LTC3856 Datasheet, PDF (3/40 Pages) Linear Technology – 2-Phase Synchronous Step-Down DC/DC Controller with Diffamp

LTC3856
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3856EFE#PBF
LTC3856EFE#TRPBF
LTC3856FE
38-Lead Plastic TSSOP
–40°C to 125°C
LTC3856IFE#PBF
LTC3856IFE#TRPBF
LTC3856FE
38-Lead Plastic TSSOP
–40°C to 125°C
LTC3856EUH#PBF
LTC3856EUH#TRPBF
3856
32-Lead (5mm × 5mm) Plastic QFN
–40°C to 125°C
LTC3856IUH#PBF
LTC3856IUH#TRPBF
3856
32-Lead (5mm × 5mm) Plastic QFN
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
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 = 15V, V_RUN = 5V, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Main Control Loops
V_IN
Input Voltage
V_OUT
Output Voltage
V_FB
Regulated Feedback Voltage
I_FB
V_REFLNREG
V_LOADREG
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
g_m
I_Q
DF_MAX
UVLO
UVLO Hyst
Transconductance Amplifier g_m
Input DC Supply Current
Normal Mode
Shutdown
Maximum Duty Factor
Undervoltage Lockout
UVLO Hysteresis
I_TH Voltage = 1.2V, E-Grade (Note 4)
I_TH Voltage = 1.2V, I-Grade (Note 4)
(Note 4)
V_IN = 4.5V to 38V (Note 4)
(Note 4)
Measured in Servo Loop, ∆I_TH Voltage = 1.2V to 0.7V
Measured in Servo Loop, ∆I_TH Voltage = 1.2V to 1.6V
I_TH = 1.2V, Sink/Source 5µA (Note 4)
(Note 5)
V_IN = 15V
V_RUN = 0V
In Dropout; f_OSC = 500kHz
V_INTVCC Ramping Down
4.5
38
V
0.6
5.0
V
l 0.5955 0.600 0.6045
V
l 0.593 0.600 0.607
V
–15 –50
nA
0.002 0.02 %/V
l
0.01 0.1
%
l
–0.01 –0.1
%
2.0
mmho
4.0
mA
40 70
µA
93
94
%
l 3.0 3.2 3.4
V
0.6
V
V_OVL
I_SENSE+
I_TEMP
I_TK/SS
V_RUN
V_RUNHYS
V_SENSE(MAX)
Feedback Overvoltage Lockout
SENSE⁺ Pins Bias Current
DCR Tempco Compensation Current
Soft-Start Charge Current
RUN Pin On Threshold
RUN Pin On Hysteresis
Maximum Current Sense Threshold
(E-Grade)
V_SENSE(MAX) Maximum Current Sense Threshold
(I-Grade)
Measured at V_FB
Each Channel, V_SENSE1,2 = 3.3V
V_ITEMP = 0.3V
V_TK/SS = 0V
V_RUN Rising
V_FB = 0.5V, V_SENSE1,2 = 3.3V
I_LIM = 0V
I_LIM = Float
I_LIM = INTV_CC
V_FB = 0.5V, V_SENSE1,2 = 3.3V
I_LIM = 0V
I_LIM = Float
I_LIM = INTV_CC
l 0.64 0.66 0.68
V
l
±1 ±2
µA
l9
10 11
µA
l 1.0 1.25 1.5
µA
l 1.1 1.22 1.35
V
80
mV
l 25
30 35
mV
l 45
50 55
mV
l 68
75 82
mV
l 23
30 37
mV
l 43
50 57
mV
l 66
75 84
mV
3856f