PTB78560A_15 Datasheet, PDF (4/27 Pages) Texas Instruments – 30-W, 24-V/48-V INPUT DC/DC CONVERTERS WITH AUTO-TRACK™ SEQUENCING

PTB78560A, PTB78560B
PTB78560C
SLTS249 – JUNE 2005
www.ti.com
PTB78560B ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, T_A = 25°C, V_I = 24 V, V_O = 3.3 V, C_O = 330 µF, and I_O = I_Omax)
PARAMETER
TEST CONDITIONS
PTB78560B
MIN
TYP
MAX
I_O
Output current
Over V_I range
V_I
Input voltage range
Over I_O range
Set-point voltage tolerance
I_O Bus
I_O Seq
Sum total, (I_O Bus + I_O Seq)
0.25 ⁽¹⁾
0
0.25
18
24
±1 ⁽⁴⁾
8 ⁽²⁾
4 ⁽³⁾
8
60
Temperature variation
-40°C ≤ T_A ≤ 85°C
Line regulation
V_O
Load regulation
Over V_I range
Over I_O range
Total output voltage variation Includes set-point, line, load, –40°C ≤ T_A ≤ 85°C
Adjust range
Over V_I range
R_SET = 5.36 kΩ, V_O = 3.3 V
η
Efficiency
R_SET = 40.2 kΩ, V_O = 2.5 V
R_SET = open , V_O = 1.8 V
V_O Ripple (peak-to-peak)
20-MHz bandwidth
Transient response
0.1 A/µs load step,
50% to 100%
I_Omax , C_O = 330
µF
Recovery time
V_O over/undershoot
±0.5
±7
±33
±13
±33
±2
±3 ⁽⁴⁾
1.8
3.6
80%
77%
73%
50
100
±150
Input current
Track connected to -Sense
-0.13
Track input (pin 5)
Open-circuit voltage
Input slew rate limits
0
0.1 ⁽⁵⁾
V_O Bus
1
Referenced to -V_I
Output enable inputs (pins 2, 3)
Standby input current
Pins 2 and 3 open
Input high voltage (V_IH)
Input low voltage (V_IL)
Input low current (I_IL)
2
Open ⁽⁶⁾
-0.2
0.8
–0.8
8
16
I_O (tot) Overcurrent threshold
Shutdown, followed by autorecovery
12
UVLO Undervoltage lockout
V_I increasing
17
V_I decreasing
16
ƒ_S
Switching frequency
Over V_I range
400
500
600
Internal input capacitance
1
External input capacitance
External output capacitance
Isolation voltage
Between +V_I and –V_I
Between both outputs and V_O COM
Input-output
100
220
1,500
330 5,000
Isolation capacitance
Input-output
2,000
Isolation resistance
Input-output
10
MTBF Reliability
Telcordia SR-332 50% stress, T_A = 40°C, ground
benign
3.6
UNIT
A
V
%V_O
%V_O
mV
mV
%V_O
V
mV_pp
µs
mV
mA
V/ms
V
mA
mA
A
V
kHz
µF
µF
µF
Vdc
pF
MΩ
10⁶ Hr
(1) The converter requires a minimum load current at either the V_O Seq or V_O Bus output for proper operation. The converter is not
damaged when operated under a no-load condition.
(2) See temperature derating curves for safe operating area (SOA), to determine output current derating at elevated ambient temperatures.
(3) When load current is supplied from the V_O Seq output, the module exhibits higher power dissipation and slightly lower operating
efficiency.
(4) The set-point voltage tolerance is affected by the tolerance and stability of R_SET. The stated limit is unconditionally met if R_SET has a
tolerance of 1%, with 100 ppm/°C temperature stability.
(5) When controlling the Track input from an external source, the slew rate of the applied signal must be greater than the minimum limit.
Failure to allow the voltage to completely rise to the voltage at the V_O (bus) output, at no less than the minimum specified rate, may
thermally overstress the converter.
(6) The PEN and NEN inputs each have an internal pullup resistor. If the enable feature is not used, the PEN input (pin 2) should be left
open circuit and the NEN input (pin 3) permanently connected to –V_I. A discrete MOSFET or bipolar transistor is recommended for the
enable control. The open-circuit voltage is less than 10 V. See the Application Information for a more detailed description.
4
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