www. belling .com . cn 1 adjustable overvoltage protector with high accuracy b l8598 description the BL8598 overvoltage protection devices feature a low 1 8 0 (typ) ron internal fet and safeguards 2.2v to 28v systems from power supply overvoltage. if the input voltage exceeds the overvoltage threshold, the internal fet is turned off to prevent the output load circuits from damage. the overv oltage protection threshold can be adjusted with optional external resistors to any voltage between 4v and 8v. with the ovlo input set below the external ovlo select voltage, the BL8598 automatically choose the internal 2.5% accurate trip thresholds. the internal overvoltage thresholds (ovlo) are preset to 6.7 5 v typical. the BL8598 includes an internal thermal shutdown circuit which can protect against overcurrent events. BL8598 is available in dfn2x2 - 8 l package . features ? overv oltage protection up to 28v ? 2.5% accurate 6.75v ovlo threshold ? adjustable overvoltage protection trip level ? integrated 1 8 0 n - channel mosfet switc h ? automatic overvoltage protection trip - level selectio n ? internal 15ms startup delay ? thermal shutdown protection ? available in dfn2x2 - 8 l package ? temperature range : - 4 0 ? c ~85 ? c applications ? cell phones ? mp3 and mp4 players ? pdas and palmtop devices typical application r1 and r2 are required only for adjustable ovlo; otherwise, connect ovlo to gnd. pin out dfn2x2 - 8 l *connect exposed pad to gnd. bl 8 598
www. b elling .com . cn 2 b l8598 absolute maximum rating parameter value max input voltage 30 v vout - 0.3v C vin + 0.3v ovlo - 0.3v C 6v continuous vin current 1a peak vin current (note 1) 5a continuous ovlo current 50ua max operating junction temperature(tj) 125 ? c ambient temperature(ta) - 40 ? c C 85 ? c thermal resistance : ja 76.5 c/w storage temperature(ts) - 40 ? c - 150 ? c lead temperature & time 260 ? c, 10s note 1 : limited by thermal shutdown. note 2 : exceed these limits to damage to the device. exposure to absolute maximum rating conditions may affect device reliability. electrical characteristics ( v in=5v, ta=25 ? c) symbol parameter conditions min typ max unit vin input voltage range 2.2 28 v i in input supply current vin < ovlo 65 ua i q standby current 25 ua v in_ovlo overvoltage trip level vin rising 6.75 v v in_ovlo _hys overvoltage hysteresis 0.8 % v ovlo_thresh ovlo set threshold 1.24 v v ovlo_select external ovlo select threshold 0.3 v v ovlo_hys external ovlo select hysteresis 20 mv r on switch on - resistan c e 180 250 clamp = 10ua 5. 3 v thermal shutdown 145 150 indbc debounce time time from 1.6v < vin < v in_ovlo to vout = 10% of vin 15 ms t on switch turn - on time 1.6v < vin < v in_ovlo , r load = 100 load = 100uf; vout from 10% to 90% of vin 0.5 ms t off switch turn - off time vin > v ovlo _thresh to vout = 80% of v in_ovlo ; r load = 1k
www. b elling .com . cn 3 b l8598 timing diagram function diagram pin description pin name description 1, 2 vin supply voltage. connect 10uf capacitor from vin to gnd. connect all the vin pins to - gether for proper operation. 3 ovlo external ovlo adjustment. connect ovlo to gnd when using the internal threshold. connect a resistor - divider to ovlo to set a different ovlo threshold; this external resi stor - divider is completely independent from the internal threshold. 4 , 5 i.c. internally connected. don t connect. leave i.c. unconnected. 6 gnd ground 7 , 8 vout output voltage. connect all the vout pins together for proper operation. ep exposed pad. connect exposed pad to ground. for enhanced thermal dissipation, con - nect ep to a copper area as large as possible. don t use ep as a sole ground connect. r e g u l a t o r s e l e c t i o n o s c c h a r g e p u m p c l k c l k t i m i n g ( 1 5 m s ) v i n v o u t o v l o 0 . 3 v b a n d g a p c u r r e n t b i a s s e l 1 . 2 4 v o v p o t p e n r e s e t
www. b elling .com . cn 4 b l8598 typical performance characteristics t a =25 c unless specified. p ower - up response overvoltage rework response 0 10 20 30 40 50 60 70 80 90 0 2 4 6 8 10 supply current(ua) vin(v) supply current vs. vin t= - 40 t=+25 t=+85 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 - 50 - 25 0 25 50 75 100 nromalized ron temperature( ) normalized ron vs. temperature 0.95 0.97 0.99 1.01 1.03 1.05 - 50 - 25 0 25 50 75 100 125 nromalized ovlo threshold temperature( ) normalized ovlo threshold vs. temperature 0.90 0.95 1.00 1.05 1.10 1.15 1.20 - 50 - 25 0 25 50 75 100 125 normalized debounce time temperature( ) normalized debounce time vs. temperature
www. b elling .com . cn 5 b l8598 detailed description BL8598 overvoltage protection devices feature a low 1 8 0 (typ) ron internal fet and safeguards 2.2v to 28v systems from power supply overvoltage. if the input voltage exceeds the overvoltage threshold, the internal fet is turned off to prevent the output load circuits from damage. the 15ms debounce time guarantees proper turn on of the internal fet during star t up. device operation on initial power up, if vin > v ovlo_thresh , vout is disconnected from vin. if vin < v ovlo_thresh , the internal charge pump is enabled, the device enters startup after a 15ms debounce delay. internal switch BL8598 incorporate an interna l fet with a 180 ron. the fet is internally driven by a charge pump that generates a necessary gate voltage above vin. the internal fet is capable of passing more than 5a inrush current. overvoltage lockout(ovlo) BL8598 has a 6.75v ovlo threshold. thermal shutdown protection BL8598 has a thermal shutdown circuitry to turn off the internal fet when the junction temperature exceeds . the fet will recover automatically when the junction temperature falls by . application information vin bypass capacitor a 10uf ceramic capacitor is typically recommended for cin. cin should be located as close to the device vin pin as practically possible . if the power source has significant inductance due to long lead length, take care to prevent overshoots due to the lc tank circuit and provide protection if necessary to prevent exceed - ing the +30v absolute maximum rating on vin. output capacitor a 10uf output capacitor is required at the output. external ovlo adjustment functionality if ovlo is connected to ground, the internal ovlo comparator uses the internally set ovlo value. if ovlo is connected to the external resistor divider, and v ovlo exceeds the ovlo select voltage, v ovlo_select , the internal ovlo comparator is programmed with two resistors, r1 and r2. a suggested value for r1 is for minimum current consumption . in the case of and since v in_ovlo , v ovlo_thresh , r2 can be app roximated by the following formula: this external resistor divider is completely independent from the internal resistor divider.
www. b elling .com . cn 6 b l8598 package outline package dfn2x2 - 8l devices per reel 3000pcs unit m m package specification
|
