LTC3851A_15 Datasheet, PDF (3/30 Pages) Linear Technology – Synchronous Step-Down Switching Regulator Controller

LTC3851A
Electrical Characteristics The l denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T_A = 25°C (Note 2). V_IN = 15V, V_RUN = 5V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loops
V_IN
Operating Input Voltage Range
V_FB
Regulated Feedback Voltage
I_FB
V_REFLNREG
V_LOADREG
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
g_m
g_m GBW
I_Q
UVLO
UVLO Hys
Transconductance Amplifier g_m
Transconductance Amp Gain Bandwidth
Input DC Supply Current
Normal Mode
Shutdown
Undervoltage Lockout on INTV_CC
UVLO Hysteresis
I_TH = 1.2V (Note 4) 0°C to 85°C
I_TH = 1.2V (Note 4) –40°C to 125°C
I_TH = 1.2V (Note 4) –40°C to 150°C
I_TH = 1.2V (Note 4) –55°C to 150°C
(Note 4)
V_IN = 6V to 38V (Note 4)
(Note 4) Measured in Servo Loop,
∆I_TH = 1.2V to 0.7V
(Note 4) Measured in Servo Loop,
∆I_TH = 1.2V to 0.7V (H-Grade, MP-Grade)
(Note 4) Measured in Servo Loop,
∆I_TH = 1.2V to 1.6V
(Note 4) Measured in Servo Loop,
∆I_TH = 1.2V to 1.6V (H-Grade, MP-Grade)
I_TH = 1.2V, Sink/Source = 5µA (Note 4)
I_TH = 1.2V (Note 8)
(Note 5)
V_RUN = 5V
V_RUN = 0V
V_INTVCC Ramping Down
l4
38
V
l 0.792 0.800 0.808
V
l 0.788
0.812
V
l 0.788
0.812
V
l 0.788
0.812
V
–10 –50
nA
0.002 0.02 %/V
l
0.01 0.1
%
l
0.2
%
l
–0.01 –0.1
%
l
–0.2
%
2
mmho
3
MHz
1.2
mA
25 50
µA
3.25
V
0.4
V
V_OVL
Feedback Overvoltage Lockout
V_FB with Respect to Set Regulated Voltage V_FB Ramping
Positive (OV)
7.5 10 12.5
%
I_SENSE
SENSE Pins Current
I_TK/SS
Soft-Start Charge Current
V_RUN
RUN Pin On—Threshold
V_RUNHYS RUN Pin On—Hysteresis
V_SENSE(MAX) Maximum Current Sense Threshold
TG R_UP
TG R_DOWN
BG R_UP
BG R_DOWN
TG t_r
TG t_f
BG tr
BG tf
TG/BG t_1D
TG Driver Pull-Up On-Resistance
TG Driver Pull-Down On-Resistance
BG Driver Pull-Up On-Resistance
BG Driver Pull-Down On-Resistance
TG Transition Time
Rise Time
Fall Time
BG Transition Time
Rise Time
Fall Time
Top Gate Off to Bottom Gate On Delay
Bottom Switch-On Delay Time
±1 ±2
µA
V_TK/SS = 0V
V_RUN Rising
0.6
1
2
µA
l 1.10 1.22 1.35
V
120
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = 0V
l 20
30 40
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = 0V (H-/MP-Grade)
l 15
45
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = Float
l 40
53 65
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = Float (H-/MP-Grade)
l 35
70
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = INTV_CC
l 65
80 95
mV
V_FB = 0.7V, V_SENSE = 3.3V, I_LIM = INTV_CC (H-/MP-Grade) l 60
100 mV
TG High
2.2
Ω
TG Low
1.2
Ω
BG High
2.1
Ω
BG Low
1.1
Ω
(Note 6)
C_LOAD = 3300pF
C_LOAD = 3300pF
(Note 6)
C_LOAD = 3300pF
C_LOAD = 3300pF
C_LOAD = 3300pF Each Driver
(Note 6)
25
ns
25
ns
25
ns
25
ns
30
ns
BG/TG t_2D Bottom Gate Off to Top Gate On Delay Top C_LOAD = 3300pF Each Driver
Switch-On Delay Time
(Note 6)
30
ns
t_ON(MIN) Minimum On-Time
(Note 7)
90
ns
3851afa
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