Datasheet

UC2827-1, UC2827-2
UC3827-1, UC3827-2
SLUS365D –APRIL 1999– REVISED APRIL 2011 www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise spsecified, V
VCC
= 15 V, V
V+
= 14.3 V, C
CT
= 340 pF, R
RT
= 10 kΩ, R
DELAY
= 24.3 kΩ, V
SRC
= V
GND
= V
BUCK
=
V
PUSH
= V
PULL
outputs no load, T
J
= T
A
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
CURRENT ERROR AMPLIFIER
IB –1 –5 µA
VIO 10 mV
AVOL 80 110 dB
GBW
(2)
Gain bandwidth At 100 kHz, Measure Gain 2 4.5 MHz
V
OL
I
CEAO
= 0 µA (No Load) 0.25 0.5 V
V
OH
I
CEAO
= 0 µA (No Load) 3.3 3.5 V
CMRR Common mode range
(2)
-0.3 5 V
OSCILLATOR SECTION
f
OSC
Frequency 180 220 250 kHz
I
CT(dsch)
CT discharge current 3.5V at CT when CT removed 5 mA
PWM COMPARATOR
D
MAX
Minimum duty cycle 200 kHz 0%
D
MAX
Maximum duty cycle 200 kHz 85% 91% 95%
BUCK OUTPUT STAGE
t
RISE
Rise time 1 nF Load
(3)
40 100 ns
t
FALL
Fall tIme 1 nF, Load 30 80 ns
I
BUCK
= –15 mA , V+ –BUCK
(4)
1.5 2.5 V
V
OH
High-level output voltage
IBUCK = –150 mA, V+ –BUCK
(4)
2 2.5 V
I
BUCK
= 15 mA
(5)
0.2 0.4 V
V
OL
Low-level output voltage
I
BUC
K = 150 mA
(5)
0.7 1.2 V
PUSH/PULL OUTPUT STAGES
t
RISE
Rise time 1 nF load 50 100 ns
t
FALL
Fall tIme 1 nF load 35 100 ns
Overlap time UCx827-1 1 nF loads
(6)
100 250 400 ns
Nonoverlapping time
(7)
UCx827-2 100 250 500 ns
I
PUSH/PULL
= –10 mA, VCC – PUSH
2 3 V
(8)
V
OH
High-level output voltage
I
PUSH/PULL
= –100 mA, VCC –
2.5 3 V
PUSH
(8)
I
PUSH/PULL
= 10 mA
(8)
0.2 0.8 V
V
OL
Low-level output voltage
I
PUSH/PULL
= 100 mA
(8)
0.6 1.2 V
REFERENCE
Reference voltage 4.8 5 5.2 V
I
SC
Shor-circuit current V
REF
= 0V –35 –50 –65 mA
Line regulation 0.5V < V
VCC
< 20 V 5 20 mV
Load regulation 0 mA < I
IO
< 10 mA 8 20 mV
SOFT START
V
OL
Low-level output voltage saturation V
VCC
= 7 V 250 500 mV
I
SS
Soft-start current –5 –12 –25 µA
(2) Ensured by design. Not production tested.
(3) Measure the rise time from when BUCK crosses 1 V until it crosses 9 V.
(4) To force BUCK high, force V
CSAO
=2.5 V, V
CEAO
= 2.5 V, a 25-kΩ pulldown resistor from RAMP to ground, and V
CT
= 0.5 V.
(5) To force BUCK low, force V
CSAO
= 2.5 V, V
CEAO
= 2.5 V, a 10-kΩ pulldown resistor from RAMP to ground, and V
CT
= 3.5 V.
(6) The overlap time is measured from the point at which the rising edge of PUSH/PULL crosses 5 V until the falling edge of PULL/PUSH
crosses 5V.
(7) The non-overlap time is measured from the point at which the falling edge of PUSH/PULL crosses 5 V until the rising edge of
PULL/PUSH crosses 5 V.
(8) To toggle PUSH or PULL into a desired state, pulse CT from 0.5 V to 3.5 V. PUSH and PULL toggle on the rising edge of CT.
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