19-0603; Rev 0; 7/06
40V, 600mA Buck Converters with Low-
Quiescent-Current Linear Regulator Mode
General Description
The MAX5096/MAX5097 easy-to-use, Dual Mode™,
DC-DC converters operate as LDO (low dropout) or
switch-mode buck converters. At a high output load,
the converters operate as high-efficiency pulse-width-
modulated (PWM) switch-mode converters and reduce
the power dissipation. The devices switch to a low-qui-
escent-current (I
Q
) LDO mode of operation at light load.
During the key-off condition, the system’s microcon-
troller drives the LDO/BUCK input on the fly and forces
the MAX5096/MAX5097 into LDO Mode, thereby reduc-
ing the quiescent current significantly.
In Buck Mode, the MAX5096/MAX5097 operate from a 5V
to 40V input voltage range and deliver up to 600mA of
load current with excellent load and line regulation. The
fixed-switching frequency versions of 135kHz and
330kHz are available. The MAX5096/MAX5097 DC-DC
internal oscillator can be synchronized to an external
clock. External compensation and a current-mode control
scheme make it easy to design with.
In LDO Mode, the MAX5096/MAX5097 operate from a
4V to 40V input voltage. The LDO Mode operation is
intended for a lower output load current of up to
100mA. The quiescent current at 100µA load in LDO
Mode is only 41µA (typ).
The MAX5096/MAX5097 feature an enable input that
shuts down the device, reducing the current consump-
tion to 6µA (typ). Additional features include a power-on
reset output with a capacitor-adjustable timeout period,
programmable soft-start, output tracking, output over-
load, short-circuit and thermal shutdown protections.
The MAX5096/MAX5097 operate over the -40°C to
+125°C automotive temperature range and are avail-
able in thermally enhanced 20-pin TSSOP or 16-pin
TQFN packages.
Features
♦
High-Efficiency Switcher Mode (Buck Mode) or
Low-Quiescent-Current Linear Regulator
(LDO Mode) Operation
♦
Wide Operating Input Voltage Range
+5V to +40V Buck Mode
+4V to +40V LDO Mode
♦
Fixed 3.3V or 5V and Adjustable (1.24V to 11V)
Output Voltage Versions
♦
6µA (typ) Shutdown Current
♦
Fixed 135kHz or 330kHz Switching Frequency
♦
External Frequency Synchronization
♦
Programmable Soft-Start
♦
Integrated Microprocessor Reset (RESET) Circuit
with Programmable Timeout Period
♦
Thermal and Short-Circuit Protection
♦
-40°C to +125°C Automotive Temperature Range
♦
Thermally-Enhanced Package Dissipates
2.6W at T
A
= +70°C (16-Pin TQFN)
1.7W at T
A
= +70°C (20-Pin TSSOP)
MAX5096/MAX5097
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
PKG
CODE
T1655-2
T1655-2
U20E-4
U20E-4
T1655-2
T1655-2
U20E-4
U20E-4
MAX5096AATE+*
-40°C to +125°C 16 TQFN-EP**
MAX5096BATE+
-40°C to +125°C 16 TQFN-EP**
MAX5096AAUP+* -40°C to +125°C 20 TSSOP-EP**
MAX5096BAUP+* -40°C to +125°C 20 TSSOP-EP**
MAX5097AATE+
-40°C to +125°C 16 TQFN-EP**
MAX5097BATE+* -40°C to +125°C 16 TQFN-EP**
MAX5097AAUP+* -40°C to +125°C 20 TSSOP-EP**
MAX5097BAUP+* -40°C to +125°C 20 TSSOP-EP**
*Future
product—contact factory for availability.
+Denotes
lead-free package.
**EP
= Exposed pad.
Applications
LX
IN
IN
Pin Configurations
LX
TOP VIEW
TOP VIEW
Automotive
Industrial
+
PGND
SGND
RESET
BP
1
2
3
4
16
15
14
13
+
IN 1
12 EN
11 OUT
IN 2
IN 3
PGND 4
SGND 5
RESET 6
9
LDO/BUCK
BP 7
N.C. 8
SYNC 9
SS 10
20 LX
19 LX
18 N.C.
MAX5096
MAX5097
MAX5096
MAX5097
17 EN
16 OUT
15 ADJ
14 N.C.
13 LDO/BUCK
12 COMP
11 CT
10 ADJ
5
SYNC
6
SS
7
CT
8
COMP
Dual Mode is a trademark of Maxim Integrated Products, Inc.
TQFN
TSSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
40V, 600mA Buck Converters with Low-
Quiescent-Current Linear Regulator Mode
MAX5096/MAX5097
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to PGND, unless otherwise noted.)
IN (transient, 1ms) ..................................................-0.3V to +45V
SGND ....................................................................-0.3V to +0.3V
LX....................................................................-1V to (V
IN
+ 0.3V)
LX Current ................................................................................2A
EN ................................................................-0.3V to (V
IN
+ 0.3V)
BP, SYNC, LDO/BUCK,
RESET
to SGND...............-0.3V to +12V
BP,
RESET
Output Current..................................................25mA
CT, SS, ADJ, COMP to SGND ....................-0.3V to (V
BP
+ 0.3V)
OUT ........................................................................-0.3V to +11V
OUT Short-Circuit Duration ........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)*
16-Pin TQFN (derate 33.3mW/°C above +70°C) ........2666mW
20-Pin TSSOP (derate 21.7mW/°C above +70°C) ......1739mW
*As per JEDEC 51 Standard—Multilayer Board.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Thermal Resistance:
(θ
JA
, 16-Pin TQFN)* ...................................................30.0°C/W
(θ
JC
, 16-Pin TQFN).......................................................1.7°C/W
(θ
JA
, 20-Pin TSSOP)* .................................................46.0°C/W
(θ
JC
, 20-Pin TSSOP)........................................................2°C/W
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
IN
= +14V, I
OUT
= 1mA, C
IN
= 100µF, C
OUT
= 22µF, L = 22µH, C
BP
= 1µF, V
EN
= +2.4V (Figure 2), SGND = PGND = 0V, T
A
= T
J
=
-40°C to +125°C, unless otherwise noted. Typical values are at T
A
= T
J
= +25°C.) (Note 1)
PARAMETER
SYSTEM INPUT
Input Voltage Range (LDO Mode)
Input Voltage Range (Buck
Mode)
Internal Input Undervoltage
Lockout
Internal Input Undervoltage
Lockout Hysteresis
BP (Internal Regulator) Output
Voltage
V
IN_LDO
V
IN_BUCK
V
UVLO
LDO/BUCK = high
LDO/BUCK = low
V
BP
rising
4
5
3.5
3.65
0.185
3.75
4
4.20
40
40
3.9
V
V
V
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
UVLO_HYS
V
BP
falling
V
BP
V
IN
= +4.5V, I
BP
= 100µA
LDO/BUCK = high,
measured at input supply T
A
= -40°C to
+125°C
return, V
OUT
= 5V,
I
OUT
= 100µA
LDO/BUCK = high,
measured at input supply T
A
= -40°C to
return, V
OUT
= 5V,
+125°C
I
OUT
= 100mA
V
IN
= 14V, V
OUT
= 5V, I
OUT
= 0
T
A
= -40°C to
+125°C
T
A
= -40°C to
+85°C
I
Q
Quiescent Supply Current
(LDO Mode)
I
Q
41
70
µA
44
100
Buck Converter No-Load Supply
Current
I
Q_BUCK
680
6
6
19
µA
Shutdown Supply Current
I
SHDN
V
EN
= 0V, measured
from EN
µA
12
2
_______________________________________________________________________________________
40V, 600mA Buck Converters with Low-
Quiescent-Current Linear Regulator Mode
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +14V, I
OUT
= 1mA, C
IN
= 100µF, C
OUT
= 22µF, L = 22µH, C
BP
= 1µF, V
EN
= +2.4V (Figure 2), SGND = PGND = 0V, T
A
= T
J
=
-40°C to +125°C, unless otherwise noted. Typical values are at T
A
= T
J
= +25°C.) (Note 1)
PARAMETER
BUCK MODE
Supply Current
(Buck Converter On)
I
S
LDO/BUCK = low,
V
ADJ
= 1.4V, MAX5096,
no switching
LDO/BUCK = low,
V
ADJ
= 1.4V, MAX5097,
no switching
135kHz
version
693
980
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX5096/MAX5097
Supply Current
(Buck Converter On)
Fixed Output Voltage
ADJ Set Point
ADJ Input Bias Current
Dual Mode ADJ Threshold
Maximum Duty Cycle
Error Amplifier Transconductance
Adjustable Output Voltage Range
Minimum Output Current
Switch Current Limit
Internal Switch On-Resistance
Switch Leakage Current
Efficiency
Switching Frequency
Synchronization SYNC Input
SYNC Input High Threshold
SYNC Input Low Threshold
SYNC Input Minimum High Pulse
Width
SYNC Input Leakage
LDO MODE
Guaranteed Output Current
I
S
330kHz
Version
4.85
3.196
1.189
720
5
3.3
1.237
5
125
62
100
55
1.237
136
600
1.15
1.5
0.9
0.05
85
81
120
300
120
300
2.0
135
330
1000
5.12
3.391
1.280
100
µA
V
OUT
V
FB
I
FB
V
ADJTH_R
V
ADJTH_F
D
MAX
Gm
EA
V
ADJ
I
OUT
I
SW_LIM
R
DS(ON)
I
SW_L
η
f
SW
f
SYNC
V
SYNCH
V
SYNCL
5V version, 5.5V
≤
V
IN
≤
40V, no load
3.3V version, 5.5V
≤
V
IN
≤
40V, no load
50% duty cycle, no load
V
ADJ
= 1.5V
ADJ rising
ADJ falling
V
ADJ
= 0.5V
V
COMP
= V
ADJ
, I
COMP
= ±10µA
V
IN
= 6.5V to 40V
V
IN
= 6V to 40V
V
IN
= 14V, I
DRAIN
= 100mA
V
IN
= 40V, V
ADJ
= 1.5V
V
IN
= 14V, V
OUT
= 5V, I
OUT
= 400mA
V
IN
= 14V, V
OUT
= 3.3V, I
OUT
= 400mA
MAX5096
MAX5097
MAX5096
MAX5097
V
BP
= 4V
V
BP
= 4V
V
V
nA
mV
%
210
11.000
1.90
2.1
3
µS
V
mA
A
Ω
µA
%
148
350
500
500
0.8
kHz
kHz
kHz
kHz
V
V
ns
250
V
SYNC
=11V
I
OUT
(Note 2)
100
1
µA
mA
_______________________________________________________________________________________
3
40V, 600mA Buck Converters with Low-
Quiescent-Current Linear Regulator Mode
MAX5096/MAX5097
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +14V, I
OUT
= 1mA, C
IN
= 100µF, C
OUT
= 22µF, L = 22µH, C
BP
= 1µF, V
EN
= +2.4V (Figure 2), SGND = PGND = 0V, T
A
= T
J
=
-40°C to +125°C, unless otherwise noted. Typical values are at T
A
= T
J
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
5V version, MAX5096B/MAX5097B,
5.5V
≤
V
IN
≤
40V, I
OUT
= 10mA
3.3V version, MAX5096A/MAX5097A,
4V
≤
V
IN
≤
40V, I
OUT
= 10mA
I
OUT
= 10mA
V
ADJ
= 4V
I
OUT
= 10mA
I
OUT
= 100mA,
V
OUT
= 0.98 x V
OUT(NOMINAL)
(5V version
only), MAX5096B/MAX5097B
Rising edge of EN to
V
OUT
= 10% V
OUT(NOMINAL)
,
R
L
= 500Ω, V
ADJ
= SGND,
LDO/BUCK = 4V, C
SS
= 2nF
∆V
OUT
/
∆V
IN
5V version,
+5.5V
≤
V
IN
≤
+40V, I
OUT
= 100mA
3.3V version,
+4V
≤
V
IN
≤
+40V, I
OUT
= 100mA
5V version,
I
OUT
= 100µA to
100mA, V
IN
= +14V
3.3V version,
I
OUT
= 100µA to
100mA, V
IN
= +14V
T
J
= +25°C
T
J
= -40°C to +125°C
T
J
= +25°C
T
J
= -40°C to +125°C
1.237
MIN
4.89
3.219
1.21
TYP
5
3.3
1.2375
0.5
MAX
5.09
3.378
1.26
100
11.000
0.37
UNITS
V
V
V
nA
V
V
Output Voltage
V
OUT
ADJ Set Point
ADJ Input Bias Current
Adjustable Output Voltage Range
Dropout Voltage
V
ADJ
I
FB
V
ADJ
∆V
DO
Startup Response Time
300
µs
0.125
mV/V
0.093
0.242
0.242
0.164
0.164
60
150
2.0
0.8
330
500
0.374
1
mV/mA
0.237
1
dB
mA
V
V
µA
Clock
Periods
µs
1
32
100
Line Regulation
Load Regulation
∆V
OUT
/
∆I
OUT
Power-Supply Rejection Ratio
Short-Circuit Current
LDO/BUCK High Threshold
LDO/BUCK Low Threshold
LDO/BUCK Input Leakage
Transition Timing from LDO Mode
to Buck Mode
Transition Timing from Buck
Mode to LDO Mode
PSRR
I
SC
I
OUT
= 10mA, f = 100Hz, 500mV
P-P
,
V
OUT
= +5V, V
IN
= +14V
V
IN
= 6V
BUCK MODE (LDO MODE TRANSITION)
LDO/BUCK = 11V
Falling edge of LDO/BUCK to buck
converter on
Rising edge of LDO/BUCK to LDO
operation
I
SS
V
SS-REF
V
ENH
V
SS
= 0.1V
V
OUT
= V
OUT(NOMINAL)
- 20%
EN = high, regulator on
3
0.9
1.4
SOFT-START, ENABLE (EN) AND
RESET
Soft-Start Charge Current
Soft-Start Reference Voltage
EN High-Voltage Threshold
5
0.99
7
1.1
µA
V
V
4
_______________________________________________________________________________________
40V, 600mA Buck Converters with Low-
Quiescent-Current Linear Regulator Mode
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +14V, I
OUT
= 1mA, C
IN
= 100µF, C
OUT
= 22µF, L = 22µH, C
BP
= 1µF, V
EN
= +2.4V (Figure 2), SGND = PGND = 0V, T
A
= T
J
=
-40°C to +125°C, unless otherwise noted. Typical values are at T
A
= T
J
= +25°C.) (Note 1)
PARAMETER
EN Low-Voltage Threshold
EN Input Pulldown
RESET
Voltage Threshold High
RESET
Voltage Threshold Low
RESET
Output-Low Voltage
RESET
Output-High Leakage
Current
RESET
Output Minimum Timeout
Period
V
OUT
to
RESET
Delay
Delay Comparator Threshold
Delay Comparator Threshold
Hysteresis
CT Charge Current
CT Discharge Current
THERMAL SHUTDOWN
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
T
J(SHDN)
∆T
J(SHDN)
Temperature rising
+165
20
°C
°C
I
CH
I
DISCH
V
CT
= 1V
0.74
V
CT_TH
V
RESET_H
V
RESET_L
V
RL
I
RH
SYMBOL
V
ENL
Regulator off
V
EN
= 2V, LDO/BUCK = 4V
V
OUT
rising
V
OUT
falling
I
SINK
= 1mA
V
RESET
= 5V, V
ADJ
= 1.5V
C
CT
= 0
V
OUT
falling 10mV/µs, C
CT
= 0
V
CT
rising
1.18
25
6
1.2374
100
1
13.8
1.20
1.29
90
87
0.5
92
90
94
92
0.2
1
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
µA
% V
OUT
% V
OUT
V
µA
µs
µs
V
mV
µA
mA
MAX5096/MAX5097
Note 1:
Limits to -40°C are guaranteed by design.
Note 2:
The continuous maximum output current from LDO is limited by package power dissipation.
_______________________________________________________________________________________
5
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