
RUN1,2 = 5V, V_FB1,2 = 0.83V (No Load)
0.01 0.1
–0.01 –0.1
2
1.3
2
Sleep Mode (One Channel On)
Sleep Mode (Both Channels On)
Shutdown
RUN1 = 5V and RUN2 = 0V, V_FB1 = 0.83V (No Load) or
RUN1 = 0V and RUN2 = 5V, V_FB2 = 0.83V (No Load)
RUN1,2 = 5V, V_FB1,2 = 0.83V (No Load)
RUN1,2 = 0V
170 250
300 450
8
20
UVLO
Undervoltage Lockout
INTV_CC Ramping Up
INTV_CC Ramping Down
l
4.0
4.2
l 3.6
3.8
4
V_OVL
I_SENSE+
I_SENSE–
Feedback Overvoltage Protection
SENSE⁺ Pin Current
SENSE^– Pin Current
Measured at V_FB1,2, Relative to Regulated V_FB1,2
Each Channel
Each Channel
V_OUT1,2 < INTV_CC – 0.5V
V_OUT1,2 > INTV_CC + 0.5V
7
10
13
±1
±1
550 950
DF_MAX
Maximum Duty Factor
In Dropout, FREQ = 0V
98
99.4
I_SS1,2
Soft-Start Charge Current
V_SS1,2 = 0V
0.7
1.0
1.4
V_RUN1,2 On RUN Pin On Threshold Voltage
V_RUN1, V_RUN2 Rising
l 1.23 1.28 1.33
V_RUN1,2 Hyst RUN Pin Hysteresis Voltage
50
V_SS1,2 LA SS Pin Latch-Off Arming Threshold Voltage V_SS1, V_SS2 Rising from 1V
1.9
2
2.1
V_SS1,2 LT SS Pin Latch-Off Threshold Voltage
V_SS1, V_SS2 Falling from 2V
1.3
1.5
1.7
I_DSC1,2 LT SS Discharge Current
Short-Circuit Condition V_FB1,2 = 0V,
V_SS1,2 = 5V
7
10
13
V_SENSE(MAX) Maximum Current Sense Threshold Voltage V_FB1,2 = 0.7V, V_SENSE1–,₂– = 3.3V, I_LIM = 0
l 22
30
36
V_FB1,2 = 0.7V, V_SENSE1–,₂– = 3.3V, I_LIM = FLOAT l 43
50
57
V_FB1,2 = 0.7V, V_SENSE1–,₂– = 3.3V, I_LIM = INTV_CC l 64
75
86
Gate Driver
TG1,2
Pull-Up On-Resistance
2.5
Pull-Down On-Resistance
1.5
BG1,2
Pull-Up On-Resistance
2.4
Pull-Down On-Resistance
1.1
TG Transistion Time:
(Note 6)
TG1,2 t_r
Rise Time
C_LOAD = 3300pF
25
TG1,2 t_f
Fall Time
C_LOAD = 3300pF
16
BG Transistion Time:
(Note 6)
BG1,2 t_r
Rise Time
C_LOAD = 3300pF
28
BG1,2 t_f
Fall Time
C_LOAD = 3300pF
13
TG/BG t_1D Top Gate Off to Bottom Gate On Delay
C_LOAD = 3300pF Each Driver
30
Synchronous Switch-On Delay Time
UNITS
%
%
mmho
mA
mA
μA
μA
μA
V
V
%
μA
μA
μA
%
μA
V
mV
V
V
μA
mV
mV
mV
Ω
Ω
Ω
Ω
ns
ns
ns
ns
ns
3858fc
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