Datasheet

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ELECTRICAL CHARACTERISTICS
PTN78020A
SLTS244A – APRIL 2005 – REVISED MAY 2005
operating at 25°C free-air temperature, V
I
= 20 V, V
O
= –5 V, I
O
= I
O
(max), C
I
= 100 µF and 4x 4.7 µF, C
O
= 100 µF (unless
otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
O
= -3 V 0.1 4
(1)
V
O
= -5 V 0.1 4
(1)
T
A
= 25 ° C, natural convec-
I
O
Output current A
tion airflow
V
O
= -12 V 0.1 2.1
(1)
V
O
= -15 V 0.1 1.67
(1)
V
O
= -3 V 9 29
(2)
V
O
= -5 V 9 27
(2)
V
I
Input voltage range Over I
O
range V
V
O
= -12 V 9 20
(2)
V
O
= -15 V 9 17
(2)
Set-point voltage tolerance T
A
= 25°C ±2%
(3)
Temperature variation -40°C to +85°C -0.5%
Line regulation Over V
I
range -10 mV
V
O
Load regulation Over I
O
range -10 mV
Includes set point, line, load
Total output voltage variation -3%
(3)
-40 < T
A
< 85°C
V
O
(adj) Output voltage adjust range 9 V ≤ V
I
≤ (32 – |V
O
|) V -15 - 3 V
V
I
= 12 V, R
SET
= 100 Ω, V
O
= –15 V 87%
V
I
= 12 V, R
SET
= 2 k Ω, V
O
= –12 V 86%
η Efficiency
V
I
= 20 V, R
SET
= 28.7 k Ω, V
O
= –5 V 82%
V
I
= 24 V, R
SET
= 221 k Ω, V
O
= –3.3 V 77%
Output voltage ripple 20-MHz bandwidth 1% V
O
V
(PP)
I
O (LIM)
Current limit threshold ∆ V
O
= –50 mV 8.5 A
1 A/µs load step from 50% to 100%
I
O
max
Transient response
Recovery time 200 µs
V
O
over/undershoot 5 %V
O
F
S
Switching frequency Over V
I
and I
O
ranges 440 550 660 kHz
UVLO Undervoltage lockout V
I
increasing 5.5 V
Ceramic 18.8
(4)
C
I
External input capacitance µF
Nonceramic 100
(4)
Ceramic 200
µF
C
O
External output capacitance Nonceramic 100
(5)
2,000
Equivalent series resistance (nonceramic) 10
(6)
m Ω
Per Telcordia SR-332, 50% stress,
MTBF Calculated reliability 5.6
10
6
Hrs
T
A
= 40°C, ground benign
(1) The maximum output current is 4 A, or a maximum output power of 25 W, whichever is less.
(2) The maximum input voltage is limited and defined to be (32 – |V
O
|) volts.
(3) 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 or better temperature stability.
(4) A minimum 100-µF electrolytic and four 4.7-µF ceramic capacitors are required across the input (V
I
and GND) for proper operation.
Locate the ceramic capacitors close to the module.
(5) 100 µF of output capacitance is required for proper operation. See the application information for further guidance.
(6) This is the typical ESR for all the electrolytic (nonceramic) capacitance. Use 17 m Ω as the minimum when using max-ESR values to
calculate.
3