LTC3808 Datasheet, PDF (3/28 Pages) Linear Technology – No RSENSE TM, Low EMI, Synchronous DC/DC Controller with Output Tracking

LTC3808
ELECTRICAL CHARACTERISTICS The ● indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 4.2V unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
Overvoltage Protect Hysteresis
20
Auxiliary Feedback Threshold
0.325
0.4
0.475
Top Gate (TG) Drive Rise Time
C_L = 3000pF
40
Top Gate (TG) Drive Fall Time
C_L = 3000pF
40
Bottom Gate (BG) Drive Rise Time
CL = 3000pF
50
Bottom Gate (BG) Drive Fall Time
CL = 3000pF
40
Maximum Current Sense Voltage (∆V_SENSE(MAX))
(SENSE⁺ – SW)
IPRG = Floating (Note 6)
IPRG = 0V (Note 6)
IPRG = V_IN (Note 6)
● 110
125
140
● 70
85
100
● 185
204
223
Soft-Start Time (Internal)
Time for V_FB to Ramp from 0.05V to 0.55V
0.5
0.74
0.9
Oscillator and Phase-Locked Loop
Oscillator Frequency
Phase-Locked Loop Lock Range
Unsynchronized (SYNC/MODE Not Clocked)
PLLLPF = Floating
PLLLPF = 0V
PLLLPF = V_IN
SYNC/MODE Clocked
Minimum Synchronizable Frequency
Maximum Synchronizible Frequency
480
550
600
260
300
340
650
750
825
200
250
750
1000
Phase Detector Output Current
Sinking
f_OSC > f_SYNC/MODE
–3
Sourcing
f_OSC < f_SYNC/MODE
3
Spread Spectrum Frequency Range
Minimum Switching Frequency
460
Maximum Switching Frequency
635
SYNC/MODE Pull-Down Current
SYNC/MODE = 2.2V
2.6
PGOOD Output
PGOOD Voltage Low
PGOOD Trip Level
I_PGOOD Sinking 1mA
V_FB with Respect to Set Output Voltage
V_FB < 0.6V, Ramping Positive
V_FB < 0.6V, Ramping Negative
V_FB > 0.6V, Ramping Negative
V_FB > 0.6V, Ramping Positive
50
–13
–10.0
–7
–16
–13.3
–10
7
10.0
13
10
13.3
16
UNITS
mV
V
ns
ns
ns
ns
mV
mV
mV
ms
kHz
kHz
kHz
kHz
kHz
µA
µA
kHz
kHz
µA
mV
%
%
%
%
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3808E is guaranteed to meet specified performance from
0°C to 70°C. Specifications over the –40°C to 85°C operating range are
assured by design characterization, and correlation with statistical process
controls.
Note 3: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formula:
T_J = T_A + (P_D • θ_JA °C/W)
Note 4: Dynamic supply current is higher due to gate charge being
delivered at the switching frequency.
Note 5: The LTC3808 is tested in a feedback loop that servos I_TH to a
specified voltage and measures the resultant V_FB voltage.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as shown in Figure 1.
3808f
3