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19-0923; Rev 0; 8/07
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
General Description
The MAX15009 includes a 300mA LDO regulator, a switched output, and an overvoltage protection (OVP) controller to protect downstream circuits from high-voltage load dump. The MAX15011 includes only the 300mA LDO regulator and switched output. Both devices operate over a wide supply voltage range from 5V to 40V and are able to withstand load-dump transients up to 45V. The MAX15009/MAX15011 feature short-circuit and thermalshutdown protection. These devices offer highly integrated power management solutions for automotive applications such as instrument clusters, climate control, and a variety of automotive power-supply circuits. The 300mA LDO regulator consumes 70A quiescent current at light loads and is well suited to power alwayson circuits during "key off" conditions. The LDO features independent enable and hold inputs, as well as a microprocessor (P) reset output with adjustable reset timeout period. The switched output of the MAX15009/MAX15011 incorporates a low RDS(ON) (0.28, typ) pass transistor switch internally connected to the output of the LDO regulator. This switch features accurate current-limit sensing circuitry and is capable of controlling remote loads. The MAX15009/MAX15011 feature an adjustable current limit and a programmable delay timer to set the overcurrent detection blanking time of the switch and autoretry timeout. The MAX15009 OVP controller operates with an external enhancement mode n-channel MOSFET. While the monitored voltage remains below the adjustable threshold, the MOSFET stays on. When the monitored voltage exceeds the OVP threshold, the OVP controller quickly turns off the external MOSFET. The OVP controller is configurable as a load-disconnect switch or a voltage limiter. The MAX15009/MAX15011 are available in a thermally enhanced, 32-pin (5mm x 5mm), TQFN package and are fully specified over the -40C to +125C automotive operating temperature range.
Features
300mA LDO Regulator, Switched Output, and OVP Controller (MAX15009) 300mA LDO Regulator and Switched Output (MAX15011) 5V to 40V Wide Operating Supply Voltage Range 45V Load Dump Protection 70A Quiescent Current LDO Regulator OVP Controller Disconnects or Limits Output Voltage During Battery Overvoltage Conditions LDO Regulator with Enable, Hold, and Reset Features Internal 0.28 (typ) n-Channel Switch for Switched Output 100mA Switched Output with Adjustable CurrentLimit Blanking/Autoretry Delay
MAX15009/MAX15011
Ordering Information
PART MAX15009ATJ+ MAX15011ATJ+* TEMP RANGE PINPACKAGE PKG CODE
-40C to +125C 32 TQFN-EP** T3255-4 -40C to +125C 32 TQFN-EP** T3255-4
+Denotes a lead-free package.
For tape and reel, add a T after "+." *Future product--contact factory for availability.
**EP = Exposed pad.
Pin Configurations
OC_DELAY OUT_LDO OUT_LDO EN_SW 17 16 15 14 13 EN_LDO FB_LDO N.C. SOURCE GATE N.C. FB_PROT CT 12 11 10 9 1 N.C. 2 N.C. 3 N.C. 4 N.C. 5 SGND 6 PGND 7 RESET 8 N.C.
TOP VIEW
ILIM
24 HOLD 25 N.C. 26 OUT_SW 27 OUT_SW 28 N.C. 29 N.C. 30 N.C. 31 N.C. 32
23
22
21
20
19
18
Applications
Instrument Clusters Climate Control AM/FM Radio Power Supply Multimedia Power Supply Telematics Power Supply
MAX15009
+
*EP
*EP = EXPOSED PAD
TQFN (5mm x 5mm)
Typical Operating Circuits and Selector Guide appear at end of data sheet.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
EN_PROT
IN
IN
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to SGND, unless otherwise noted.) IN, GATE.................................................................-0.3V to +45V EN_LDO, EN_SW, EN_PROT ......................-0.3V to (VIN + 0.3V) SOURCE ......................................................-0.3V to (VIN + 0.3V) OUT_LDO, FB_LDO, FB_PROT, RESET, OC_DELAY .........................................................-0.3V to +12V GATE to SOURCE ..................................................-0.3V to +12V OUT_SW, ILIM, HOLD ......................-0.3V to (VOUT_LDO + 0.3V) OUT_SW to OUT_LDO ...........................................-12V to +0.3V CT to SGND............................................................-0.3V to +12V SGND to PGND .....................................................-0.3V to +0.3V IN, OUT_LDO Current .......................................................700mA OUT_SW Current...............................................................350mA Current Sink/Source (all remaining pins) ............................50mA Continuous Power Dissipation (TA = +70C) 32-Pin TQFN (derate 34.5mW/C above +70C) .............2.7W* Thermal Resistance JA ..............................................................................29.0C/W JC ................................................................................1.7C/W Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature (soldering, 10s) .................................+300C *As per JEDEC 51 Standard, Multilayer Board (PCB).
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.
ELECTRICAL CHARACTERISTICS
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR < 1.5), COUT_LDO = 22F (ceramic), COUT_SW = 1F, VOUT_LDO = 5V, CT = open, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Supply Voltage Range SYMBOL VIN CONDITIONS VIN VOUT + 1.5V EN_LDO = IN, EN_SW = EN_PROT = 0V, IOUT_LDO = 0A, LDO on, switch off, protector off, measured from SGND EN_LDO = EN_SW = IN, EN_PROT = 0V, LDO ON, IOUT_LDO = 100A, switch on, IOUT_SW = 0A, protector off, measured from SGND EN_LDO = EN_SW = EN_PROT = IN, LDO ON, IOUT_LDO = 100A, switch on, IOUT_SW = 0A, protector on, measured from SGND EN_LDO = EN_SW = IN, LDO ON, IOUT_LDO = 100A, switch on, IOUT_SW = 0A, measured from SGND TA = -40C to +85C TA = -40C to +125C 4.10 4.27 260 MIN 5 TYP MAX 40 UNITS V
70
92
MAX15009 Supply Current IIN
290
360
A
360
500
MAX15011
220
340
Shutdown Supply Current
ISHDN
EN_LDO = EN_SW = EN_PROT = SGND, measured from SGND
16
30 A 40 4.45 V mV
IN Undervoltage Lockout IN Undervoltage Lockout Hysteresis
VUVLO VUVLO_HYST
VIN falling, GATE disabled
2
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Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR < 1.5), COUT_LDO = 22F (ceramic), COUT_SW = 1F, VOUT_LDO = 5V, CT = open, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Thermal-Shutdown Temperature Thermal Hysteresis LDO ILOAD = 1mA, FB_LDO = SGND Output Voltage VOUT_LDO ILOAD = 300mA, VIN = 8V, FB_LDO = SGND With respect to SGND, ILOAD = 1mA, VOUT_LDO = 5V, adjustable output option FB_LDO rising FB_LDO falling VFB_LDO = 1V Adjustable output option (Note 2) ILOAD = 300mA (Note 3) ILOAD = 200mA (Note 3) (Note 4) OUT_LDO = SGND, VIN = 6V 6V VIN 40V, ILOAD = 1mA, VOUT_LDO = 5V VOUT/ VIN 6V VIN 40V, ILOAD = 1mA, FB_LDO = SGND, VOUT_LDO = 3.3V 6V VIN 40V, ILOAD = 20mA, FB_LDO = SGND, VOUT_LDO = 5V 6V VIN 40V, ILOAD = 20mA, VOUT_LDO = 3.3V VOUT/ IOUT 1mA to 300mA, VIN = 8V, FB_LDO = SGND 1mA to 300mA, VIN = 6.3V, VOUT_LDO = 3.3V ILOAD = 10mA, f = 100Hz, 500mVP-P, VOUT_LDO = 5V 300 330 500 0.03 0.03 0.27 0.27 0.054 0.038 60 700 0.2 0.1 mV/V 1 0.5 0.15 mV/mA 0.100 dB -100 1.8 800 520 4.92 4.88 1.21 5.00 5.00 1.235 0.125 0.064 +100 11.0 1500 1000 5.09 5.11 1.26 V SYMBOL TSHDN THYST CONDITIONS MIN TYP +160 20 MAX UNITS C C
MAX15009/MAX15011
FB_LDO Set-Point Voltage Dual ModeTM FB_LDO Threshold FB_LDO Input Current LDO Output Voltage LDO Dropout Voltage LDO Output Current LDO Output Current Limit
VFB_LDO VFB_LDO_TH IFB_LDO VLDO_ADJ VDO IOUT_LDO ILIM_LDO
V V nA V mV mA mA
OUT_LDO Line Regulation
OUT_LDO Load Regulation
OUT_LDO Power-Supply Rejection Ratio OUT_LDO Startup Delay Time
PSRR
IOUT_LDO = 0mA, from EN_LDO rising to tSTARTUP_DELAY 10% of VOUT_LDO (nominal), FB_LDO = SGND
30
s
Dual Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR < 1.5), COUT_LDO = 22F (ceramic), COUT_SW = 1F, VOUT_LDO = 5V, CT = open, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER OUT_LDO Overvoltage Protection Threshold OUT_LDO Overvoltage Protection Sink Current ENABLE/HOLD INPUTS EN_LDO to EN_PROT Input Threshold Voltage EN_LDO, EN_PROT, EN_SW Input Pulldown Current HOLD Input Threshold Voltage HOLD Input Pullup RESET RESET goes HIGH when rising VOUT_LDO crosses this threshold, FB_LDO = SGND RESET goes HIGH when rising VFB_LDO crosses this threshold RESET goes LOW when falling VOUT_LDO crosses this threshold, FB_LDO = SGND RESET goes LOW when falling VFB_LDO crosses this threshold tRESET_FALL ICT VCT_TH VOL ILEAK_RESET VOUT_LDO falling, 0.1V/s VCT = 0V VCT rising ISINK = 1mA, output asserted Output not asserted 1.50 1.190 90.0 92.5 95.0 %VOUT_LDO VIH VIL IEN_PD VIH VIL IHOLD_PU HOLD is internally pulled high to OUT_LDO 0.6 EN_ is internally pulled low to SGND 1.4 0.4 1 2 0.7 V A V A SYMBOL VOV_TH IOV CONDITIONS 1mA sink from OUT_LDO VOUT_LDO = VOUT (nominal) x 1.15 8 MIN TYP 105 19 MAX 110 UNITS %VOUT_LDO mA
RESET Voltage Threshold HIGH
V R ESET_H
90.0
92.5
95.0
%VFB_LDO
RESET Voltage Threshold LOW
88
90
92
%VOUT_LDO
VRESET_L
88
90 19 2 1.235
92
%VFB_LDO s
VOUT_LDO to RESET Delay CT Ramp Current CT Ramp Threshold RESET Output-Voltage Low RESET Open-Drain Leakage Current
2.35 1.270 0.1 150
A V V nA
LOAD DUMP PROTECTOR (MAX15009 only) FB_PROT Threshold VTH_PROT Voltage FB_PROT Threshold Hysteresis FB_PROT Input Current Startup Response Time GATE Rise Time VHYST IFB_PROT tSTART tGATE
FB_PROT rising
1.20
1.235 4
1.27
V %VTH_PROT
VFB_PROT = 1.4V EN_PROT rising, EN_LDO = IN, to VGATE = 0.5V GATE rising to +8V, VSOURCE = 0V
-100 20 1
+100
nA s ms
4
_______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10F (ESR < 1.5), COUT_LDO = 22F (ceramic), COUT_SW = 1F, VOUT_LDO = 5V, CT = open, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER FB_PROT to GATE Turn-Off Propagation Delay SYMBOL tOV CONDITIONS FB_PROT rising from VTH_PROT 250mV to VTH_PROT + 250mV VSOURCE = VIN = 5.5V, RGATE to IN = 1M VSOURCE = VIN; VIN 14V, RGATE to IN = 1M VGATE = 5V, VEN_PROT = 0V GATE = SGND 12 VIN + 3.2 VIN + 7.0 VIN + 3.5 VIN + 8.1 63 45 16 18 MIN TYP MAX 0.6 VIN + 3.8 VIN + 9.5 100 UNITS s
MAX15009/MAX15011
GATE Output High Voltage
VGATE - VIN
V
GATE Output Pulldown Current GATE Charge-Pump Current GATE-to-SOURCE Clamp Voltage SWITCH Switch Dropout
IGATEPD IGATE VCLMP
mA A V
VSW
VSW = VOUT_LDO - VOUT_SW, IOUT_SW = 100mA, VOUT_LDO = 5V, no external MOSFET ILIM = OUT_LDO, VIN = 8V 170 85 30
36 200 100 40 0.395 1.194 1.235 16.0 1.00 12 38
70 240 120 50
mV
Switch Current Limit
ISW_LIM
RLIM = 100k to SGND, VOUT_LDO = 5V, VIN = 8V RLIM = 39k to SGND, VOUT_LDO = 5V, VIN = 8V
mA
Current-Limit Selector ILIM Voltage OC_DELAY Timeout Threshold OC_DELAY Timeout Pullup Current OC_DELAY Timeout Pulldown Current Minimum OC_DELAY Timeout EN_SW to OUT_SW Turn-On Time EN_SW to OUT_SW Turn-Off Propagation Delay
VILIM VOC_DELAY IOC_DELAY_UP IOC_DELAY_DOWN tOC_DELAY_MIN
RLIM = 100k
V 1.270 21.3 1.40 V A A s s
VOC_DELAY = 0.5V rising VOC_DELAY = 0.5V, falling COC_DELAY is unconnected OUT_SW rising to +0.5V, ROUT_SW = 1k
12.5 0.75
tOV_SW
EN_SW falling, VOUT_LDO - VOUT_SW rising to +1V, ROUT_SW = 1k, VOUT_LDO = 5V
18
s
Note 1: Note 2: Note 3: Note 4:
Specifications to -40C are guaranteed by design and not production tested. 1.8V is the minimum limit for proper HOLD functionality. Dropout is defined as VIN - VOUT_LDO when VOUT_LDO is 98% of the value of VOUT_LDO for VIN = VOUT_LDO + 1.5V. Maximum output current may be limited by the power dissipation of the package.
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5
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Typical Operating Characteristics
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10F, COUT_LDO = 22F, COUT_SW = 1F, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
LDO GROUND CURRENT vs. LOAD CURRENT
MAX15009 toc01
LDO GROUND CURRENT vs. LOAD CURRENT
130 LDO GROUND CURRENT (A) 120 110 100 90 TA = +85C 80 70 TA = +125C 10 5 TA = +25C TA = -40C ISHDN (A)
MAX15009 toc02
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
MAX15009 toc03
90 TA = -40C LDO GROUND CURRENT (A) 85 80 75 70 65 60 55 0 TA = +85C TA = +125C TA = +25C
140
35 30 25 20 15
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 LOAD CURRENT (mA)
60 0 25 50 75 100 125 150 175 200 225 250 275 300 LOAD CURRENT (mA)
0 -60 -40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (C)
LDO POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX15009 toc04
VIN UVLO HYSTERESIS vs. TEMPERATURE
MAX15009 toc05
LDO LOAD REGULATION
5.08 5.06 5.04
MAX15009 toc06
0 -10 -20 LDO PSRR (dB) -30 -40 -50 -60 -70
400 350 UVLO HYSTERESIS (mV) 300 250 200 150
5.10
VOUT_LDO (V)
5.02 5.00 4.98 4.96 4.94 4.92
-80 IOUT_LDO = 10mA -90 10 100 1k 10k 100k 1M 100 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
4.90 0 100 200 300 IOUT_LDO (mA)
FREQUENCY (Hz)
LDO OUTPUT VOLTAGE vs. INPUT VOLTAGE
IOUT_LDO = 10mA
MAX15009 toc07
LDO LOAD-TRANSIENT RESPONSE
MAX15009 toc08
LDO LOAD-TRANSIENT RESPONSE
MAX15009 toc09
6 5 4 3 2 1 0 0 5
VOUT_LDO (V)
IOUT_LDO = 300mA (PULSED)
IOUT_LDO 100mA/div 0A
IOUT_LDO 100mA/div
0A VOUT_LDO 5V, AC-COUPLED 20mV/div VOUT_LDO 5V, AC-COUPLED 100mV/div
10
15
20 VIN (V)
25
30
35
40
2ms/div
400s/div
6
_______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10F, COUT_LDO = 22F, COUT_SW = 1F, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
LDO OUTPUT VOLTAGE vs. TEMPERATURE
MAX15009 toc10
MAX15009/MAX15011
SWITCH LOAD-TRANSIENT RESPONSE
MAX15009 toc11
LINE-TRANSIENT RESPONSE
MAX15009 toc12
5.10 5.05 5.00 4.95 IOUT_LDO = 100mA 4.90 IOUT_LDO = 300mA 4.85 VIN = 8V 4.80 -50 -25 0 25 50 75 IOUT_LDO = 100A
VIN 20V/div IOUT_SW 100mA/div 0A VOUT_LDO 3.3V, AC-COUPLED 50mV/div VOUT_SW 3.3V, AC-COUPLED 50mV/div IOUT_LDO = 100mA IOUT_SW = 100mA 400s/div VOUT_PROT 20V/div 40ms/div 0V
IOUT_LDO = 10mA
VOUT_LDO (V)
VOUT_SW 5V, AC-COUPLED 100mV/div VOUT_LDO 5V, AC-COUPLED 100mV/div
0V
100 125 150
TEMPERATURE (C)
LINE-TRANSIENT RESPONSE
MAX15009 toc13
LDO DROPOUT VOLTAGE vs. LOAD CURRENT
MAX15009 toc14
SWITCH DROPOUT VOLTAGE vs. LOAD CURRENT
35 30 25 20 15 10 5 IOUT_LDO = 10mA 0
MAX15009 toc15
1000 900 LDO DROPOUT VOLTAGE (mV) 800 700 600 500 400 300 200 100 0V 0 0 100 200 0V
40 SWITCH DROPOUT VOLTAGE (mV)
VIN 10V/div VOUT_LDO 3.3V, AC-COUPLED 20mV/div VOUT_SW 3.3V, AC-COUPLED 20mV/div VOUT_PROT 10V/div 40ms/div
300
0
50 IOUT_SW (mA)
100
IOUT_LDO (mA)
SWITCH DROPOUT VOLTAGE vs. TEMPERATURE
IOUT_LDO = 10mA SWITCH DROPOUT VOLTAGE (mV) 50 40 30 20 IOUT_SW = 10mA 10 0 -45 -20 5 30 55 80 105 130 IOUT_SW = 100mA VRESET 5V/div VOUT_LDO 5V/div VOUT_SW 5V/div
MAX15009 toc16
STARTUP RESPONSE THROUGH VIN
MAX15009 toc17
60
VIN 20V/div 0V IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = EN_SW = IN 0V
0V
0V 20ms/div
TEMPERATURE (C)
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7
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10F, COUT_LDO = 22F, COUT_SW = 1F, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
STARTUP RESPONSE THROUGH EN
VIN VEN_LDO 5V/div IOUT_LDO = 100mA IOUT_SW = 70mA VEN_LDO = VEN_SW 0V
MAX15008 toc18
SHUTDOWN RESPONSE THROUGH VIN
MAX15008 toc19
SHUTDOWN RESPONSE THROUGH EN
VIN 20V/div VEN_LDO 5V/div VRESET 5V/div VOUT_LDO 5V/div VOUT_SW 5V/div IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = EN_SW 0V
MAX15008 toc20
14V VIN 10V/div IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = VEN_SW = IN
6V
0V
0V
0V
VRESET 5V/div VOUT_LDO 5V/div VOUT_SW 5V/div
VRESET 5V/div VOUT_LDO 5V/div VOUT_SW 5V/div 2ms/div
0V
0V
0V
0V
0V 20ms/div
0V
0V
LDO, EN_LDO, AND HOLD TIMING
MAX15009 toc21
GROUND CURRENT DISTRIBUTION HISTOGRAM (-40C)
MAX15009 toc22
GROUND CURRENT DISTRIBUTION HISTOGRAM (+125C)
MAX15009 toc23
70 60 0V NUMBER OF PARTS 50 40 30 20 10 0V 0 44 47 50 53 56 59 62 65 68 71 74 77 80 GROUND CURRENT (A)
70 60 NUMBER OF PARTS 50 40 30 20 10 0 44 47 50 53 56 59 62 65 68 71 74 77 80 GROUND CURRENT (A)
VEN_LDO 5V/div VOUT_LDO 5V/div
HOLD PULLED UP TO OUT_LDO
0V
HOLD 5V/div RESET 5V/div 200ms/div
0V
PROTECTOR GATE VOLTAGE vs. INPUT VOLTAGE (MAX15009 ONLY)
45 40 GATE VOLTAGE (V) 35 30 25 20 15 10 5 0 0 5 10 15 20 VIN (V) 25 30 35 40 VIN VOUT_PROT 10V/div VGATE 10V/div VGATE
MAX15009 toc24
PROTECTOR STARTUP RESPONSE
MAX15009 toc25
50
VIN 10V/div 0V
0V
0V IOUT_PROT = 1A 10ms/div
8
_______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10F, COUT_LDO = 22F, COUT_SW = 1F, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25C, unless otherwise specified.)
RESET TIMEOUT DELAY vs. CRESET
6 RESET TIMEOUT DELAY (ms) 0V 5 4 3 2 1 0V 40ms/div 0 0 2 4 6 8 10 CRESET (nF)
MAX15009 toc28
MAX15009/MAX15011
OVERVOLTAGE SWITCH FAULT
MAX15009 toc26
OVERVOLTAGE LIMIT FAULT
MAX15009 toc27
7
VIN 10V/div
VIN 20V/div IOUT_PROT = 1A VOV = 25V 0V VGATE 20V/div IOUT_PROT = 1A OV THRESHOLD = 35V VOUT_PROT 20V/div 0V 400s/div 0V
VGATE 20V/div 0V VOUT_PROT 20V/div
RESET TIMEOUT DELAY vs. TEMPERATURE
MAX15009 toc29
SWITCH CURRENT LIMIT vs. ILIM RESISTANCE
180 SWITCH CURRENT LIMIT (mA) 160 140 120 100 80 60 40 20 TA = +25C TA = -40C TA = +85C TA = +125C
MAX15009 toc30
2.0 1.8 RESET TIMEOUT DELAY (ms) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -50 -25 0 25 50 75 CRESET = 220pF CRESET = 2.2nF
200
100 125 150
20
40
60
80 100 120 140 160 180 200 ILIM RESISTANCE (k)
TEMPERATURE (C)
INTERNAL PRESET SWITCH CURRENT LIMIT vs. TEMPERATURE
OC_DELAY PULLUP/PULLDOWN CURRENT (A)
MAX15009 toc31
IOC_DELAY_UP AND IOC_DELAY_DOWN vs. TEMPERATURE
16 14 12 10 8 6 4 2 0 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (C) IOC_DELAY_UP
MAX15009 toc32
250 240 PRESET CURRENT LIMIT (mA) 230 220 210 200 190 180 170 160 150 -50 -25 0 25 50 75
18 IOC_DELAY_DOWN
100 125 150
TEMPERATURE (C)
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9
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Pin Description
PIN 1-4, 8, 11, 14, 26, 29-32 1-4, 8, 10-14, 18, 26, 29-32 5 NAME MAX15009 N.C. MAX15011 -- No Connection. Not internally connected. -- SGND N.C. SGND Signal Ground Ground. PGND is also the return path for the overvoltage protector pulldown current for the MAX15009. In this case, connect PGND to SGND at the negative terminal of the bypass capacitor connected to the source of the external MOSFET. For the MAX15011, connect PGND to SGND together to the local ground plane. Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for the duration of the reset timeout period then goes high. Reset Timeout Adjust Input. Connect a capacitor (CRESET) from CT to ground to adjust the reset timeout period. See the Setting the RESET Timeout Period section. Overvoltage-Threshold Adjustment Input. Connect FB_PROT to an external resistive voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to monitor a system input or output voltage. See the Setting the Overvoltage Threshold (MAX15009 Only) section. Protector Gate Drive Output. Connect GATE to the gate of an external n-channel MOSFET. GATE is the output of a charge pump with a 45A pullup current to 8.1V (typ) above IN during normal operation. GATE is quickly turned off through a 63mA internal pulldown during an overvoltage condition. GATE then remains low until FB_PROT has decreased below 96% of the overvoltage threshold. GATE pulls low when EN_PROT is low. Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel MOSFET. FUNCTION
6
PGND
PGND
7
RESET
RESET
9
CT
CT
10
FB_PROT
--
12
GATE
--
13
SOURCE
--
10
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Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Pin Description (continued)
PIN NAME MAX15009 FB_LDO MAX15011 FB_LDO FUNCTION LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable output operation. See the Setting the Output Voltage section. Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND through a 1A current sink. See the Control Logic section. Active-High Switch Enable Input. Connect EN_SW to IN or to a logic-high voltage to turn on the switch. Pull EN_SW low or leave unconnected to place the switch in shutdown. EN_SW is internally pulled to SGND through a 1A current sink. Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1A sink current. Connect EN_PROT to IN for normal operation. Regulator Input. Bypass IN to SGND with a 10F capacitor with an ESR < 1.5. LDO Regulator Output. Bypass OUT_LDO to SGND with a ceramic capacitor with a minimum value of 22F. OUT_LDO has a fixed 5V output or can be adjusted from1.8V to 11V. See the Setting the Output Voltage section. Switch Overcurrent Blanking Time Programming Input. Leave OC_DELAY unconnected to select the minimum delay timeout before turning the switch off. OC_DELAY is internally pulled to SGND through a 1A current source. See the Programming the Switch Overcurrent Blanking Time section. Switch Current-Limit Set Input. Connect a 10k to 200k resistor from ILIM to SGND to select the current limit for the internal switch. Connect ILIM to OUT_LDO to select the internal 170mA (min) current-limit threshold. Do not leave ILIM unconnected. See the Setting the Switch Current Limit section. Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator latches the state of the EN_LDO input and allows the regulator to remain turned on when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a 0.6A current source. See the Control Logic section. Switch Output. Bypass OUT_SW to SGND with a minimum 0.1F ceramic capacitor. Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize thermal dissipation. Do not use as the main ground connection.
MAX15009/MAX15011
15
16
EN_LDO
EN_LDO
17
EN_SW
EN_SW
18 19, 20 21, 22
EN_PROT IN OUT_LDO
-- IN OUT_LDO
23
OC_DELAY
OC_DELAY
24
ILIM
ILIM
25
HOLD
HOLD
27, 28 --
OUT_SW EP
OUT_SW EP
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11
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Functional Diagram
IN VIN IN LDO BIAS AND VOLTAGE REFERENCE VREF 1.235V
ENABLE LDO HOLD
EN_LDO HOLD CONTROL LOGIC OUT_LDO 5V LDO OUTPUT
M U X
FB_LDO
2A
0.124V CT
0.925 x VREF
VREF
RESET
RESET OUTPUT
OUT_LDO ILIM 16A OUT_SW SWITCH
VGATE
VREF S ENABLE SWITCH EN_SW Q 0.1V OC_DELAY R
OUT_SW
SWITCH OUTPUT
1A
IN GATE UVLO 4.75V VREF GATE VIN
ENABLE PROTECTOR
EN_PROT
SOURCE
PROTECTOR OUTPUT
OVERVOLTAGE PROTECTOR (MAX15009 ONLY) EP SGND PGND
FB_PROT
12
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Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Detailed Description
The MAX15009/MAX15011 integrate a 300mA LDO voltage regulator, a current-limited switched output, and an OVP controller (MAX15009 only). These devices operate over a wide supply voltage range from 5V to 40V and are able to withstand load-dump transients up to 45V. The MAX15009/MAX15011 feature a 300mA LDO regulator that consumes 70A of current under light-load conditions and feature a fixed 5V or an adjustable output voltage (1.8V to 11V). Connect FB_LDO to ground to select a fixed 5V output voltage or select the LDO output voltage by connecting an external resistive voltage-divider at FB_LDO. The regulator sources at least 300mA of current and includes a current limit of 330mA (min). Enable the LDO by pulling EN_LDO high. The switch features accurate current-limit sensing circuitry and is capable of controlling remote loads. Once enabled, an internal charge pump generates the overdrive voltage for an internal MOSFET. The switch then starts to conduct and OUT_SW is charged up to VOUT_LDO. The switch is enabled when the output voltage of the LDO is above the RESET threshold voltage (92.5% of the LDO nominal output value). An overcurrent condition exists when the current at OUT_SW, IOUT_SW, exceeds the 200mA (typ) internal factory-set current-limit threshold or the externally adjustable current-limit threshold. During a continuous overcurrent event, the capacitor connected at OC_DELAY, COC_DELAY, is charged up to a voltage of 1.235V with a current, IOC_DELAY_UP. When this voltage is reached, an overcurrent latch is set and the gate of the internal MOSFET is discharged, reducing IOUT_SW. COC_DELAY is then discharged through a pulldown current, IOC_DELAY_DOWN (IOC_DELAY_UP / 16) and the internal MOSFET remains off until COC_DELAY has been discharged to 0.1V. After this user-programmable turnoff delay, the switch turns back on. This charge/ discharge is repeated if the overcurrent condition persists. The switch returns to normal operation once the overcurrent condition has been removed. The OVP controller (MAX15009 only) relies on an external MOSFET with adequate voltage rating (VDSS) to protect downstream circuitry from overvoltage transients. The OVP controller drives the gate of the external n-channel MOSFET, and is configurable to operate as an overvoltage protection switch or as a closed-loop voltage limiter.
GATE Voltage (MAX15009 Only)
The MAX15009 uses a high-efficiency charge pump to generate the GATE voltage for the external n-channel MOSFET. Once the input voltage, VIN, exceeds the undervoltage lockout (UVLO) threshold, the internal charge pump fully enhances the external n-channel MOSFET. An overvoltage condition occurs when the voltage at FB_PROT goes above the threshold voltage, VTH_PROT. After VTH_PROT is exceeded, GATE is quickly pulled to PGND with a 63mA pulldown current. The MAX15009 includes an internal clamp from GATE to SOURCE that ensures that the voltage at GATE never exceeds one diode drop below SOURCE during gate discharge. The voltage clamp also prevents the GATEto-SOURCE voltage from exceeding the absolute maximum rating for the VGS of the external MOSFET in case the source terminal is accidentally shorted to 0V.
MAX15009/MAX15011
Overvoltage Monitoring (MAX15009 Only)
The OVP controller monitors the voltage at FB_PROT and controls an external n-channel MOSFET, isolating, or limiting the load during an overvoltage condition. Operation in OVP switch mode or limiter mode depends on the connection between FB_PROT and the external MOSFET.
Overvoltage Switch Mode When operating in OVP switch mode, the FB_PROT divider is connected to the drain of the external MOSFET. The feedback path consists of the voltage-divider tapped at FB_PROT, FB_PROT's internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 1). When the programmed overvoltage threshold is exceeded, the internal comparator quickly pulls GATE to ground and turns
VIN
IN
GATE
MAX15009
FB_PROT SOURCE
PROTECTOR OUTPUT
SGND
Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009)
______________________________________________________________________________________ 13
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
off the external MOSFET, disconnecting the power source from the load. In this configuration, the voltage at the source of the MOSFET is not monitored. When the voltage at FB_PROT decreases below the overvoltage threshold, the MAX15009 raises the voltage at GATE, reconnecting the load to the power source.
VIN
IN
GATE
Overvoltage-Limiter Mode (MAX15009 Only) When operating in overvoltage-limiter mode, the feedback path consists of SOURCE, FB_PROT's internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 2). This configuration results in the external MOSFET operating as a hysteretic voltage regulator. During normal operation, GATE is enhanced 8.1V above VIN. The external MOSFET source voltage is monitored through a resistive voltage-divider between SOURCE and FB_PROT. When VSOURCE exceeds the adjustable overvoltage threshold, an internal pulldown switch discharges the gate voltage and quickly turns the MOSFET off. Consequently, the source voltage begins to fall. The VSOURCE fall time is dependent on the MOSFET's gate charge, the internal charge-pump current, the output load, and any load capacitance at SOURCE. When the voltage at FB_PROT is below the overvoltage threshold by an amount equal to the hysteresis, the charge pump restarts and turns the MOSFET back on. In this way, the OVP controller attempts to regulate VSOURCE around the overvoltage threshold. SOURCE remains high during overvoltage transients and the MOSFET continues to conduct during an overvoltage event. The hysteresis of the FB_PROT comparator and the gate turn-on delay force the external MOSFET to operate in a switched on/off sequence during an overvoltage event. Exercise caution when operating the MAX15009 in voltage-limiting mode for long durations. Care must be taken against prolonged or repeated exposure to overvoltage events while delivering large amounts of load current as the power dissipation in the external MOSFET may be high under these conditions. To prevent damage to the MOSFET, implement proper heatsinking. The capacitor tied between SOURCE and ground may also be damaged if the ripple current rating for the capacitor is exceeded.
MAX15009
SOURCE
PROTECTOR OUTPUT
FB_PROT SGND
Figure 2. Overvoltage Limiter (MAX15009)
As the transient voltage decreases, the voltage at SOURCE falls. For fast-rising transients and very large MOSFETs, connect an additional capacitor from GATE to PGND. This capacitor acts as a voltage-divider working against the MOSFET's drain-to-gate capacitance. If using a very low gate charge MOSFET, additional capacitance from GATE to ground might be required to reduce the switching frequency.
Control Logic
The MAX15009/MAX15011 LDO features two logic inputs, EN_LDO and HOLD, making these devices suitable for automotive applications. For example, when the ignition key signal drives EN_LDO high, the regulator turns on and remains on even if EN_LDO goes low, as long as HOLD is forced low and stays low after initial regulator power-up. In this state, releasing HOLD turns the regulator output (OUT_LDO) off. This feature makes it possible to implement a self-holding circuit without external components. Forcing EN_LDO low and HOLD high (or unconnected) places the regulator into shutdown mode, reducing the supply current to less than 16A. Table 1 shows the state of OUT_LDO with respect to EN_LDO and HOLD. Leave HOLD unconnected or connect directly to OUT_LDO to allow the EN_LDO input to act as a standard on/off logic input for the regulator.
14
______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
H Table 1. EN_LDO/HOLD Truth/State Table
OPERATION STATE Initial State EN_LDO Low HOLD Don't care OUT_LDO OFF COMMENT EN_LDO is pulled to SGND through an internal pulldown. HOLD is unconnected and is internally pulled up to OUT_LDO. The regulator is disabled. EN_LDO is externally driven high turning regulator on. HOLD is pulled up to OUT_LDO. HOLD is externally pulled low while EN_LDO remains high (latches EN_LDO state). EN_LDO is driven low or left unconnected. HOLD remains externally pulled low keeping the regulator on. HOLD is driven high or left unconnected while EN_LDO is low. The regulator is turned off and EN_LDO/HOLD logic returns to the initial state.
MAX15009/MAX15011
Turn-On State Hold Setup State Hold State
High High Low
Don't care Low Low High or unconnected
ON ON ON
Off State
Low
OFF
Applications Information
Load Dump
Most automotive applications run off a multicell 12V lead-acid battery with a nominal voltage that swings between 9V and 16V, depending on load current, charging status, temperature, and battery age, etc. The battery voltage is distributed throughout the automobile and is locally regulated down to voltages required by the different system modules. Load dump occurs when the alternator is charging the battery and the battery becomes disconnected. Power in the alternator (behaving now essentially as an inductor) flows into the distributed power system and elevates the voltage seen at each module. The voltage spikes have rise times typically greater than 5ms and decay within several hundred milliseconds but can extend out to 1s or more depending on the characteristics of the charging system. These transients are capable of destroying semiconductors on the first fault event. The MAX15009/MAX15011 feature load-dump transient protection up to +45V.
VIN IN OUT_LDO
MAX15009 MAX15011
FB_LDO
R1
R2
SGND
Figure 3. Setting the LDO Output Voltage
VOUT_LDO = VFB_LDO x (R1 + R2) / R2 where VFB_LDO = 1.235V and R2 50k.
Setting the RESET Timeout Period
The reset timeout period is adjustable to accommodate a variety of applications. Set the reset timeout period by connecting a capacitor, C RESET , between CT and SGND. Use the following formula to select the reset timeout period, tRESET: tRESET = CRESET x VCT_TH / ICT where t RESET is in seconds and C RESET is in F. VCT_TH is the CT ramp threshold in volts and ICT is the CT ramp current in A, as described in the Electrical Characteristics table.
Setting the Output Voltage
The MAX15009/MAX15011 feature dual-mode operation: these devices operate in either a preset voltage mode or an adjustable mode. In preset voltage mode, internal feedback resistors set the linear regulator output voltage (VOUT_LDO) to 5V. To select the preset 5V output voltage, connect FB_LDO to SGND. To select an adjustable output voltage between 1.8V and 11V, use two external resistors connected as a voltage-divider to FB_LDO (Figure 3). Set the output voltage using the following equation:
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15
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Leave CT open to select a typical reset timeout of 19s. To maintain reset accuracy, use a low-leakage type of capacitor. DC load current at OUT_SW, IOUT_SW_NOM and select the COC_DELAY using the following relationship: COC_DELAY IOC_DELAY_UP x VOUT_LDO x COUT_SW VOC_DELAY x (ISW_LIM - IOUT_SW_NOM)
Setting the Switch Current Limit
The switch block features accurate current-limit sensing circuitry. A resistor connected from ILIM to SGND can be used to select the current-limit threshold using the following relationship: ISW_LIM (mA) = RILIM (k) x 1mA / k where 20k RILIM 200k. Connect ILIM to OUT_LDO to select the default current limit of 200mA (typ).
Programming the Switch Overcurrent Blanking Time
The switch provides an adjustable overcurrent blanking time to allow the safe charge of large capacitive loads. When an overcurrent event is detected, a delay period elapses before the condition is latched and the internal MOSFET is turned off. This period is the overcurrent delay, tOC_DELAY. Set the overcurrent delay using the following equation: tOC_DELAY = COC_DELAY x VOC_DELAY / IOC_DELAY_UP where tOC_DELAY is in seconds and COC_DELAY is in F. VOC_DELAY is the overcurrent delay timeout threshold voltage in volts and IOC_DELAY_UP is the overcurrent delay timeout pullup current in A as seen in the Electrical Characteristics table. Ensure that the switch is not disabled due to a large startup inrush current by selecting a large enough value for overcurrent blanking time. Assume that the current available for charging the total switch output capacitance, COUT_SW, is the difference between the current-limit threshold value, ISW_LIM, and the nominal
COC_DELAY also affects the length of time before the MAX15009/MAX15011 attempt to turn the switch back on. Set the autoretry delay using the following equation: tOC_RETRY = COC_DELAY x VOC_DELAY/IOC_DELAY_DOWN where tOC_RETRY is in seconds, COC_DELAY is in F, VOC_DELAY is in volts, and IOC_DELAY_DOWN is in A. COC_DELAY should be a low-leakage type of capacitor with a minimum value of 100pF.
Setting the Overvoltage Threshold (MAX15009 Only)
The MAX15009 provides an accurate means to set the overvoltage threshold for the OVP controller using FB_PROT. Use a resistive voltage-divider to set the desired overvoltage threshold (Figure 4). FB_PROT has a rising 1.235V threshold with a 4% falling hysteresis. Begin by selecting the total end-to-end resistance, RTOTAL = R3 + R4. Choose RTOTAL to yield a total current equivalent to a minimum of 100 x IFB_PROT (FB_PROT's input maximum bias current) at the desired overvoltage threshold. See the Electrical Characteristics table. For example: With an overvoltage threshold (VOV) set to 20V, RTOTAL < 20V / (100 x IFB_PROT), where IFB_PROT is FB_PROT's maximum 100nA bias current: RTOTAL < 2M
VIN R5
IN
GATE PROTECTOR OUTPUT SOURCE
VIN
IN
GATE PROTECTOR OUTPUT SOURCE R3
MAX15009
FB_PROT
MAX15009
R6 SGND SGND
FB_PROT R4
Figure 4. Setting the Overvoltage Threshold (MAX15009)
16 ______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Use the following formula to calculate R4: R4 = VTH_PROT x RTOTAL / VOV where VTH_PROT is the 1.235V FB_PROT rising threshold and VOV is the desired overvoltage threshold. R4 = 124k: RTOTAL = R3 + R4 where R3 = 1.88M. Use a standard 1.87M resistor. A lower value for total resistance dissipates more power, but provides better accuracy and robustness against external disturbances.
External MOSFET Selection
Select the external MOSFET with adequate voltage rating, VDSS, to withstand the maximum expected load-dump input voltage. The on-resistance of the MOSFET, RDS(ON), should be low enough to maintain a minimal voltage drop at full load, limiting the power dissipation of the MOSFET. During regular operation, the power dissipated by the MOSFET is: PNORMAL = ILOAD2 x RDS(ON) Normally, this power loss is small and is safely handled by the MOSFET. However, when operating the MAX15009 in overvoltage limiter mode under prolonged or frequent overvoltage events, select an external MOSFET with an appropriate power rating. During an overvoltage event, the power dissipation in the external MOSFET is proportional to both load current and to the drain-source voltage, resulting in high power dissipated in the MOSFET (Figure 6). The power dissipated across the MOSFET is: POV_LIMITER = VQ1 x ILOAD where VQ1 is the voltage across the MOSFET's drain and source during overvoltage limiter operation, and ILOAD is the load current.
VMAX
MAX15009/MAX15011
Input Transients Clamping
When the external MOSFET is turned off during an overvoltage event, stray inductance in the power path may cause additional input-voltage spikes that exceed the VDSS rating of the external MOSFET or the absolute maximum rating for the MAX15009. Minimize stray inductance in the power path using wide traces and minimize the loop area included by the power traces and the return ground path. For further protection, add a zener diode or transient voltage suppressor (TVS) rated below the absolute maximum rating limits (Figure 5).
VOV + VQ1 ILOAD IN GATE VSOURCE
VIN VSOURCE IN
MAX15009
TVS GATE
MAX15009
LOAD TVS SOURCE LOAD
SOURCE FB_PROT SGND SGND
Figure 5. Protecting the MAX15009 Input from High-Voltage Transients
Figure 6. Power Dissipated Across MOSFETs During an Overvoltage Fault (Overvoltage Limiter Mode)
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17
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Calculate the discharge time, t1, using the following equation: 0.04 x VOV t1 = CSOURCE x ILOAD + IGATEPD
t2
GATE
SOURCE
t1 tOVP
t3
where t 1 is in ms, V OV is the adjusted overvoltage threshold in volts, ILOAD is the external load current in mA, and IGATEPD is the 100mA (max) internal pulldown current of GATE. CSOURCE is the value of the capacitor connected between the source of the MOSFET and PGND in F.
Figure 7. MAX15009 Timing Diagram
Overvoltage-Limiter Mode Switching Frequency
When the MAX15009 is configured in overvoltagelimiter mode, the external n-channel MOSFET is subsequently switched on and off during an overvoltage event. The output voltage at OUT_PROT resembles a periodic sawtooth waveform. Calculate the period of the waveform, tOVP, by summing three time intervals (Figure 7): tOVP = t1 + t2 + t3 where t1 is the VSOURCE output discharge time, t2 is the GATE delay time, and t3 is the VSOURCE output charge time. During an overvoltage event, the power dissipated inside the MAX15009 is due to the gate pulldown current, I GATEPD . This amount of power dissipation is worse when ISOURCE = 0 (CSOURCE is discharged only by the internal current sink). The worst-case internal power dissipation contribution in overvoltage limiter mode, P OVP , in watts can be approximated using the following equation: t POVP = VOV x 0.98 x IGATEPD x 1 t OVP where VOV is the overvoltage threshold voltage in volts and IGATEPD is 100mA (max) GATE pulldown current.
GATE Delay Time (t2) When SOURCE falls 4% below the overvoltage-threshold voltage, the internal current sink is disabled and the internal charge pump begins recharging the external GATE voltage. Due to the external load, the SOURCE voltage continues to drop until the gate of the MOSFET is recharged. The time needed to recharge GATE and reenhance the external MOSFET is approximately:
t 2 = Ciss x VGS( TH) + VF IGATE
where t2 is in s, Ciss is the input capacitance of the MOSFET in pF, and VGS(TH) is the GATE-to-SOURCE threshold voltage of the MOSFET in volts. VF is the 0.7V (typ) internal clamp diode forward voltage of the MOSFET in volts, and IGATE is the charge-pump current 45A (typ). Any external capacitance between GATE and PGND adds up to Ciss. During t2, the SOURCE capacitance, CSOURCE, loses charge through the output load. The voltage across CSOURCE, V2, decreases until the MOSFET reaches its VGS(TH) threshold. Approximate V2 using the following formula: I xt V2 = LOAD 2 CSOURCE
Output Discharge Time (t1) When the voltage at SOURCE exceeds the adjusted overvoltage threshold, GATE's internal pulldown is enabled until VSOURCE drops by 4%. The internal current sink, I GATEPD , and the external load current, I LOAD , discharge the external capacitance from SOURCE to ground.
18
SOURCE Output Charge Time (t3) Once the GATE voltage exceeds the GATE-to-SOURCE threshold, VGS(TH), of the external MOSFET, the MOSFET turns on and the charge through the internal charge pump with respect to the drain potential, QG, determines the slope of the output voltage rise. The time required for the SOURCE voltage to rise again to the overvoltage threshold is:
t3 = Crss x VSOURCE IGATE
______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
where VSOURCE = (VOV x 0.04) + V2 in volts, and Crss is the MOSFET's reverse transfer capacitance in pF. Any external capacitance between GATE and PGND adds up to Crss. For prolonged exposure to overvoltage events, use the VIN voltage expected during overvoltage conditions. Under these circumstances the corresponding internal power dissipation contribution, POVP, calculated in the previous section should also be included in the total power dissipation, PDISS. For a given ambient temperature, T A, calculate the junction temperature, TJ, as follows: TJ = TA + PDISS x JA where TJ and TA are in C and JA is the junction-toambient thermal resistance in C/W as listed in the Absolute Maximum Ratings section. The junction temperature should never exceed +150C during normal operation.
MAX15009/MAX15011
Power Dissipation/Junction Temperature
During normal operation, the MAX15009/MAX15011 have two main sources of internal power dissipation: the LDO and the switched output. The internal power dissipation due to the LDO can be calculated as: PLDO = (VIN - VOUT_LDO ) x (IOUT_LDO + IOUT_SW ) where VIN is the LDO input supply voltage in volts, VOUT_LDO is the output voltage of the LDO in volts, I OUT_LDO is the LDO total load current in mA, and IOUT_SW is the switch load current in mA. Calculate the power dissipation due to the switch as: PSW = VSW x IOUT _ SW where VSW is the switch dropout voltage in volts for the given IOUT_SW current in mA. The total power dissipation PDISS in mW as: PDISS = PLDO + PSW
Thermal Protection
When the junction temperature exceeds TJ = +160C, the MAX15009/MAX15011 shut down to allow the device to cool. When the junction temperature drops to +140C, the thermal sensor turns all enabled blocks on again, resulting in a cycled output during continuous thermal-overload conditions. Thermal protection protects the MAX15009/MAX15011 from excessive power dissipation. For continuous operation, do not exceed the absolute maximum junction temperature rating of +150C.
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19
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Typical Operating Circuits
VOUT1 VOUT2
DC-DC MAX5073
CSOURCE GATE IN CIN SOURCE FB_PROT PGND SGND OUT_SW LDO ON/OFF SWITCH ON/OFF PROTECTOR ON/OFF HOLD EN_LDO SWITCH OUTPUT COUT_SW
5V TO 40V INPUT
MAX15009
EN_SW EN_PROT HOLD ILIM RESET RILIM CT CRESET OC_DELAY COC_DELAY OUT_LDO FB_LDO RPU 5V 300mA COUT_LDO C RESET/EN I/O VCC
5V TO 40V INPUT IN CIN OUT_SW COUT_SW 5V 300mA COUT_LDO FB_LDO RPU C RESET/EN I/O SWITCH OUTPUT
LDO ON/OFF SWITCH ON/OFF HOLD
EN_LDO EN_SW HOLD
MAX15011
OUT_LDO
VCC
RESET ILIM RILIM CT OC_DELAY CRESET COC_DELAY PGND SGND
20
______________________________________________________________________________________
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Pin Configurations (continued)
OC_DELAY
Selector Guide
PART LDO SWITCHED OUTPUT OVP CONTROLLER --
MAX15009/MAX15011
OUT_LDO
EN_SW
TOP VIEW
ILIM
OUT_LDO
N.C.
MAX15009 MAX15011
16 15 14 13 EN_LDO FB_LDO N.C. N.C. N.C. N.C. N.C. CT
IN 20
24 HOLD 25 N.C. 26 OUT_SW 27 OUT_SW 28 N.C. 29 N.C. 30 N.C. 31 N.C. 32 1 N.C.
23
22
21
19
IN
18
17
Chip Information
PROCESS: BiCMOS
MAX15011
12 11
+
2 N.C. 3 N.C. 4 N.C. 5 SGND 6 PGND
*EP
10 9
7 RESET
8 N.C.
TQFN (5mm x 5mm)
*EP = EXPOSED PAD
______________________________________________________________________________________
21
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
1
2
22
______________________________________________________________________________________
QFN THIN.EPS
Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX15009/MAX15011
PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
2
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23
(c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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