LTC2921_15 Datasheet, PDF (18/20 Pages) Linear Technology – Power Supply Tracker with Input Monitors

LTC2921/LTC2922 Series
APPLICATIO S I FOR ATIO
∆V_L0
=
–0.8A
• 150mΩ
•

10Ω
100Ω

=
–12mV
= –0.24%of 5V
∆V_L1 = –1.6A •150mΩ • ^{} ₁₁₀₀₀^{ΩΩ} = –24mV
= –0.73%of 3.3V
∆V_L2
=
–0.4A
• 150mΩ
•

10Ω
100Ω

=
–6mV
= –0.24%of 2.5V
Confirm that the currents through the remote sense
switches are less than the Absolute Maximum Ratings:
I_DS1
=
0.8A
•

150mΩ
100Ω

=
1.2mA
I_DS2
=
1.6A
•

150mΩ
100Ω

=
2.4mA
I_DS3
=
0.4A
•

150mΩ
100Ω

=
0.6mA
The pull-down transistor Q5 on the V1 pin is a circuit
breaker reset mechanism. Choose the transistor to pull
down V_V1 below the reset threshold under worst-case
conditions, and choose a gate-grounding resistor based
on speed and current considerations. The Vishay Siliconix
Si1012R and a 100k resistor proved sufficient for this
design. Finally, bypass the V_CC pin with a 10µF capacitor.
TYPICAL APPLICATIO S
V_OUT ^{3.3V± 10%}
V_FB
DC/DC
CONVERTER
V_OUT ^{2.5V ± 5%}
V_FB
DC/DC
CONVERTER
V_OUT
V_FB
1.8V ± 5%
DC/DC
CONVERTER
V_OUT ^{1.5V ± 5%}
V_FB
DC/DC
CONVERTER
V_OUT ^{1.2V ± 5%}
V_FB
DC/DC
CONVERTER
QRST
Si1012R
CBRST
R1
100k
CIRCUIT BREAKER
RESET CONTROL
Five-Supply Tracker and Monitor (3.3V, 2.5V, 1.8V, 1.5V, 1.2V)
R_X0
100Ω
R_SENSE
WSL1206
0.05Ω, 1%
C_D0
0.1µF
25V
Q0
Si2316DS
R_G0
10Ω
R_X1
100Ω
C_D1
0.1µF
25V
Q1
Si2316DS
R_G1
10Ω
R_X2
100Ω
R_X3
100Ω
C_D2
0.1µF
25V
C_D3
0.1µF
25V
Q2
Si2316DS
R_G2
10Ω
Q3
Si2316DS
R_G3
10Ω
R_X4
100Ω
R_B1
178k
1%
R_A1
49.9k
1%
R_B2
113k
1%
R_B3
86.6k
1%
R_A2
49.9k
1%
R_A3
49.9k
1%
R_B4
60.4k
1%
R_A4
49.9k
1%
C_BYP
10µF
25V
3
4
V1
V2
5 _V3
6 _V4
C_D4
0.1µF
25V
19
18
V_CC SENSE ₁₇
GATE
16
PG
LTC2922-3.3
1 _S0
13 _S1
11 _S2
9 _S3
7 _S4
GND
15
D0 ²⁰
D1 ¹⁴
D2 ¹²
D3 ¹⁰
D4 ⁸
TIMER
2 C_TIMER
0.22µF
10V
Q4
Si2316DS
R_G4
10Ω
C_GATE
0.47µF
25V
18
3.3V
LOAD
0.8A MAX
2.5V
LOAD
2.3A MAX
1.8V
LOAD
1.6A MAX
1.5V
LOAD
1.4A MAX
1.2V
LOAD
1.2A MAX
R2
4.7k
RESET
PG PIN AS RESET
WITH PULL-UP
TO 2.5V
2921/22 TA02
29212fa